eastern hemlocks in Great Smoky Mountains National Park
As
we all know, eastern (Tsuga canadensis)
and Carolina (T. caroliniana) hemlocks
have suffered huge losses due primarily to the introduced hemlock woolly
adelgid (Adelges tsugae – HWA). In New England, there has been more
than a 60% decrease in total hemlock basal area since 1997 and a virtual
absence of hemlock regeneration in HWA-infested areas. HWA continues to spread
– most recently into western Michigan and Nova Scotia (all information, unless
otherwise indicated, is from Kinahan et
al. 2020; full citation at end of this blog). [However, Morin and Liebhold
(2015) found that hemlock basal volume continued to increase for the first 20
years or so after invasion by the adelgid, due to ingrowth of immature
hemlocks. See “results” in Morin et al.,
full citation at the end of the blog.]
This
loss deprives us of a gorgeous tree … and unique habitats. Hemlock-dominated
forests were characterized by deep shade, acidic and slowly decomposing soil,
and a cool microclimate. They provided unique and critical habitat for many
terrestrial and aquatic species.
A
team of scientists based at the University of Rhode Island has carried out an
experiment comparing cuttings from eastern hemlocks apparently resistant to HWA
to susceptible ones. Matching sets of resistant and susceptible trees were
planted at eight sites in seven states – Ithaca and Bronx, NY; Boston; southern
CT; Lycoming County, PA; Thurmont, MD; southern WV; and Waynesville, NC. All plantings
were within or adjacent to forests containing HWA-infested hemlocks.
After
four years, 96% of the HWA-resistant hemlocks had survived, compared to 48% of
the control plants. The HWA-resistant plants were 32% taller, put out 18% more
lateral growth, had 20% longer drip lines, and were in 58% better condition.
HWA was found on trees at only three out of the eight plots. HWA density on
resistant eastern hemlocks was 35% lower than on HWA-susceptible hemlocks,
although this difference was not statistically significant.
Trees
in all eight plots were infested with elongate hemlock scale (Fiorinia externa – EHS), a second insect
damaging hemlocks in eastern North America. However, the HWA-resistant hemlocks
had EHS densities 60% lower than those of the controls.
Kinahan et al. note that identification and use of host tree populations’ potential for pest resistance has played a role in other programs managing non-native pests and pathogens, including Dutch elm disease and chestnut blight.
The
same scientists note that significant effort has been put into biocontrol or
insecticides for management of hemlock woolly adelgid, but without achieving the
desired improvement of forest health. Attempts to cross eastern hemlocks with
HWA-resistant hemlocks unfortunately produced no viable offspring. However,
Kinahan et al. were inspired to
explore possible genetic resistance within natural populations of eastern
hemlocks by the 1) evidence of resistance in Asian and western hemlocks; 2) the
different foliar terpene profiles in those species; and 3) the presence of
apparently healthy mature hemlock trees growing in proximity to heavily
infested trees.
They asked forest managers and other concerned groups to help locate stands with trees that were mature and apparently completely healthy, were located within HWA-devastated hemlock stands, and had not been chemically treated. They chose a small stand of eastern hemlocks growing within the Walpack Fish and Wildlife Management Area in northern New Jersey. This stand was called the “Bulletproof Stand”. They evaluated HWA resistance in five of these trees, then chose two for propagation and planting in the test.
New Jersey’s “bullet-proof stand” on the left photo by Richard Casagrande
The
trees were planted in September 2015. Due to funding gaps, they were not
revisited for four years. Thus, Kinahan et
al. re-evaluated the resistant and vulnerable trees in Autumn 2019 – with
the results I reported above.
Does this study
prove that clonal propagation of apparently resistant hemlocks is an effective
strategy to restore the species?
It
is not that simple.
The
difference in survival and condition was striking, but the authors note several
caveats:
1)
they had not recorded pre-experiment data on plant height or other variables,
so they cannot be certain that variation in initial plant height or dripline
did not contribute to current treatment-level differences in these variables.
2)
they cannot distinguish between the impacts of HWA and EHS on plant growth.
3)
since they could not monitor the planting sites for four years, they cannot
definitively link increased mortality of HWA-susceptible trees to higher pest
densities. However, the lower pest densities and higher survival of
HWA-resistant hemlocks are consistent with herbivore-driven tree mortality.
They
also cannot assess the impact of other environmental stressors (drought, cold,
etc.) on their results.
4)
The small number of trees planted at each site prevented detailed site-level
analyses.
The
scientists conclude that their work is most appropriately viewed as a ‘proof of
concept’ experiment highlighting the need
for future research exploring how HWA-resistant eastern hemlocks might best be
integrated into existing HWA management.
Unfortunately, the
Rhode Island researchers report they cannot persuade the US Forest Service to
support continuing this effort. Will these promising hints not result in
action?
Kinahan
et al. stress the importance of the
reduced pest densities (both HWA and EHS) on the putatively resistant hemlocks.
They think this might be a result of the higher terpene concentrations in the
twigs and needles. Finally, they note that lower densities of sap-feeding
herbivores may also indirectly provide protection against other consumers,
including gypsy moth (Lymantria dispar)
and hemlock looper (Lambdina fiscellaria).
SOURCE
Kinahan,
I.G., G. Grandstaff, A. Russell, C.M. Rigsby, R.A. Casagrande, and E. L.
Preisser. 2020. A four-year, seven-state reforestation trial with eastern hemlocks
(Tsuga canadensis) resistant to hemlock woolly adelgid (Adelges tsugae).
Forests 11: 312
Morin, R.S. and A.M. Liebhold. 2015. Invasions by two non-native insects alter regional forest species composition and successional trajectories. Forest Ecology and Management 341 (2015).
Posted by Faith Campbell
P.S. I have been working with colleagues to promote a more coordinated and well-funded program to combat non-native forest pests – including much greater reliance on identifying and breeding resistance to the pest. Visit here to see this effort.
We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.
The California Department of Food and Agriculture (CDFA) is seeking comments on the appropriate pest rating for Leptosillia pistaciae, a recently discovered fungus that causes pistachio canker.
The
Department’s draft pest ranking assigns the highest Economic Impact score –
three. It assigns a medium Environmental Impact – two. This is because the
pathogen can kill an important native shrub, with possible follow-on
consequences of reduced biodiversity, disrupted natural communities, or changed
ecosystem processes.
CDFA
states that there is no uncertainty in its evaluation, but I see, and describe
here, numerous questions about the possible true extent of the invasion and
possible host range.
Comments are due
on April 4, 2020.
The
pathogen was detected in June 2019, when a habitat manager from an ecological
reserve in San Diego County noticed multiple dead lemonade berry shrubs (Rhus integrifolia) in one of the parks.
This is the first known detection of Leptosillia
pistaciae in the United States and on this host. USDA APHIS has classified Leptosillia pistaciae as a federal quarantine
pest. Rhus and Pistacia are in the same family, Anacardiaceae (cashews and sumacs).
According
to the CDFA, Leptosillia pistaciae is
the only member of this fungal genus known to be associated with disease
symptoms on plants. Other species are endophytes or found in dead plant
tissues. [It is not at all unusual for fungal species to be endophytes on some
plant hosts but pathogenic on others. A California example is Gibberella
circinata (anamorph Fusarium circinatum), which causes
pitch canker on Monterey pine (Pinus
radiata) but is an endophyte on various grass species (Holcus lanatus and Festuca
arundinacea).]
(Reminder: this is the second new pest of native species detected in California state in 2019; I blogged about an ambrosia beetle in Napa County here. )
Rhus integrifolia (lemonade berry
or lemonade sumac) is native to California. It grows primarily in the south, along
the coast – from San Diego to San Luis Obispo. However, some populations are
also found in the San Francisco Bay area. This and other sumacs are also sold
in the nursery trade.
On
pistachio trees in Italy, symptoms are observed in the winter and late spring. During
the winter dormant season, trees had gum exudation and cracking and peeling of
bark on trunks and branches. On trunks and large branches, cankers appeared
first as light, dead circular areas in the bark; subsequently they became
darker and sunken. Under the bark, cankers were discolored with necrotic
tissues; in some cases, these extended to the vascular tissues and pith. During
the active growing season, the symptomatic plants also showed canopy decline.
Inflorescences and shoots, originating from infected branches or twigs, wilted
and died. When the trunk was girdled by a canker, a collapse of the entire tree
occurred.
range map for Rhus integrifolia
On
lemonade berry, large clumps of dead
adult shrubs were observed on the edge of hiking trails. Some shrubs that had completely
dead foliage were re-sprouting from their bases. Trunks of shrubs that were not
completely dead were copiously weeping sap and fluids and showed foliage
browning and die back with symptoms of stress.
It
is thought that spores could be spread by wind, rain splashing, and the
movement of dead or dying trees, greenwaste, and infected nursery stock. Contaminated
pruning tools might also transport the spores. The possibility of a latent
phase – or perhaps asymptomatic hosts – adds to the probability of
anthropomorphically assisted spread.
I question how much effort has been put into detection surveys, especially in natural systems with native Rhus species. California has three other native sumacs: R. ovata, R. aromatica, and Malosma laurina (CNPS; full citation at the end of the blog). In addition, there are numerous other species in the family, including poison oaks (Toxicodendron spp.) and the widespread invasive plant genus Schinus.
Furthermore, some plants in the family (other than pistachios) are grown for fruit or in ornamental horticulture, including two of the native sumacs and two non-native species, Rhus glabra and R. lanceolata, cashew, mango, and smoke trees (Cotinus spp.).
Yet
CDFA confidently states that there are only two hosts and that it has been
detected in only one population – that in San Diego. This is because CDFA
considers only official records identified by a taxonomic expert and supported
by voucher specimens.
CDFA
states that the pathogen is likely to survive in all parts of the state where
pistachios are grown – primarily in the Central Valley. California supplies 98%
of the pistachios grown in the United States; the remainder is raised in
Arizona and New Mexico. California production occurred on 178,000 acres in
2012. A map is included in a flyer on production available at the url listed at
the end of this blog.
In
discussing spread potential, no mention is made of possible human-assisted
spread.
The CDFA document includes instructions for submitting comments; the deadline is April 4.
Sources:
Rhus and related
species native to California: California Native Plant Society
We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.
prickly pear cacti in Big Bend National Park photo by Blake Trester, National Park Service
The cacti that are such important components of desert ecosystems across nearly 2 million square miles straddling the U.S.-Mexico border are under threat from non-native insects – as I have noted in earlier blogs. Of course, cacti are important in other ecoregions, too – I wrote recently about the columnar cacti in the dry forests of Puerto Rico.
Flat-padded prickly pear cacti of the genus Opuntia are threatened by the cactus moth, Cactoblastis cactorum.
In 1989, the cactus moth was found
in southern Florida, to which it had spread from the Caribbean islands (Simonson
2005). Recently, the moth was found to have spread west as far as the Galveston,
Texas, area and near I-10 in Columbus, Texas, about 75 miles west of central
Houston (Stephen Hight, pers. com.) Two
small outbreaks on islands off Mexico’s Caribbean coast have been eradicated.
In Florida, the cactus moth has
caused considerable harm to six native species of prickly pear, three of which
are listed by the state as threatened or endangered.
When the cactus moth reaches the
more arid regions of Texas, it is likely to spread throughout the desert
Southwest and into Mexico. In the American southwest, 31 Opuntia species are at risk; nine of them are endemic, one is endangered.
Mexico is the center of endemism for the Opuntia
genus. In Mexico, 54 Opuntia species
are at risk, 38 of which are endemic (Varone et al. 2019; full citation at end of this blog).
The
long-term effects of the cactus moth on these North American Opuntia are unknown because there may be
substantial variations in tolerance. The attacks observed in the Caribbean
islands have shown great variability in various cactus species’ vulnerability (Varone et al. 2019).
The Opuntia cacti
support a diversity of pollinators as well as deer, javalina (peccaries),
tortoises, and lizards. Prickly pears also shelter packrats and nesting birds (which
in turn are fed on by raptors, coyotes, and snakes), and plant seedlings. Their
roots hold highly erodible soils in place (Simonson 2005).
While scientists have been concerned about the possible impacts of the cactus moth since it was detected in Florida 30 years ago, a substantial response began only 15 years later. The U.S. Department of Agriculture began trying to slow the spread of the cactus moth in 2005 (Mengoni Goñalons et al. 2014), with a focus on surveys and monitoring, host (cactus) removal, and release of sterile males. This program was successful at slowing the moth’s spread and eradicating small outbreaks on offshore islands of Alabama, Mississippi, and Mexico.
Cactus moth damage to native cacti in Florida photo by Christine Miller, UF/IFAS
However,
the moth continued to spread west and the program never received an appropriation from Congress. The primary funding source was a US – Mexico
Bi-National Invasive Cactus Moth Abatement Program. Both countries contributed
funds to support the research and operational program to slow the spread in the
U.S. Funds were provided through USDA Animal and Plant Health and Inspection
Service (APHIS) and the Mexican Secretariat of Agriculture, Livestock, Rural
Development, Fisheries and Food (SEGARPA). Unfortunately,
funding was reduced by both entities and became inadequate to maintain the
Bi-National Program.
Therefore, in 2012, APHIS abandoned
its regional program and shifted the focus to biocontrol. This is now
considered the only viable control measure in the desert Southwest where vulnerable
cacti are numerous and grow close together. The biocontrol project has been funded
since 2012 through the Plant Pest and Disease Management and Disaster
Prevention program (which receives funding through the Farm Bill). It has
received a total of slightly more than $2
million over seven years. More than half the funds went to the quarantine
facility to support efforts to rear non-target hosts and verify the biocontrol
agent’s host specificity. About a quarter of the funds supported complementary
work of an Argentine team (both the cactus moth and the most promising
biocontrol agent are native to Argentina). Much smaller amounts have supported
U.S.-based scientists who have studied other aspects of the cactus moth’s
behavior and collected and identified the U.S. moths being tested for their
possible vulnerability to attack by a biocontrol wasp.
Here are
details of what these dedicated scientists achieved in just the past seven
years at the relatively low cost of roughly $2 million. Unfortunately, the project now faces a funding crisis and
we need to ensure they have the resources to finish their work.
Some
Specifics of the BioControl Program
After literature reviews, extensive collections,
and studies in the cactus moth’s native habitat in Argentina (Varone et al. 2015), a newly described wasp, Apanteles
opuntiarum (Mengoni Goñalons et al. 2014), has been determined to be host
specific on Argentine Cactoblastis species and the most promising
candidate for biocontrol. Wasps were collected in Argentina and sent to
establish a colony in a quarantine facility in Florida to enable host
specificity studies on North American Lepidoptera (Varone et al. 2015).
Quarantine
host specificity studies and development of rearing technology has not been straightforward. Initially, it was
difficult to achieve a balanced male/female ratio in the laboratory-bred generations;
this balance is required to maintain stable quarantine laboratory colonies for
host range testing. This difficulty was overcome. A second challenge was high
mortality of the cactus-feeding insects collected in the Southwest that were to
be test for vulnerability to the biocontrol wasp. These desert-dwellers don’t
do well in the humid, air-conditioned climate of the quarantine facility! For
these difficult-to-rear native insects, scientists developed a molecular
genetics method to detect whether eggs or larvae of the cactus moth parasitoid were
present inside test caterpillars after they were exposed to the wasps. For easy
to rear test insects, caterpillars are exposed to the wasps and reared to
adulthood. Host specificity tests have been conducted on at least five species
of native U.S. cactus-feeding caterpillars and 11 species of non-cactus-feeding
caterpillars (Srivastava
et al. 2019; Hight pers.comm.).
To
date there has been no instance of
parasitism by Apanteles opuntiarum on either lepidopteran non-target species or
non-cactus-feeding insects in the Florida quarantine or in field collections in
Argentina (Srivastava et al.
2019; Varone et al. 2015; Hight pers.comm.).
The scientists expected to complete host-specificity testing in the coming months, then submit a petition to APHIS requesting the release of the wasp as a biocontrol agent. Unfortunately, the project’s request for about $250,000 in the current year was not funded. This money would have funded completion of the host specificity testing, preparation of a petition to APHIS in support of release of the biocontrol agent into the environment, and preparation of the release plan.
Meanwhile,
what can we expect regarding the probable efficacy of the anticipated biocontrol
program?
Some
of the wasp’s behavioral traits are encouraging. The wasp is widely present in
the range of the cactus moth, and persisted in these areas over the years of
the study. The wasp can deposit multiple eggs with each “sting”. Multiple wasps
can oviposit into each cactus moth without detriment to the wasp offspring. Unmated wasp females
produce male offspring only, whereas mated females produce mixed offspring
genders. In the field, female wasps attack cactus moth larvae in a variety of
scenarios: they wait at plant access holes to sting larvae when they come
outside to defecate; they attack larvae when they are moving on the surface of
the pads; they can sting the youngest cactus moth larvae through the thin plant
wall of mined the pads; and they enter large access holes created by older
larvae and attack larger larvae. The wasps are attracted by the frass
(excrement) left on the outside of the cactus pads by cactus moth larvae (Varone
et al. 2020).
However, I wonder about the extent
to which the cactus moth is controlled by parasitoids in Argentina. Cactoblastis eggs are killed
primarily by being dislodged during weather events (rain and wind) and by
predation by ants. First instar larvae are killed primarily by the native Argentine
cactus plants’ own defenses – thick cuticles and release of sticky mucilage when
the young larvae chew holes into the pads where they enter and feed internally.
As larvae feed and develop inside the pads, the primary cause of mortality is
natural enemies.
Of
all the parasitoid species that attack C. cactorum, A. opuntiarum
is the most abundant and important. When the larvae reach their final state (6th
instars), they leave the pads and find pupation sites in plant litter near the
base of the plants. It is at this stage that the parasitism from A.
opuntiarum is detected in the younger larvae that were attacked while
feeding inside pads. As the moth larva begins to spin silk into which to
pupate, larvae of the wasp erupt through the skin of the caterpillar and pupate
within the silk spun by the moth. Predation by generalists (ants, spiders,
predatory beetles) accounted for high mortality of the unprotected last instar
and pupae (Varone et al. 2019).
Finally,
the cactus moth has three generations per year when feeding on O. stricta in the subtropical and tropical coastal areas of the Americas
and the Caribbean. In Argentina, on its native host, the moth completes
only two generations per year (Varone et
al. 2019).
How to
Get the Program Support Needed
Opuntia in Big Bend National Park Photo by Cookie Ballou, National Park Service
To date, no organized
constituency has advocated for protection of our cacti from non-native insect pests.
Perhaps now that the Cactoblastis
moth is in Texas, the threat it represents to our desert ecosystems will become
real to conservationists and they will join the struggle. The first step is to
resolve the funding crisis so that the agencies can complete testing of the biocontrol
agent and gain approval for its release. So now there is “something people can
do” – and I hope they will step forward.
I hope Americans are not actually indifferent
to the threat that many cacti in our deserts will be killed by non-native
insects. Many are key components of the ecosystems within premier National
Parks, and other protected areas. Cacti also are beautiful treasures in
botanical gardens. I hope conservationists will agree that these threats must
be countered, and will help to ensure
funding of the final stages of the biocontrol tests.
Sources
Mengoni Goñalons, C., L. Varone, G. Logarzo, M. Guala, M.
Rodriguero, S.D. Hight, and J.E. Carpenter. 2014. Geographical range & lab
studies on Apanteles opuntiarum (hymenoptera: braconiDae) in AR, a candidate
for BC of Cactoblastis cactorum (Lepidoptera: Pyralidae) in North America. Florida
Entomologist 97(4) December 2014
Srivastava, M., P. Srivastava, R. Karan, A. Jeyaprakash,
L. Whilby, E. Rohrig, A.C. Howe, S.D. Hight,
and L. Varone. 2019. Molecular detection method developed to track the
koinobiont larval parasitoid Apanteles opuntiarum (Hymenoptera: Braconidae) imported from Argentina to control Cactoblastis cactorum (Lepidoptera:
Pyralidae). Florida Entomologist 102(2): 329-335.
Varone, L., C.M. Goñalons, A.C. Faltlhauser, M.E. Guala,
D. Wolaver, M. Srivastava, and S.D. Hight. 2020. Effect of rearing Cactoblastis cactorum on an artificial
diet on the behavior of Apanteles
opuntiarum. Applied Entomology DOI: 10.1111/jen.12731.
Varone,
L., G. Logarzo, J.J. Martínez, F. Navarro, J.E. Carpenter, and S.D. Hight.
2015. Field host range of Apanteles
opuntiarum (Hymenoptera: Braconidae) in Argentina, a potential biocontrol
agent of Cactoblastis cactorum
(Lepidoptera: Pyralidae) in North America. Florida Entomologist — Volume 98,
No. 2 803
Varone, L., M.B. Aguirre, E. Lobos, D. Ruiz Pérez, S.D. Hight, F. Palottini, M. Guala, G.A. Logarzo. 2019. Causes of mortality at different stages of Cactoblastis cactorum in the native range. BioControl (2019) 64:249–261
Posted by Faith Campbell
We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.
As happens every year, the Administration has proposed a budget for funding government programs in the next Fiscal Year (FY) – which begins on October 1, 2020 (FY2021). This proposal is not the final word. Congress will pass appropriations bills that will specify actual funding levels. NOW is the time for you to tell senators and representatives in Congress how much money you think agencies need to count tree-killing pests next year.
Pest programs most affected:
Sudden oak death (SOD):
Combination of goldspotted oak borer, laurel wilt, and thousand cankers disease
For the USFS, the Administration proposes alarming cuts.
Forest and Rangeland Research Program
FY18 F719 FY20 FY21 proposed
297,000,000 300,000,000 305,000,000 249,330,000
[In FYs 18 – 20, Forest Inventory & Analysis received $77 million of this total; the proposal for FY21 is $78.5 million. Under this proposal, inventory would receive more than 30% of all research funding!]
The Administration proposes to cut USFS R&D
overall by 25%. Also, it calls for closing the Pacific Southwest Research Station
in California.
These proposed cuts would come on top of severe reductions
over the past decade. Although the appropriation does not provide specific
spending figures for invasive species, funding for research conducted by the seven
research stations on ten non-native pests decreased from $10 million in FY2010
to just $2.5 million in FY2020 – a cut of more than 70%. The Service’s ability
to develop effective tools to manage the growing number of pests threatening
the health of the Nation’s forests is already crippled by the earlier cuts.
The proposal to close the Pacific Southwest Research Station is particularly unwise. This Station provides USFS’s crucially important expertise on both sudden oak death (SOD) and threats to Hawaiian forests, including rapid ʻōhiʻa death (ROD). These pathogens are already causing widespread and severe damage to forests in the region and leading experts work here.
USFS R&D must address two new threats associated
with sudden oak death:
need to better understand the possible impacts of the second, apparently more aggressive, genetic strain of the SOD pathogen now present in Oregon’s forests.
studies to determine which of the newly detected Phytophthora species found in Southeast Asia Link to blog and other regions might cause significant damage to America’s trees.
Other programs that USFS R&D should continue or
expand:
study the possible threat posed by the ambrosia beetle recently detected in Napa Valley of California.
understand the epidemiology and probable impacts of the recently detected beech leaf disease present from Ohio to Connecticut and possibly more widespread.
Forest Health Management Programs
Recent funding levels:
FY18 F719 FY20 FY21 proposed
96,500,000 98,000,000 100,000,000 73,636,000
The Forest Health Management (FHP)
Program supports federal agencies’ and partners’ efforts to prevent,
monitor, suppress, and eradicate insects,
diseases, and invasive plants. The White House proposes a $23 million cut, including a cut of $10
million to programs working on “cooperative lands” – all areas other than
federal lands. This proposed cut is short-sighted and worrisome. First, these forests
support a wide range of forest values. Second, non-native pests usually are usually
first introduced
in cities or suburbs – because they accompany imports destined for population centers. These newly arrived pests initially cause
enormous damage to urban forests. Counter-measures need to be initiated where
and when the pests arrive and their populations are low. We cannot afford to
wait for them to spread to national forest lands, when management will be
harder and more expensive.
Despite ever-rising numbers of non-native forest pests
over the past decade, funding for FHP work on Cooperative Lands has fallen by about
50%. Pest species suffering the largest cuts in recent FHP budgets are the
combination of gold spotted oak borer, thousand cankers disease, and laurel
wilt; Port-Orford cedar root disease, and threats to whitebark pines.
As I reported in a previous blog, an estimated 41% of forest biomass in the “lower 48” states is at risk from the 15 non-native pest species causing the greatest damage. Nevertheless, the Administration proposes to eliminate programs for several of the most hard-hit host tree species (redbay/laurel wilt, Port-Orford cedar, and whitebark pine) in FY2021. This proposal is contrary to priorities recommended through the CAPTURE project, which called for enhanced conservation efforts targetting these species specifically.
Also alarming is the cut to the informal “emerging pest” account. This valuable program funds projects targetting newly detected threats. Thus, in FY2019, FHP provided $125,000 to evaluate the probable impact of laurel wilt disease on sassafras, an important understory tree that grows throughout most of the Eastern Deciduous Forest. The program provided another $116,000 to support efforts to detect and understand beech leaf disease. Already, cuts in the overall FHP budget have necessitated cutting this valuable account from $1 million in FY19 to $750,000 in FY20 – and will probably result in additional cuts in FY21.
The budget proposes to cut funding to counter sudden oak death (SOD) Link to DMF by 15% — on top of a 52% cut since FY2018. SOD has killed an estimated 50 million trees from southern Oregon to central California. Not only does the pathogen continue to spread. Establishment of a second, more aggressive, genetic strain of the pathogen in the Oregon forest threatens to exacerbate the pathogen’s impact.
The forests of Hawai`i are facing their gravest threat
ever from a growing number of pests. FHP supported detection/monitoring of the
thrips attacking a dry forest tree, naio. There is a continuing need to address
threats to Hawaii’s most widespread tree, ʻōhiʻa lehua – which makes up 80%
of native forests – from the introduced “rapid ʻōhiʻa death”
fungi.
Finally, stakeholders will depend on leadership by the FHP program to manage spread of the emerald ash borer if the USDA Animal and Plant Health Inspection Service acts as expected and terminates the program under which it regulates movement of firewood, nursery stock, and other items that spread this pest. California and Oregon and other Western states are at greatest risk.
What You Can Do
Senators and representatives serving on the two
Interior Appropriations subcommittees will determine the final funding for USFS
programs.
Please ask them to support $303 million for USFS Research
and Development. Since the budget does not specify funding levels to be
allocated to non-native insects, pathogens, or other invasive species, ask for
“report language” instructing USFS to increase the funding for this vital
research area to five percent of the total research budget. Ask them also to
support maintaining the Pacific Southwest Research Station.
Also, ask them to support maintaining USFS Forest
Health and Management Programs at the FY20 level of $100 million in FY21. Ask
them to support $44 million for the “cooperative lands” program.
Members of the House Interior
Appropriations subcommittee
Betty
McCollum, Chair MN
Chellie Pingree ME
Derek Kilmer WA
José Serrano NY
Mike Quigley IL
Bonnie Watson Coleman NJ
Brenda Lawrence MI
David Joyce, Ranking Member OH
Mike Simpson ID
Chris Stewart UT
Mark Amodei NV
Members
of the Senate Interior Appropriations subcommittee
USDA Animal and Plant Health Inspection Service (APHIS)
Again, while the tree-killing pests
are usually introduced first in
cities or suburbs, the pests
don’t stay there. Instead, they proliferate and
spread … eventually threatening
forests across the continent.
APHIS has legal responsibility for preventing such pests’ entry, detecting newly introduced pests, and initiating eradication and containment programs intended to minimize the damage they cause. The risk of new introductions is tied to international trade. In 2017, an estimated 17,650 shipping containers (or 48 per day) infested by wood-boring insects entered the United States. Examples of such introductions include the Asian longhorned beetle, emerald ash borer, and several ambrosia beetles which carry the fungi now killing redbay and sassafras in the East, and sycamore and willow trees southern California. Other pests, such as gypsy moths and spotted lanternflies, are transported here as egg masses attached to hard-sided imports, containers, or ship superstructures. Yet more forest pests are brought here with or in imported plants. Two rapid ʻōhiʻa death (ROD) pathogens and beech leaf disease are among newly detected pests probably introduced this way.
APHIS
needs to be able to respond to these pests and to the others that will be
introduced in coming years. To do so, APHIS must have adequate funding for four
programs: “tree and wood pests” program at $60 million; “specialty crops”
program at $192 millon; “methods
development” at $28 million; and “detection” at $21 million.
The
“Tree and Wood Pests” account currently
supports
eradication and control efforts targeting only three insects: the
Asian longhorned beetle (ALB), emerald ash borer (EAB),
and gypsy moth. The program to eradicate the ALB has received about two-thirds of the funds — $40 million. It has succeeded
in eradicating 85% of the infestation in New York and some
of the outlying infestations in Ohio. There is
encouraging progress in Massachusetts, although at least one infested tree was
detected recently in a new town within the quarantine zone. Clearly, this
program must be maintained until final success is achieved everywhere.
The EAB program
has been funded at $7 million in recent years. APHIS has proposed to
terminate the EAB regulatory program. Program termination would greatly increase the risk that the EAB will
spread to the mountain and Pacific coast states, where both riparian woodlands
and urban forests would be severely damaged. Many stakeholders have urged APHIS
to continue
to regulate movement of firewood and other materials that facilitate the EAB’s spread.
The “Specialty Crops” program funds for APHIS’
regulation of nursery operations to prevent spread of the sudden
oak death pathogen. Were SOD to become established in the East,
it would threaten several oak species, sugar
maple, and black walnut. It is therefore alarming that in 2019, plants infected by the SOD
pathogen were shipped to 18 states. link to blog
APHIS must step up its regulatory efforts to prevent a repetition of this
disaster.
What You Can Do
Members of the Senate and House Agriculture
Appropriations Subcommittees will set final
funding levels for APHIS programs. Ask your members of Congressto support
maintaining the FY2020 funding levels for four APHIS programs: Tree
and Wood Pests, Specialty Crops, Methods Development, and “Detection
Funding”.
Also, ask them
to adopt report language urging APHIS to continue
regulating the EAB’s spread.
Members of
the House Agriculture Appropriations subcommittee
Sanford Bishop Jr., Chairman GA
Rosa DeLauro CT
Chellie Pingree ME
Mark Pocan WI
Barbara Lee Calif
13th (Oakland)
Betty McCollum MN
Henry Cuellar TX
Jeff Fortenberry, Ranking Member NE
Robert Aderholt AL
Andy Harris MD
John Moolenaar MI
Members of
the Senate Agriculture Appropriations subcommittee
We
welcome comments that supplement or correct factual information, suggest new
approaches, or promote thoughtful consideration. We post comments that disagree
with us — but not those we judge to be not civil or inflammatory.
This month is the 14th anniversary of United States’ implementation of International Standard for Phytosanitary Measure (ISPM) #15 with the goal of reducing the risk of pest introduction via wood packaging.
Implementation of the international standard has apparently reduced the “approach rate” of pests in wood packaging, but not sufficiently (See my previous blog).
In this International Year of Plant Health (USDA/APHIS full citation at end of this blog), it is essential to understand how well the wood packaging program is working. Evaluating its current efficacy is especially important for protecting our forests. One key scientific society recognizes this: organizers of the Entomological Society of America’s Grand Challenges Summit in Orlando next November have chosen wood packaging as the theme.
Unfortunately,
information essential to evaluate the efficacy of ISPM#15 – both worldwide and
as implemented by USDA APHIS – is not yet available.
Our most up-to-date information on U.S. enforcement is from Kevin Harriger, Executive Director for the Agriculture Programs and Trade Liaison office, U.S. Customs and Border Protection (CBP). In his report to the annual meeting of the Continental Dialogue of Non-Native Forest Insects and Diseases in November 2019, he stated that over the past three years, CBP detected a regulated pest, on average, in 30% of wood packaging intercepted because it was not compliant with ISPM#15. Unfortunately, Mr. Harriger did not provide the actual number of shipments inspected or seized.
The absence of
specific numbers means I cannot compare the 2019 findings to previous years. My
calculation of Mr. Harriger’s data provided to the Dialogue in previous years showed
that over the nine-year period Fiscal Years 2010 through 2018, CBP detected
9,500 consignments harboring a regulated pest. Ninety-seven percent of the shipments found to be infested with a
pest bore the ISPM#15 mark. The wood packaging was from nearly all trading
countries. CBP staff say the reason for this high proportion of pests in wood
packaging is fraud.
A European study of imports of stone from China over the period 2013-2016 focused on a recognized high-risk commodity. Nevertheless, the Europeans reached the same finding: 97.5% of consignments that harbored pests bore the ISPM#15 mark. They concluded that the ISPM-15 mark was of little value in predicting whether harmful organisms were present (Eyre et al. 2018).
There is considerable dispute about which categories of packaging are most likely to be infested. The categories are pallets, crates, spools for cable, and dunnage (wood used to brace cargo and prevent it from shifting). Unfortunately, Mr. Harriger shed no light on that issue. He did report that 78% of non-compliant shipments over the last three years was in packaging associated with “miscellaneous cargo”, e.g., machinery, including electronics; metals; tile and decorative stone (such as marble or granite counter tops). This association has been true for decades (see Haack et al. 2014). Another 20% of the non-compliances were associated with fruit and vegetable cargoes. This probably reflects the combination of large volumes of produce imports from Mexico and that country’s poor record of complying with wood packaging requirements.
It has been reported that in recent years, CBP inspectors have repeatedly found pests in dunnage bearing the ISPM#15 mark and associated with “break bulk” cargo (goods that must be loaded individually; not transported in containers or in holds as with oil or grain). Ships that carry this sort of. Problems appear to be acute in Houston. While most of the criticism of non-compliant wood packaging refers to countries in Asia and the Americas, at least one of the Houston importers obtains its dunnage in Europe.
There
is even a question about the volume in incoming goods. CBD says that approximately
13 million loaded containers enter the country every year by rail, truck, air, or
sea. However, my calculation from U.S.
Department of Transportation data (see reference) was that more than 22 million
shipping containers entered the U.S. via maritime trade in 2017.
In 2017, CBP announced a new policy under which it will assess a penalty on each shipment in which the wood packaging does not comply with ISPM#15. Previously, no penalty was assessed until a specific importer had amassed five violations over a twelve-month period.
FY2019
was thus the second year under the new policy. I had hoped that Mr. Harriger
would provide information on the number of penalties assessed and any
indications that importers are strengthening their efforts to ensure that wood
packaging complies. However, he did not.
He
did report that CBP has expanded outreach to the trade. The goal is reducing
all types of non-compliance – lack of documentation, pest presence, etc. in
both wood packaging and shipping containers. Outreach includes awareness
campaigns targetting trade, industry, affiliated associations, CBP employees,
and international partners.
Still,
authorities cannot know whether the actual “approach rate” of pests in wood
packaging has changed in response to CBP’s strengthened enforcement because they
lack a scientifically valid study. The most recent study – that reported in
Haack et al. 2014 – relied on data up
to 2009 – more than a decade ago. It indicated an approach rate of
approximately 0.1% (Haack et al.
2014).
Unfortunately,
USDA APHIS has not yet accepted researchers’ offer to update this study.
We
do know that pests continue to be present in wood packaging 14 years after the
U.S. put ISPM#15 into force.
I call for:
1)
Determining the relative importance of possible causes of the persistent pest
presence problem – fraud, accidental misapplication of treatments, or other
failures of treatment;
2)
Enhanced enforcement by APHIS as well as CBP;
3)
Stepped up efforts to help US importers by APHIS and the Foreign Agricultural Service– by, e.g., providing
information on which foreign suppliers of wood packaging and dunnage have good vs. poor records; conveying importers’
complaints about specific shipments to the exporting countries’ National Plant
Protection Organizations (NPPOs), such as Departments of Agriculture;
4)
Raising pressure on foreign NPPOs and the International Plant Protection
Convention more generally to ascertain the specific reasons ISPM#15 is failing and to fix the problems identified.
Alernative Materials – Plastic!
I have also advocated for shifting at least some wood packaging – e.g., pallets and some crates – to alternative materials. For example, USDA APHIS could require exporters with bad records to use crates and pallets made from materials other than solid wood, e.g., plastic, metal, or oriented strand board. Or companies could make that shift themselves to avoid phytosanitary enforcement issues and penalties.
People recoil from the idea of using plastic and there are increasing concerns about the breakdown of plastics into tiny fragments, especially in water. But it’s also true that the world is drowning in plastic waste. Surely some of this could be recovered and made into crates and pallets with environmentally sound technology.
The Washington Post reported in November that an Israeli company is converting all kinds of trash – including food waste – into plastic, and molding that plastic into various items, including packing crates.
UBQ Materials takes in tons of rotting food, plastic bags, dirty paper, castoff bottles and containers, even broken toys. It then sorts, grinds, chops, shreds, cleans and heats it mess into first a slurry, then tiny pseudo-plastic pellets that can be made into everyday items like trays and packing crates.
Another Israeli company, Plasgad, uses plastic to make pallets, crates and other products.
Some who were skeptical now are more interested, including the president of the International Solid Waste Association and the chief executive of the Plastic Expert Group.
So – can
we address three environmental problems at the same time – mountains of waste,
methane gas releases contributing to climate change, and one (important)
pathway for the movement of tree-killing pests?
SOURCES
Eyre, D., R. Macarthur, R.A. Haack, Y.
Lu, and H. Krehan. 2018. Variation in Inspection Efficacy by Member States of
SWPM Entering
EU. Journal of Economic Entomology, 111(2), 2018, 707–715)
Haack RA, Britton KO, Brockerhoff EG,
Cavey JF, Garrett LJ, et al. (2014) Effectiveness of the International
Phytosanitary Standard ISPM No. 15 on Reducing Wood Borer Infestation Rates in
Wood Packaging Material Entering the United States. PLoS ONE 9(5): e96611.
doi:10.1371/journal.pone.0096611
Harriger, K., Department of Homeland
Security Bureau of Customs and Border Protection, presentation to the
Continental Dialogue on Non-Native Forest Insects and Diseases, November 2017.
U.S. Department of Transportation,
Maritime Administration, U.S. Waterborne Foreign Container Trade by U.S.
Customs Ports (2000 – 2017) Imports in Twenty-Foot Equivalent Units (TEUs) –
Loaded Containers Only.
U.S. Department of Agriculture, Press Release No. 0133.20, January 27, 2020
Posted by Faith Campbell
We
welcome comments that supplement or correct factual information, suggest new
approaches, or promote thoughtful consideration. We post comments that disagree
with us — but not those we judge to be not civil or inflammatory.
APHIS can protect our native & agricultural plants – but will it?
Imports
of large numbers of plants for planting from Southeast Asia represents a
significant biosecurity risk for forestry, horticulture, and natural ecosystems
in North America and Europe. This threat
is likely to grow unless APHIS takes
action under its emergency authorities.
Recent
pest introductions and related studies indicate that Southeast Asia is a newly-discovered
center of origin for plant pathogens. Places of particular concern are Vietnam,
southern Yunnan Province and Hainan Island of China, northern Laos, the eastern
Himalayas, and Taiwan. Significant pathogens and associated insects apparently centered
in these areas include the sudden oak death pathogen (Phytophthora ramorum) and other Phytophthora
species; and several ambrosia beetles and associated fungi, including the laurel
wilt fungus (Raffaelea lauricola) and
its primary vector (Xyleborus glabratus),
and the polyphagous (Euwallacea whitfordiaodendrus)
and Kuroshio shot hole borers (Euwallacea
kuroshio).
Southeast
Asia is attractive to the plant trade because of the region’s high floral diversity,
including such sought-after families as Ericaceae (rhododendrons). Indochina has
more than 10,350 vascular plant species in 2,256 genera – equaling more than
20% of the world’s plant species (Jung et
al. 2019).
Pathogens
are notoriously difficult to detect during inspections at the time of shipment.
One-time inspections of high volume imports are especially weak and prone to
failure.
How do we
protect America’s flora?
APHIS could — but has not yet — developed requirements that these countries institute integrated pest management procedures for their exporting nurseries – as provided under amendments to APHIS’ Q-37 regulation and ISPM#36. In any case, it is unlikely that such procedures would minimize the risk because many of the plants that would be imported would probably be wild-collected.
APHIS has – and should use – far more effective means to minimize risk. These are the Federal orders and listing process known as “not authorized for importation pending pest risk assessment” or NAPPRA. If – despite the scientific evidence – APHIS continues to allow high volumes of dangerous imports, the agency should immediately institute new phytosanitary controls to its inspection process. These include relying on risk-based inspection regimes and molecular high-through-put detection tools.
Supporting
Material
SOD-killed tanoaks in Big Sur; photo provided by Matteo Garbelotto, UC Berkeley
Phytophthora species
A
team of European pathologists, led by Thomas Jung and including Clive Brasier
and Joan Webber (see full citation at the end of this blog) surveyed Phytophthora species by sampling
rhizosphere soils in 25 natural and semi-natural forest stands, isolations from
naturally fallen leaves, and waters in 16 rivers in temperate and subtropical
montane and lowland regions of Vietnam during 2016 and 2017.
These
studies detected 13 described Phytophthora
species, five informally designated taxa, and 21 previously unknown taxa. Detections were made from soil samples
taken from 84% of the forest stands and from all rivers.
As I reported in am earlier blog, P. ramorum and P. cinnamomi were among those species detected. Both the A1 and A2 mating types of both P. ramorum and P. cinnamomi co-occurred.
The
survey also detected at least 15 species in other genera of oomycetes.
The
scientists conclude that most of the 35 forest Phytophthora species detected are native to Vietnam or nearby
surrounding areas, attributing species in Phytophthora
clades (taxonomically related groups) 2, 5, 6, 7, 8, 9, and 10 as native to
Indochina. Different clades were detected in high-elevation vs. lowland rivers, cooler (subtropical)
vs. tropical streams, and in soils vs. streams. Given the relatively
limited number and diversity of the sampled sites and ecosystem types, it is
likely that the true Phytophthora diversity
of Vietnam is markedly higher (Jung et al.
2019)
Worrying
diversity of Phytophthora has been
detected in other areas of Southeast Asia. A 2013 survey in natural forests and
streams of Taiwan detected 10 described species and 17 previously unknown taxa
of which 9 were of hybrid origin. In three areas in northern Yunnan, a Chinese
province adjacent to northern Vietnam, eight Phytophthora species were isolated from streams running through
sclerophyllous oak forests; two were recovered from forest soil samples. In
montane forests of the tropical island Hainan, located in the South China Sea
close to Vietnam, six Phytophthora species
were found (Jung et al. 2019).
These
studies are being conducted in the context of scientists discovering numerous
new species of Phytophthora in recent
decades. Since 1999, the number of described species and informally designated
taxa of Phytophthora has tripled. World-renowned
experts Clive Brasier anticipates that between 200 and 600 species of Phytophthora are extant in natural
ecosystems around the world (Jung et al.
2019).
In
the Vietnam survey, P. ramorum was the
most widespread species. While genetic studies indicate ancestral connections to
the four P. ramorum lineages (genetic
strains) introduced to North America or Europe, further studies are under way to clarify these relationships (Jung et al. 2019).
Jung
and colleagues found P. cinnamomi to
be the most common soilborne Phytophthora
species at elevations above 700 m. Two genotypes of the P. cinnamomi A2 mating type are causing epidemics in numerous
natural and managed ecosystems worldwide. There was some evidence that the more
frost sensitive A2 mating type might be spreading into higher altitudes in Vietnam
(Jung et al. 2019).
Most
of the Phytophthora species detected
in the rhizosphere were not associated with obvious disease symptoms. (The
principal exception was the A2 mating type of P. cinnamomi in montane forests in northern Vietnam.) (Jung et al. 2019) This lack of disease greatly reduces the chances of detecting the
oomycetes associated with any plants exported from the region – there are
no symptoms.
Since
southern Yunnan, northern Laos, and the eastern Himalayas belong to the same
biogeographic area those areas might also harbor endemic P. ramorum populations. Further surveys are needed to confirm this
hypothesis (Jung et al. 2019).
Phytophthora
lateralis
– causal agent of Port-Orford cedar root rot – also probably originated in the
area, specifically Taiwan (Vettraino et
al. 2017).
Implications for
phytosanitary measures
Many
of the native Asian forest Phytophthora
species have co-evolved with a variety of tree genera also present in Europe
and North America, including Fagaceae, Lauraceae, Aceraceae, Oleaceae, and
Pinaceae. Numerous examples demonstrate a strong potential that trees in these
families that have not previously been exposed to these Phytophthora species might be highly susceptible. Scientists have
begun an extensive host range study of Phytophthora
species from Asia and South and Central America. One part of this study found
that five Asian Phytophthora species caused
significant rot and loss of fine roots and lateral roots in three European
species of chestnut and oak (Jung et al.
2019).
Other pathogens
Studies by separate groups of scientists have concluded that several beetle-fungus disease complexes are native to this same region.
Sassafras – photo by David Moynihan
Both the laurel wilt fungus Raffaelea lauricola and its primary vector Xyleborus glabratus probably originated in Southeast Asia; there are probably different strains or genetic makeups across their wide ranges. For example, Dreaden et al. 2019 found that the fungus population from Myanmar differed genetically from those found in Japan, Taiwan, and the United States. Others had already expressed concern about the possibility that new strains of R. lauricola might be introduced (Wuest et al. 2017, cited in Cognato et al. 2019).
Cognato
et al. 2019 found that the beetle
occurs in deciduous forests from southern Japan to Northeast India, so genetic
variation across this range is likely. In fact, they have separated the species
X. glabratus into three species. They
found that some of the beetles might thrive at 40o North – the
latitude of central Illinois, Indiana, and Ohio and southern Pennsylvania. The
ability of the vector of laurel wilt disease to spread so far north poses an
alarming threat to sassafras (Sassafras albidum) – which is a major
understory tree in forests of these regions.
It is unknown whether these new species and X. glabratus lineages are associated with different fungal strains. In company with the pathologists cited above, Cognato et al. 2019 warn that preventing introduction of the three beetle species to other regions is prudent. Cognato et al. 2019 point out that if other beetle lineages from the southern extent of their range can tolerate hotter and drier conditions, they might pose a greater risk to host species in the more arid areas of California and Mexico. In addition, Central America is at great risk because of the numerous plant species in the vulnerable Lauraceae found there.
Also from the region are two beetle-fungus combinations killing trees in at least seven botanical families, including maples, oaks, and willows, in southern California. The polyphagous shot hole borer (Euwallacea whitfordiaodendrus) apparently is native to Vietnam (Eskalen et al. 2013) and the closely related Kuroshio shot hole borer (Euwallacea kuroshio) to Japan, Indonesia, and Taiwan (Gomez et al. 2018).
What you can do
Getting APHIS to act
1) communicate concern about the risk to APHIS leadership and ask that the agency take action under its NAPPRA authority
2) communicate the same to intermediaries who can influence APHIS:
State phytosanitary agency – especially through regional plant boards and National Plant Board
Your Congressional representative and senators (especially if one or more serves on Agriculture or Appropriations committee)
Professional societies – American Phytophathological Society, Mycological Society, American Society of Entomologists, Society of American Foresters …
3) communicate the same to university leadership and ask that their lobbyists advocate to USDA
4) communicate the same to the media
2) Research on extent of North American tree species’ vulnerability to the Oomycetes and other associated microorganisms
Jung et al. 2019 say that studies are under
way to identify potential pest-host relationships with important tree species.
However, all the authors are Europeans. Is anyone carrying out tests on North
American trees in the apparently most vulnerable families — Fagaceae,
Lauraceae, Aceraceae, Oleaceae, and Pinaceae?
1)
Communicate with colleagues, scientific societies, APHIS, Agriculture Research
Service, National Institute of Food and Agriculture, and USFS to determine
whether such tests are under way or planned.
2) In those cases where no studies are planned, work with above to initiate them.
Sources
Cognato,
A.I., SM. Smith, Y. Li, T.H. Pham, and J. Hulcr. 2019. Genetic Variability
Among Xyleborus glabratus Populations
Native to Southeast Asia (Coleoptera: Curculionidae: Scolytinae: Xyleborini)
and the Description of Two Related Species. Journal of Economic Entomology XX(XX),
2091, 1 – 11.
Dreaden,
T.J., M.A. Hughes, R.C. Ploetz, A. Black and J.A. Smith. 2019. Genetic Analyses
of the Laurel wilt Pathogen, Raffaelea
lauricola, in Asia Provide Clues on the Source of the Clone that is
Responsible for the Current USA Epidemic. Forests 2019, 10, 37
Eskalen,
A., Stouthamer, R. Lynch, S.C., Twizeyimana, M., Gonzalez, A., and Thibault, T.
2013. Host range of Fusarium dieback and its ambrosia beetle (Coleoptera
Scolytinae) vector in southern California. Plant Disease 97938-951.
Gomez,
D.F., J. Skelton, M.S. Steininger, R. Stouthamer, P. Rugman-Jones, W.
Sittichaya, R.J. Rabaglia, and J. Hulcr1/ 2018. Species Delineation Within the
Euwallacea fornicatus (Coleoptera: Curculionidae) Complex Revealed by
Morphometric and Phylogenetic Analyses. Insect Systematics and Diversity,
(2018) 2(6): 2; 1–11
We
welcome comments that supplement or correct factual information, suggest new
approaches, or promote thoughtful consideration. We post comments that disagree
with us — but not those we judge to be not civil or inflammatory.
valley oak at Jack London State Park (24 miles from Calistoga)
In November, scientists discovered a new ambrosia beetle in symptomatic valley oaks (Quercus lobata) trees in Calistoga, Napa County. Some blue oaks (Q. douglasii) have also been attacked (Rabaglia et al. 2020). Trees associated with this outbreak showed wilting, defoliation, and broken branches. The infested wood was discolored, presumably by the fungus. The insect, Xyleborus monographus, is native to Europe.
Officials now know that this beetle is found throughout a 15-mile-long area in Napa and neighboring Lake and Sonoma counties. It has probably been there for several years (Rabaglia et al. 2020). One specimen of the beetle was trapped in Portland, Oregon in 2018, but no infestation was detected. The beetle has never been intercepted in California. Nor has it been found in traps designed to detect bark beetles which have been deployed in 11 counties – including several in the San Francisco Bay area but not including Napa or Sonoma.
Like
all Xyleborus, adult females tunnel
into tree’s trunks, carrying fungal spores in their mycangia (structures in the
jaws in which microbes are harbored). Beetle larvae eat the fungi. Beetle
reproduction is facilitated by sibling mating within the gallery and by the
ability of unmated females to produce male offspring.
Sometimes
the beetle’s associated fungi are pathogenic to living trees. One of the fungal
species detected in the Calistoga infestation is Raffaelea montetyi, which is reported to be pathogenic to cork oak.
The presence of this fungus had been reported in 2018, although the beetle
species carrying it was not identified then. This is apparently the first report
of this fungus in North America.
Known
hosts of beetle X. monographus include
European or Eurasian chestnut (Castanea
sativa), beech (Fagus orientalis),
and European and American oaks (including
Q. lobata and Q. rubra). The possible effects of the beetle and
associated fungi on other oak species is unknown. Oaks are acknowledged to be important
components of forests and woodlands in California. Ambrosia beetles often attack
stressed trees. Since California forests are increasingly frequently stressed
by drought, fire, and other pests, they might be especially vulnerable.
The California Department of Food and Agriculture is currently seeking comments on what pest rank to assign the insect. The comment period closes on March 6th and I encourage you to consider providing your views.
In
their draft document ranking risk, state officials note that a proven host — Q. lobata — is widespread in California
and the insect is probably capable of establishing over much of the state. The possible
economic impact was described as possibly affecting production of oaks in California
nurseries and triggering quarantines. (Does
this mean CDFA expects impacts only on saplings? Is this realistic? CDFA made
no mention of costs to urban areas for hazard tree management.)
The risk assessment notes that research by McPherson, et al. (2008) found that ambrosia beetles are attracted to oak trees already infected with sudden oak death (SOD) (Phytophthora ramorum). Therefore, X. monographus could have a synergistic impact with SOD on California oaks – which has already killed an estimated 1.9 to 3.3 million coast live and Shreve oaks.
SOURCE
Rabaglia, R.J. S.L. Smigh, P. Rurgman-Jones, M.F. Digirolomo, C. Ewing, and A. Eskalen. 2020. Establishment of a non-native xyleborine ambrosia beetle, Xyleborus monographus (Fabricius) (Coleoptera: Curculionidae: Scolytinae), new to North America in California. Zootaxa 478 (2): 269-276
Posted
by Faith Campbell
We
welcome comments that supplement or correct factual information, suggest new
approaches, or promote thoughtful consideration. We post comments that disagree
with us — but not those we judge to be not civil or inflammatory.
exit hole of Anapolophora chinensis in Chinese penjing from circa 2001
APHIS has released a risk assessment in response to a petition from the Republic of Korea (ROK) seeking permission to export to the United States bunjae of three maple species (Acer buergerianum Miq., A. palmatum Thunb., and A. pseudosieboldianum Nakai). The risk assessment is available here. Scroll down to the deadline February 3.
Comments are accepted until 3 February. To comment, send an email to PPQPRAcomments@aphis.usda.gov. Include the name of the commodity assessed by the draft document (e.g., Korean maple bunjae) in the Subject line.
“Bunjae”
is the Korean term for plants for planting equivalent to Japanese “bonsai” or
Chinese “penjing”. In this practice,
trees are grown – often for years – using cultivation techniques such as
pruning, root reduction, potting, defoliation, and grafting, to produce
miniature specimens.
Importation of bunjae plants for planting in the Acer genus from several Asian countries was prohibited temporarily under the agency’s authority under the Plant Protection Act and regulations in 7 CFR 319.37, Subpart H- P4P to limit imports of a new suite of plant taxa as “not authorized pending pest risk analysis” (NAPPRA).
The NAPPRA listing, finalized in 2013, followed numerous detections of Anoplophora and possibly other pests in penjing shipped from China to the United States, and one outbreak (in Takohma, Washington) that required expensive and destructive eradication measures. At that time, APHIS made the case that no effective mitigation existed to provide protection adequate to the risk. If APHIS is to agree to the ROK petition, it must demonstrate that any mitigation measures it accepts have overcome deficiencies identified in the original proposal to include Acer in the NAPPRA category.
APHIS will address risk management aspects, including and risk mitigation
measures, after it has assessed stakeholder and country comments on each pest
list or risk assessment. There will be an opportunity to comment on any proposed
mitigation measures later.
The
risk assessment now open for comment clearly demonstrates that the risks are
severe. It concludes that 17 or 18 taxa or groups of species pose a “high”
overall risk of introduction, establishment, and impacts. Another 10 pose an overall “moderate” risk.
In each case, the risk assessors concluded that the harvest and shipment
procedures outlined in Section 1.4 of the Korean petition would not mitigate
the risk.
While the risk is greatest for maples (Acer spp.), many other types of plants also host pests evaluated in the risk assessment. Thus, the risk often affects fruit trees and grapes as well as alders, birches, dogwoods, elms, magnolias, oaks, poplars, walnuts, willows, rhododendron, even redwood.
My questions and concerns
I note that Table 3 of the risk assessment omits the Asian longhorned beetle (Anoplophora glabripennis), even ‘tho the species is discussed in the text and received an overall risk ranking of “high”. Is this a mistake? If the omission is deliberate, why is the reasoning not discussed in the risk assessment?
The assessments included in this document are brief and leave out many easily obtainable facts regarding damage, especially with regard to the Anoplophora, Lymantria, and Lycorma genera. The risk assessment notes when pest species are polyphagous, but it is uncertain how it incorporates that heightened risk of potential damage.
eradication clearcuts in Takoma, Washington in 2001 reason: escape of A. chinensis from Chinese penjing plants while they were in “post entry quarantine”
I
am also concerned about the document’s treatment of uncertainty. First, “moderate uncertainty” is defined as
“Additional or better evidence may or may not change rating.” How do the
assessors evaluate this 50/50 tossup? My
concern is heightened by a statement in the text regarding two taxa, Cacopsylla albopontis & C. pseudosieboldiani. The assessment
notes an absence of literature documenting that these taxa are pests in their
native range, so their ability to cause damage if introduced to the U.S. is
unknown. Consequently, the assessors did not analyze them further “as they are
unlikely to cause unacceptable impacts.” As we all know, numerous arthropods
and pathogens highly damaging in naïve environments – including in the US — were
not pests / were barely known in their native ranges.
Regarding individual species, I note that the assessment says the wood-root fungus Daedalea dickinsii is usually found in older heartwood of roots, trunks, or branches. The assessors conclude that it is unlikely that this fungus would be associated with maple seedlings. However, bunjae trees are not seedlings; they are deliberately miniaturized woody plants that are often years old.
Re: Anomala cuprea, the assessor seems to downplay the risk because the insect lacks a specific attraction to maples. While I agree that a generalist might be somewhat less likely to be on the bunjae when they are exported, a generalist might pose a threat to a wide range of woody plants if introduced. This higher level of possible impacts needs to be recognized in the assessment.
Several
insect groups were excluded from further valuation despite being described as
established in Korea and “only associated with Acer species”. Included in this group are several beetles, true
bugs (including aphids and leafhoppers), and butterflies/moths (pp. 13-14 of
the PRA). I found this language to be completely unclear. If the pests are in
Korea and associated with maples, why were they not evaluated?
Posted
by Faith Campbell
We
welcome comments that supplement or correct factual information, suggest new
approaches, or promote thoughtful consideration. We post comments that disagree
with us — but not those we judge to be not civil or inflammatory.
rust on `ohi`a; photo by J.B Friday, University of Hawaii
As I blogged in December, APHIS is seeking input on a proposal to place several plant taxa in the category “not authorized pending pest risk analysis” (NAPPRA). The purpose of this proposed listing is to prevent introduction of plant pests or probable invasive plant species.
I urge you to comment before the deadline – this Friday, January 24.
In
comments prepared for the Center for Invasive species Prevention (CISP), I
applauded APHIS’ continued reliance on this authority to improve phytosanitary protections
for our natural and agricultural resources. I noted, however, several
weaknesses in the proposal – including several pathogens that I think should
have been included, but were not. I summarize these comments here.
1)
There have been lengthy delays in proposing and finalizing lists of species to
be regulated under this authority. While I strongly support listing of all
plants in the family Myrtaceae that are destined for Hawai`i in order to reduce
the risk that additional strains of the `ohi`a rust pathogen Austropuccinia psidii might be
introduced and prove more damaging to native Hawaiian vegetation than the
strain already present on the islands. However, this proposal comes 15 years
after the pathogen was detected in Hawai`i and six years after publication of
scientific documentation of the existence of more damaging strains of the
pathogen.
2)
When lists have been presented, they failed to include all appropriate species.
I
am disturbed that APHIS did not include in the NAPPRA proposal Ceratocystis lukuohia and Ceratocystis huliohia, two pathogens that
are killing millions of ‘ōhi‘a trees in Hawai`i under the name “rapid ‘ōhi‘a death”.
3)
APHIS must act under other regulatory provisions to close some of the gaps left
by this proposal.
The listing of plants in the Myrtaceae
(see number 1 above) under NAPPRA does nothing to halt imports of cut flowers
and foliage, which are widely recognized to be the pathway by which the rust
was introduced to Hawai`i. APHIS notes
that is should act under other regulatory authority to close this pathway; I
hope you will urge APHIS to take such action quickly, preferably initially by
issuing a Federal Order.
4) APHIS has proposed 26 plant taxa for
inclusion in the NAPPRA category because they might themselves be invasive. These
proposals are generally well supported and deserve your support. Several plant
taxa appear to pose significant ecological threats: two taxa of mangroves (Bruguiera gymnorhiza and Lumnitzera racemose); a vine that grows
in Asian and Indian Ocean mangrove forests,
Derris trifoliate; and several aquatic plants (Crassula helmsii, Elatine ambigua, Luziola subintegra, Philydrum lanuginosum, Stratiotes
aloides); and Ligustrum robustum.
Remember that at least 50 species of aquatic plants are already considered invasive in the United States. At least eight species of Ligustrum are also invasive.
Update: Listing finalized
On June 2, 2021 APHIS finalized the NAPPRA listing originally proposed in November 2019.
The agency added to the category 26 plant taxa because they are invasive; all plants in the Myrtaceae family when destined to Hawai`i, and 43 other plant taxa that are hosts of 17 quarantine pests.
The only change from the proposed action was to drop listing of the subfamily Bambusoideae because it is already regulated under NAPPRA to prevent introduction of other quarantine pests.
APHIS had received 132 comments from producers, importers, industry groups, conservationists, scientists, plant pathologists, ecologists, administrators, teachers, students, and private citizens. Most reportedly supported the proposed listing of Myrtaceae destined for Hawai`i and expressed no concerns about the proposed listing of most other taxa. I have blogged previously about the threat to Hawaii’s unique flora posed by the pathogenAustralopuccinia psidii (the subject of this NAPPRA listing) and other non-native organisms – here and here.
We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.
For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report at http://treeimprovement.utk.edu/FadingForests.htm
SOD in California; photo by Joseph O’Brien. courtesy of Bugwood
We know that the international trade in living plants is a major pathway by which tree-killing pathogens are being spread – some of them again and again. According to Grünwald etal. (2019), Phytophthora ramorum, the pathogen that causes Sudden Oak Death (SOD), has been introduced to North America and Europe – probably from Asia – at least five times. One lineage or genetic strain – EU1 – has been established on both continents (strains explained here). There is strong evidence of two separate introductions to Oregon, at least 12 to California.
Jung
et al. 2015 state definitively that
the international movement of infested nursery stock and planting of
reforestation stock from infested nurseries have been the main pathway of
introduction and establishment of Phytophthora
species in European forests.
Clive Btasier in Vietnam photo from UK Forest Research
Jung et al. 2020 have demonstrated that P. ramorum probably originated in
Vietnam. This region appears to be a center of
diversity for Phytophtoras and other
Oomycetes: baiting of soil and streams resulted in the detection of 13
described species, five informally designated taxa, and 21 previously unknown
taxa of Phytophthoras plus at least
15 species in other genera. Noting the risk associated with any trade in plants
from this region, the authors re-iterated past appeals that the international
phytosanitary system replace the “outdated and scientifically flawed
species-by-species regulation approach based on random visual inspections for
symptoms of described pests and pathogens” by instituting “a sophisticated
pathway regulation approach using pathway risk analyses, risk-based inspection
regimes and molecular high-throughput detection tools.”
Pathogen’s Spread Proves U.S.
Domestic Regulations Governing Nursery Trade Are Inadequate
Last year I blogged about the most recent spread of Phytophthora ramorum through the nursery trade. As of now, we know that shipments of potentially infected plants had been sent to 18 states. Infected stock had been detected in nurseries in seven of these (Iowa, Illinois, Indiana, Kansas, Missouri, Nebraska, Oklahoma) plus the source state, Washington [COMTF Newsletter August 2019].
Since then, I learned [COMTF newsletter for December 2019] that these plants were infected by the NA2 strain of the pathogen. This is the first time that this strain has been shipped to states outside the West Coast. It is unclear what the impact will be if – as is likely – infested plants are still extant in purchasers’ yards. Both the NA1 strain (the strain established in most infested forests of California and Oregon) and the NA2 strain belong primarily to the A2 mating type, so the potential spread of NA2 lineages might not exacerbate the probability of sexual reproduction of the pathogen.
I applaud agencies’ funding of
genetic studies to determine the lineage of the pathogen involved. It not only
helps narrow the possible sources of infected plants, but also could be
important in determining risk and management options.
I have long criticized USDA’s P. ramorum regulatory program – see Fading Forests III and my blogs discussing the most recent revisions to the regulations here and here. I believe that both the earlier regulations and the revisions finalized last May provide inadequate protection for America’s forests.
The updated regulations do take a couple of important positive steps. First, APHIS is now authorized to sample water, soil, pots, etc. – and to act when it finds evidence of the pathogen’s presence. APHIS also now mandated nurseries found to be infested to carry out a “critical control point analysis” to determine practices which facilitated establishment and persistence of P. ramorum.
However, these improvements are
severely undermined by continuing the five-year-old practice of limiting close
scrutiny to only those nurseries that tested positive for the pathogen in the
recent past. The flaw in this approach was starkly demonstrated by the
pathogen’s spread in 2019. The Washington State nursery that was the source of
the infected plants had not previously been positive, so it was under routine
nursery regulation, not the more stringent federal P. ramorum program.
Too often various iterations of the regulations have allowed infected plants to be shipped. Between 2003 and 2011, a total of 464 nurseries located in 27 states tested positive for the pathogen, the majority as a result of shipments traced from infested wholesalers (Campbell). The number of nurseries found to have infected plants has since declined, but not dropped to zero. These include 34 nurseries in 2010 (COMTF February 2011 newsletter), 21 in 2012, and 17 in 2013 (Pfister). During 2014, state inspectors detected the SOD pathogen in 19 nurseries – 11 in the three west-coast states and eight in other parts of the country (Maine-1, New York-2, Texas-1, and Virginia-4) COMTF newsletter December 2014). Despite the continuing presence of the pathogen in the nursery trade, APHIS formalized existing practices that narrowed the regulators’ focus to only those nurseries with a history of pathogen presence. This approach has been shown to fail – we need APHIS and the states to find a way to broaden their scrutiny.
The most immediate impact of the continuing presence of P. ramorum in the nursery trade is the burden borne by eastern states’ departments of agriculture. They are obligated to seek out in-state nurseries that might have received infected plants; inspect those plants; and destroy the infected plants, test nearby plants, and try to find and retrieve plants that had been sold. The heaviest, and most direct, burden is borne by the receiving nurseries. Anger about bearing this burden for 15 years doubtless prompted the National Plant Board to adopt a tart resolution calling on APHIS to carry out a review of its communications to the states during the 2019 incident. The NPB also questioned whether current program processes and guidance are effective in preventing spread of this pathogen.
Unfortunately, the NPB had not
commented formally on the rule change when it was proposed.
The states’ frustration is
exacerbated by the fact that under
the Plant Protection Act, when APHIS takes a regulatory action it prevents
states from adopting more stringent regulations. While the law allows for
exceptions if the state can demonstrate a special need, none of the five
applications for an exemption pertaining to P.
ramorum was approved (Porter and Robertson 2011). I have been unable to
find evidence of petitions submitted in the nine years since 2011.
In Case You Needed A
Reminder: P. ramorum is a Dangerous Pathogen
– as Proved by the Situation in the West states and Abroad
Continuing Intensification of the Already Bad Infestations in the West
tanoak mortality in Big Sur photo courtesy of Matteo Garbelotto, UC Berkeley
As of 2014 (see COMTF November 2018 newsletter available here), perhaps 50 million trees had been killed by P. ramorum in California and Oregon. The vast majority were tanoaks (Notholithocarpus densiflorus) – an ecologically important tree.
Since
2014, the disease has intensified and spread in
response to recent wet winters. In 2016 (see COMTF
November 2016 newsletter here) disease was detected for the first time in a fifteenth California county and new outbreaks or more severe infestations were recorded in seven other counties. In 2019, SOD was detected in the sixteenth county. Tanoak mortality in California increased by more than 1.6 million trees across 106,000 acres in 2018.
Perhaps more disturbing, the disease has also intensified on the eastern side of San Francisco Bay – an area thought to be less vulnerable because it is drier and where there are fewer of the principal sporulation host, California bay laurel (see COMTF March 2017 newsletter here).
A second disturbing event is the detection in Oregon forests of the EU1 strain of Phytophthora ramorum. The August 2015 detection was the first instance of this strain being detected in a forest in North America. Oregon authorities prioritized removing EU1-infected trees and treating (burning) the immediate area, which had expanded to more than 355 acres – all within the quarantine area in Curry County. The legislature provided $2.3 million for SOD treatments for 2017-2019 (Presentation by Chris Benemann of Oregon Department of Agriculture to the Continental Dialogue on Non-Native Forest Insects and Diseases; reported here).
The EU1 lineage is a different
mating type than the NA1 lineage already established in Oregon. Scientists
should study P. ramorum populations
in Vietnam and Japan, where both mating types are present, to determine whether
they are reproducing sexually. There is also the risk that the EU1 lineage
might be more aggressive on conifers – as it has been in the United Kingdom (Grünwald etal. 2019).
The EU1 infestation was introduced to the forest from a nursery. The nursery had carried out the APHIS-mandated Confirmed Nursery Protocol, then closed. I ask, what does this apparent transmission from nursery to forest say about the risk of transmission? Does it raise questions about the efficacy of the confirmed nursery protocol to clean up the area? Remember that a pond at the botanical garden in Kitsap, Washington has repeatedly tested positive, despite several applications of the clean-up protocols.
(For a discussion of the implications of mixing the various strains of P. ramorum, visit here)
These disasters remind us how sad it
is that California and federal officials did not adopt aggressive management
efforts aimed at slowing the pathogen’s spread at an early stage of the epidemic. Experts on modeling the
epidemiology of plant disease concluded three years ago that the sudden oak
death epidemic in California could have been slowed considerably if aggressive and
well-funded management actions had started in 2002 (Cunniffe, Cobb,
Meentemeyer, Rizzo, and Gilligan 2016).
The Oregon Department of Forestry commissioned a study of the economic impact of the P. ramorum infestation that found few economic impacts to date, but potentially significant impacts in the future. It also noted potential harms to tribal cultural values and the “existence value” of tanoak-dominated forests and associated obligate species.
Situation Abroad
The situation in Europe is even worse than in North America. Two strains of P. ramorum are widespread in European nurseries and in tree plantations and wild heathlands of western the United Kingdom and Ireland. and here and here. Jung et al. 2015 found 56 Phytophthora taxa in 66% of 2,525 forest and landscape planting sites across Europe that were probably introduced to those sites via nursery plantings.
larch plantation in UK killed by P. ramorum photo from UK Forest Research
In Australia, Phytophthora dieback has infected more than one million hectares in Western Australia. More than 40% of the native plant species of the region are vulnerable to the causal agent,P. cinnamomi
Barber
et al. 2013 reported 9 species of Phytophthora associated with a wide variety
of host species in urban streetscapes, parks, gardens, and remnant native
vegetation in urban settings in Western Australia. Phytophthora species were recovered from 30% of sampled sites.
In
New Zealand, the endemic – and huge, long-lived – kauri tree (Agathis australis) is also suffering
severe impacts from Phytophtoras and
other pathogens (Bradshaw et al.
2020)
See
the IUFRO Working Party 7.02.09 ‘Phytophthora Diseases of Forest Trees’ global
overview (Jung et al. 2018), which covers
13 outbreaks of Phytophthora-caused
disease in forests and natural ecosystems of Europe, Australia and the
Americas.
The situation in
the Eastern United States is Unclear
After 15 years of the nursery trade carrying P. ramorum to nurseries – and possibly yards and other plantings – in states east of the 100th Meridian, what is the risk that these forests will become infested? No one knows. We do known that the pathogen has been detected from 11 streams in six eastern states – four in Alabama; one in Florida; two in Georgia; one in Mississippi; one in North Carolina; and two in Texas. P. ramorum has been found multiple times in eight of these streams – two steams in Alabama, one each in Mississippi and North Carolina (see COMTF April 2019 newsletter available here). While established vegetative infections have not been detected, the question remains: how is the pathogen persisting? Scientists agree that P. ramorum cannot persist in the water; it must be established on some plant parts (roots?) or in the soil. Still, Grünwald etal. (2019) report that there is little evidence of plant infections resulting from stream splash in Oregon.
Unfortunately, fewer states are participating in the stream surveys – which are operated by the USDA Forest Service. In 2010, 14 states participated; in 2018, only seven (Alabama, Georgia, Mississippi, North Carolina, Pennsylvania, South Carolina, and Texas). Florida and Tennessee recently dropped out. The number of streams surveyed annually also has dropped – from 95 at the highest to only 47 in 2018 (see COMTF April 2019 newsletter available here). This reduced scrutiny makes it less likely that any infestation on plants will be detected. Risk maps (reproduced in Chapter 5 of Fading Forests III here) developed over more than a decade indicate that forests in the southern Appalachians and Ozarks are vulnerable to SOD.
Risks to other
plants
The risk from Phytophthoras is not just P. ramorum and trees! Swiecki et al. 2018 report a large and increasingly diverse suite of introduced Phytophthora species pose an ever greater threat to both urban and non-urban plant communities in California. These threats are linked to planting of nursery stock. See also the information posted here.
Jung et al. 2018 cite numerous other authors’ findings of multiple Phytophthoras in Oregon and. California nurseries as well as in nurseries in various eastern states.
Nor is Phytophthoras the only pathogenic genus to pose a serious risk to America’s trees. I remind you of the fungus Fusariumeuwallacea associated with the Kuroshio and polyphagous shot hole borers, which is known to kill at least 18 species of native plants in California and additional species in South Africa. The laurel wilt fungus kills many trees and shrubs in the Lauraceae family. ‘Ohi‘a or myrtle rust kills several shrubs native to Hawai`i and threatens a wide range of plants in the Myrtaceae family in Australia and New Zealand; rapid ‘ohi‘a death fungi (Ceratocystis huliohia and Ceratocystis lukuohia) [All described here] are killing the most widespread tree on the Hawaiian Islands.
Solutions – complete &
implement modernized international and domestic phytosanitary regulations
Clearly,
standard phytosanitary practice of regulating pests known to pose a threat
does not work when many – if not most – of the damaging pests are unknown to
science until introduced to a naïve ecosystem where they start causing
noticeable levels of damage. We need a more proactive approach – as has long been
advocated by forest pathologists, including Clive Brasier 2008 and later,
Santini et al. 2013, Jung et al. 2016, Eschen et al. 2017.
National and international phytosanitary agencies have taken some steps toward adopting policies and programs that all hope will be more effective in preventing the continued spread of these highly damaging tree-killing pests. First, APHIS has had authority since 2011 – through the Not Authorized for Importation Pending Pest Risk Assessment (NAPPRA) program — to prohibit temporarily imports of plants suspected of transporting known damaging pathogens until the agency has conducted a pest risk analysis. However, utilization has lagged: only three sets of species have been proposed for listing in NAPPRA in the eight and a half years since the program was instituted in 2011. The third list of proposed species is currently open for public comment.
Another
weakness is that the program still focuses on organisms known to pose a risk.
Second, in 2018 APHIS completed a decades-long effort to revise its plant import regulations (the “Q-37” regulations). APHIS now has authority to require foreign suppliers of living plants to carry out “hazard analysis and critical control point” programs and adopt integrated pest management strategies to ensure that the plants are pest-free during production and transport.
However, implementation of this new
authority depends on APHIS negotiating agreements with individual countries
that would govern specific types of plants exported to the U.S. APHIS has not
yet announced completion of any programs under this authority. Nor is it clear
which taxa or countries APHIS will prioritize.
APHIS’ action was anticipated by the international plant health community. In 2012, member states in the International Plant Protection Convention adopted International Standard for Phytosanitary Measure 36 (ISPM#36) The standard sets up a two-level system of integrated measures, which are to be applied depending on the pest risk identified through pest risk analysis or a similar process. The “general” integrated measures are widely applicable to all imported plants for planting. The second level includes additional elements designed to address higher pest-risk situations that have been identified through pest risk analysis or other similar processes.
However,
the preponderance of international efforts to protect plant health continues to
rely on visual inspections that look for species on a list of those known to be
harmful. Yet we know that most damaging Phytophthoras
were unknown before their introduction to naïve ecosystems.
Furthermore,
use of fungicides and fungistatic chemicals – that mask infections but do not
kill that pathogen – is still allowed before shipment.
(For more complete analyses of the Q-37 revision and ISPM#36, see chapters five and four, respectively, of Fading Forests III.)
The
nursery industry is working with state regulators and APHIS to develop a voluntary
program utilizing integrated measures –
the Systems Approach to Nursery Certification (SANC) program. https://sanc.nationalplantboard.org/
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