forest pathogens – Page 14 – Center for Invasive Species Prevention

APHIS’ Proposed Sudden Oak Death Rule – Ignored by Too Many Stakeholders!

P. ramorum-infected seedlings in a nursery; photo by USDA APHIS

As I blogged on 2 August, the USDA Animal and Plant Health Inspection Service (APHIS) is proposing to update its regulations intended to prevent spread of the sudden oak death (SOD) pathogen (Phytophthora ramorum) via movement of nursery stock. The proposal is to incorporate into formal regulations several changes made through temporary “Federal Orders” issued in 2014 and 2015. This might sound boring – but it was actually an important opportunity to press APHIS to correct weaknesses in its current regulatory system. Whether APHIS’ ultimate program is weak or strong will affect how well we protect our forests against every kind of pest, not just SOD.

Unfortunately, few organizations seized this opportunity. Comments were submitted by only five organizations and three individuals. The organizations were the Center for Invasive Species Prevention, California Oak Mortality Task Force, several nursery industry associations in a joint comment, and the state departments of agriculture from Florida and Pennsylvania. It is most unfortunate that the other states appear to have given up on influencing APHIS’ decisions and did not comment. (Given the long history of APHIS failure to support states trying to adopt protective regulations – as described in Chapter 3 of my report Fading Forests III, available here – perhaps this is understandable.)

The Pennsylvania Department of Agriculture (DoA) was quite critical of the proposal in its comments. It complained that APHIS is not consistent in the way it regulates various quarantine pests and the vectors on which they might be transported. Allowing shipping nurseries to submit fewer samples for testing and providing less regulatory oversight does not help protect receiving states such as Pennsylvania.

The Pennsylvania DoA noted that the Plant Protection Act has a preemption clause which prevents states from adopting regulations more stringent than those instituted by APHIS. 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 has been approved. (The Environmental Law Institute addressed this issue in 2011; see source at end of the blog.)

Copies of all comments can be viewed here. Their main critiques of APHIS’ proposal include:

1) APHIS should mandate sampling at all nurseries selling SOD host or associated host plant species.

While any nursery that contains or sells host or associated host plant species can become infected, APHIS does not have any system for detecting P. ramorum in such nurseries which have been infection-free for three years. This point was made by CISP and the California Oak Mortality Task force (COMTF).

1(a) Risk associated with Nurseries in the Quarantine Zone

The Florida Department of Agriculture (FDACS) objected to allowing interstate shipment of any plants – both host and non-host species – from nurseries in the quarantine zones of California and Oregon. FDACS notes that where P. ramorum is in the natural environment, it is essentially impossible to be certain that available inoculum is not in the water column or soil and thus potentially to being shipped with containerized plants.

2) Level of risk.

APHIS says that the current regulations have reduced the risk of spread of P. ramorum via the nursery trade to a low risk. APHIS cites the fact that over a nine-year period (2004 – 2013), P. ramorum was detected at a “very small percentage—usually no more than 3 percent annually” of nurseries inspected under the current program. To the contrary, I (on behalf of CISP) argue that an annual level of risk of three percent is not a low level of risk, the nursery industry’s comments accept this level of risk as “low”.

3) Inspection, Sampling, and Certification Protocols

The Pennsylvania Department of Agriculture objects that while APHIS admits the pathogen might be transmitted in media, soil, water, potted material and containers, the proposed rule does nothing to assist states in protecting themselves from pathogen transport via these vectors. Pennsylvania DoA asked APHIS to provide greater oversight so as to ensure consistency in inspection and certification procedures.

I, on behalf of CISP, said all decisions should be based on sampling and testing of water, soil, growing media, pots, and plants (leaves, stems, roots). They should not rely only on visual inspection of plants.

The Florida Department of Agriculture did not address the certification procedure directly, but objected to allowing shipment of lots of plant material determined to be free of P. ramorum from a nursery in which infected plants have been detected. FDACS pointed out that infected plants could slip through because they were asymptomatic at the time of inspection or because leaves dropped from nearby infected plants contaminated the soil.

4) Updates to the List of Hosts Should Be Comprehensive

As I noted in my previous blog, APHIS’ proposed update does not include more than a dozen species growing in the wild or in gardens in the Pacific Northwest that scientists have identified as hosts of P. ramorum; and would designate Japanese larch (Larix kaempferi) as only an “associated” host.

The California Oak Mortality Task Force raised similar issues and warned that unexplained gaps in the host list cause unnecessary confusion and undermine the scientific foundation of regulations.

Source

Porter, R.D. and N.C. Robertson. 2011. Tracking Implementation of the Special Need Request Process Under the Plant Protection Act. Environmental Law Reporter. 41.

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.

Farm Bill Update – Please Thank Your Senators Right Away!

U.S. Senate

In May I blogged about adoption by the House of Representatives of its version of the Farm Bill, which will govern a wide range of policies for the next five years. I reported that the bill included weakened versions of a provision CISP has been seeking to establish programs to support long-term strategies to counter non-native, tree-killing insects and pathogens, e.g., biocontrol and breeding of trees resistant to pests.

I also reported that the House Farm bill contains provisions to which there is significant opposition from the larger environmental community. Several would gut some of our country’s fundamental environmental laws which have protected our health and natural resources since the early to mid-1970s. These provisions would:

Allow the U.S. Forest Service and the Interior Department’s Bureau of Land Management to decide for themselves whether an activity might “jeopardize” an endangered species (eliminating the need to consult with the U.S. Fish and Wildlife Service or National Marine Fisheries Service) (Section 8303 of the House Bill);
Allow the U.S. Forest Service and Bureau of Land Management to avoid preparing an environmental assessment under the National Environmental Policy Act (NEPA) for a long list of actions which currently must be assessed. That is, they could claim a “categorical exclusion” when taking a wide variety of “critical” actions aimed at addressing several goals. These include countering insect and disease infestations, reducing hazardous fuel loads, protecting municipal water sources, improving or enhancing critical habitat, increasing water yield, expediting salvage of dead trees following a catastrophic event, or achieving goals to maintain early successional forest. These “categorical exclusions” would apply to projects on up to 6,000 acres. (Sections 8311 – 8320); and
Require the EPA Administrator to register a pesticide if the Administrator determines that the pesticide, when used in accordance with widespread and commonly recognized practices, is not likely to jeopardize the survival of a species listed under the Endangered Species Act or to alter critical habitat. That is, the Administrator would not be required to consult with the U.S. Fish and Wildlife Service or National Marine Fisheries Service when making such determinations unlike under current law. (Section 9111).

The Senate passed its version of the Farm Bill in late June. Unfortunately, the Senate bill does not include the long-term restoration program CISP seeks. However, it doesn’t include the above attacks on environmental laws, either.

With the current Farm Bill set to expire on September 30^th, there is considerable pressure to adopt a final version soon. House and Senate staffers have been meeting to find common ground. Representatives and Senators who are on the joint Conference Committee – charged with working out the final bill – will hold their first meeting next week, on September 5^th.

In preparation for the meetings of the Conference Committee, 38 Senators have written to their two colleagues who will lead the Senate conferees. Their letter voices strong opposition to changing long-standing environmental law:

“These harmful riders, spread throughout the Forestry, Horticulture, and Miscellaneous titles of the House bill, subjected the legislation to unnecessary opposition on the House floor and now complicates [sic] the bipartisan cooperation needed to pass a final conference report.

Again, we write to express our strong opposition to gutting bedrock U.S. environmental and public health protections with provisions that threaten our air, water, lands, and wildlife.”

Senators signing the letter are:

California: Feinstein & Harris; Colorado: Bennet; Connecticut: Murphy & Blumenthal; Delaware: Carper & Coons; Florida: Nelson; Hawai`i: Hirono & Schatz; Illinois: Durbin & Duckworth; Maryland: Cardin & Van Hollen; Massachusetts: Warren & Markey; Minnesota: Klobuchar & Smith; Michigan: Peters; Nevada: Cortez Masto; New Hampshire: Shaheen & Hassan; New Jersey: Menendez & Booker; New Mexico: Udall & Heinrich; New York: Gillibrand; Oregon: Wyden & Merkley; Pennsylvania: Casey; Rhode Island: Reed & Whitehouse; Vermont: Sanders; Virginia: Warner & Kaine; Washington: Murray & Cantwell; Wisconsin: Baldwin.

If your Senators signed the letter, please email, call, or write to thank them immediately. If your Senators didn’t – please urge them to express their support for its content.

Posted by Faith Campbell

APHIS’ New Sudden Oak Death Rule – Input from Experts Critically Needed

P. ramorum-infected rhododendron

Jennifer Parke, Oregon State University

The USDA Animal and Plant Health Inspection Service (APHIS) is proposing to update its regulations intended to prevent spread of the sudden oak death (SOD) pathogen (Phytophthora ramorum) via movement of nursery stock. The proposal would incorporate into formal regulations several changes made through temporary “Federal Orders” issued in 2014 and 2015. The deadline for comments is August 24. Copies of the proposal and the on-line instructions to comment are located here.

[Federal Orders are issued by APHIS without going through the usual regulatory process. Federal Orders take effect immediately. Federal Orders are issued by the APHIS Deputy Administrator under the authority of the Plant Protection Act Section 412(a), 7 U.S.C. 7712(a). The Act authorizes the Secretary of Agriculture to prohibit or restrict the movement in interstate commerce of any plant, plant part, or article if the Secretary determines the prohibition or restriction is necessary to prevent the dissemination of a plant pest within the United States. Federal Orders also apparently modify existing regulations promulgated under the PPA and found in the Code of Federal Regulations.]

[I stated my objections to the relaxed approach under the Federal orders back in 2015; see my blog here .]

While I applaud APHIS’ decision to focus on nurseries, I have serious concerns about several aspects of the existing program that APHIS now proposes to formalize in the new regulation. I will ask that the following changes be made before the rules are made final. Please consider doing the same.

The Problems

1) APHIS should use this regulatory action to mandate sampling at all nurseries selling SOD host or “associated host” plant taxa

APHIS does not have any system for detecting P. ramorum in nurseries not previously suspected to harbor the pathogen. Instead, APHIS and its state cooperators inspect only those nurseries at which infected plants have been detected in recent years. This is a major weakness in the existing regulation and in the proposal. APHIS cannot limit the spread of SOD without periodically surveying nurseries outside the quarantine zone that contain or sell host or associated host taxa but where P. ramorum has not already been found.

History shows that unexpected nurseries can become infected. In 2012, half of the infected nurseries identified by regulators were infected for the first time. (These nursery infections were detected as a result of “trace-forwards” of infected plants shipped by wholesale nurseries.) Detection of all infected nurseries is vital to identifying the nurseries that were the original source of infection through trace-back. Also, finding infections early provides the best chance to protect the environment in which the infected nursery operates and in which its plants are used.

1(a) It is particularly important to survey nurseries within climate zones that support the pathogen.

It is well established that environmental conditions along parts of the Pacific coast of California, Oregon, and probably Washington are especially conducive to persistence and spread of P. ramorum. Certain regions of eastern states also appear to have climatic conditions conducive to survival of the pathogen – as documented in the several risk maps prepared over the past two decades. Such areas would be smaller than the old “regulated areas” (see below), and more closely tied to climate zones – but larger than the actual quarantine zone.

[Under the pre-2014federal regulations, certain geographic regions were designated as “regulated areas”. These areas were defined as those in which P. ramorum has been found on nursery stock in commercial nurseries, but not found in the natural environment. These “regulated areas” included those parts of California and Oregon that are not inside quarantined areas, as well as the entire State of Washington. Under the 2014 and 2015 Federal Orders, APHIS has already dropped this geographic designation, and now focuses regulations only on nurseries at which infected plants have been detected in recent years.]

2) APHIS needs to set a more protective level of risk.

APHIS tries to persuade us that the current regulations have reduced the risk of spread of P. ramorum via the nursery trade to a low risk. As proof, APHIS says that over a nine-year period (2004 – 2013), APHIS and the state plant protection authorities detected P. ramorum at a “very small percentage—usually no more than 3 percent annually” of nurseries inspected under the current program. However, an annual level of risk of three percent is not a low level of risk. According to Daniel Botkin, the risk of death arising from certain activities recognized as high risk are all well below three percent. For example, the risk of dying from smoking cigarettes or driving racing cars is less than 0.5% (1/2 of a percent). For this reason, I am not convinced that the risk of SOD spread via the nursery trade has been suppressed to the extent necessary to protect our native flora or the financial health of nurseries.

3) All inspection protocols should be based on sampling and testing of water, soil, growing media, pots, plants as well as plants (leaves, stems, roots). They should not rely only on visual inspection of plants.

The APHIS proposal continues to rely too much on visual inspection of plants for symptoms – despite decades of experience demonstrating the inadequacies of that approach. It is essential that surveys, inspections, compliance reviews, etc., rely on sampling and testing of water, soil, growing media, pots, etc.

4) Updates to the list of hosts should be Comprehensive

In the proposed regulation, APHIS states its intention to update the lists of hosts and “associated hosts”. However, the proposal does not include more than a dozen species growing in the wild or in gardens in the Pacific Northwest that scientists have identified as hosts of P. ramorum. These include several species of manzanita, Pacific dogwood, huckleberries, a Trillium, and the common garden groundcover Vinca.

A particularly puzzling gap is APHIS’ intention to name Japanese larch (Larix kaempferi) as only an “associated” host. It appears that APHIS has not accepted the peer-reviewed work of British scientists and the well-documented severe damage caused to this species in the United Kingdom.

Larch killed by P. ramorum in Wales; Wales Natural Resources

Less important, probably, but still annoying is APHIS’ failure to complete Koch’s postulates to clarify the host status of 89 species now listed as “associated hosts”. Since APHIS regulates “associated hosts” in the nursery trade in the same way as it regulates recognized hosts, the failure to act does not affect the regulatory regime. However, it does cause unnecessary confusion and undermines the scientific foundation of regulations.

Please Comment

I strongly suggest that readers submit comments on the proposed rule. At a minimum, ask that the new regulation incorporate the most current science regarding detection and management of Phytophthora ramorum. Simply codifying the years-oldFederal Orders without recognizing more recent information and developments would not serve anyone. I suggest objecting particularly to continued reliance on visual inspection of plants rather than the sampling and testing protocols developed through 20 years of experience in managing this difficult pathogen.

Posted by Faith Campbell

Update on Several Pests in Southern California

The native hardwood trees of southern California are under threat from several non-native insects and insect/pathogen complexes. I provided some recent information on one of these, the Kuroshio shot hole borer, in April; and a description of Californians’ efforts to counter the threat in August of last year. I think it is time to provide a more comprehensive update on the species.

Invasive Shot Hole Borers

I have blogged several times about the damage being caused to riparian trees in southern California by the polyphagous and Kuroshio shot hole borers – collectively referred to as the “invasive shot hole borers” or ISHB.

One of the most interesting sources of information about the shot hole borers are the series of visual surveys carried out by Orange County Parks under the leadership of Cathy Nowak (who has now retired). The most recent surveys were conducted in spring 2018 while deciduous trees were still dormant, so those estimates are based on the number of beetle gallery holes detected. An estimated 52,000 trees in the County’s parks are infested by either PSHB or KSHB. Eight regional parks and one historic house were surveyed. Only one large park remains uninfested. Comparing the results in 2018 to those of earlier surveys showed that percentages of host trees (in which the beetle can reproduce) that are infested rose over 2 years or less in seven of the parks – from a 9% increase in one park to a five-fold increase at another park with very low numbers of trees and low overall infestation rate earlier. The second highest increase is 89%.

The most heavily hit hosts are species long recognized as hosts See writeup on the borers here. Those with infestation rates exceeding 70% in one or more parks were

Acacia sp

Alnus rhobifolia (white alder)

Baccharis salicifolia (mule fat)

Erythrina caffra (coral tree)

Koelreuteria bipinnata (Chinese Flame tree*)

Koelreuteria paniculata (golden raintree)

Liquidambar styrachiflua (sweetgum)

Parkinsonia aculeate (palo verde)

Platanus occidentalis (American Sycamore)

Platanus racemose (California sycamore)

Platanus x hispanica (London plane)

Populus fremontii (Fremont cottonwood)

Populus trichocarpa (black cottonwood)

Quercus robur (English oak)

Salix spp. (willow)

* Chinese flame trees support ISHB only within cankered wood – other parts of the tree excrete thick gumming sap that protects.

Current information supports the vulnerability of California sycamore, and guidance that those seeking to learn whether the beetles have established should focus their surveys on sycamores.

As I have noted numerous times, several reproductive hosts are widespread in other parts of the country and could presumably support infestations there. These include box elder (not included in the Orange County surveys), sweetgum, and two magnolias – southern magnolia (M. grandiflora) and sweet bay (M. virginiana). Thirty-eight percent of the Magnolia grandiflora in one park were infested, although none was in three other parks. Koelreuteria spp. are a widely planted exotic across the country – although their role in spreading the disease appears to be limited by fact that they support ISHB development only in cankered wood. Birches have not been determined to be reproductive hosts, although one birch tree in one park had insect exit holes. Casuarina cunnninghamiana is also not known to be a reproductive host; trees in this genus are widespread invaders in Florida.

The good news is that none of a total of 12 southern live oaks (Quercus virginiana) growing in three parks had been attacked.

goldspotted oak borer

Goldspotted oak borer

The goldspotted oak borer attacks California black oak, coast live oak, and canyon live oak. It is now widespread and continuing to spread in San Diego County. Officials report that is now established in more than 10 parks in the County.

There is a heavy GSOB infestation in Idyllwild, on the eastern edge of Riverside County. This outbreak is clearly linked to importation of infested firewood. Due to the heavy 2017 fire season, planned removal of “amplifying” trees (heavily infested trees that support large numbers of reproducing beetles) did not occur – and the outbreak is growing. Trees in the San Bernardino National Forest are at risk; 13 were removed in 2017.

In Los Angeles County, so far only one site has been infested – Green Valley (which includes both private land and nearby portions of the Angeles National Forest). An estimated 50,000 oaks are in the area. Officials are removing the “amplifier” trees; they expect they might have to remove close to 3,000 trees at a cost of $6 million. Officials are also treating some trees.

A newly detected heavy infestation has been detected at campgrounds in the Trabuco Ranger District in the Cleveland National Forest. Forest Service officials are debating management options, with an eye to protecting as many coast live oaks as possible. They have had success in the past by treating some trees with chemicals.

Meanwhile, scientists will be trying to evaluate the effect of fire since the 2017 fires burned several infested areas, e.g., Weir Canyon in Orange County.

The principal management strategy is to identify and remove heavily infested “amplifier” trees. The wood and bark must be disposed of properly and quickly – if the wood is left on the ground over night, people take it – thereby spreading the insects. High-value trees that are not heavily infested can be protected by application of the topical contact insecticide Carbaryl on the lower trunk. Officials are also experimenting with oak restoration using either planting of acorns or promoting root sprouting of trees that have had to be cut down.

Thousand Cankers Disease

Thousand cankers disease of walnuts is very widespread throughout California, but it is not causing widespread rapid tree deaths. Juglans californica has multiple stems. If one is killed, the others usually survive. The impact on J. hindsii is greater because it has a single stem and is grown as a street tree. California officials last conducted a survey of walnuts in the state in 2015, at the height of the drought. They appear to be confident that the age of this survey has not affected their assessment of the risk.

Posted by Faith Campbell

In Absence of Federal Action, States take Initiative

As the federal government continues to dawdle in responding to invasive species challenges, some states are ramping up their efforts in significant ways.

California: New Legislation Creates a Program – but Only for One Year

The California state legislature has created a new invasive species program that focuses on those bioinvaders that threaten native ecosystems and the urban environment. It thus addresses some of the criticisms that I have previously levelled at the California Department of Food and Agriculture (CDFA) [see my earlier blogs here and here]

The new program has been established for one year; it will have to be renewed by the legislature next year.

The program results from adoption of legislation that combines what were initially two bills:

Assemblyman Timothy Grayson introduced AB 2470. This bill provided a legal foundation for the California Invasive Species Council and its Invasive Species Advisory Committee. It also provided funding for early detection and control projects targetting high-priority species, including weed management areas; and for supportive research and diagnostics work by the University of California.
Assemblywomen Lorena Gonzalez-Fletcher introduced AB 2054 focused specifically on the invasive shot hole borers [see descriptions of the polyphagous and Kuroshio shot hole borer here https://www.dontmovefirewood.org/ ]. The “Protect California Trees with Shot Hole Borer Beetle Prevention” (1) established a framework for a coordinated statewide effort; (2) instructed the Invasive Species Council of California and the California Invasive Species Advisory Committee to coordinate with state and local agencies and stakeholder groups to develop a plan to suppress the disease spread by this beetle.

The final legislation provided the full $5 million for addressing the shot hole borer but cut funding for the other components of the combined programs to just $2 million (so, a total of $7 million).

State officials have begun developing a shot hole borer management plan; they are expected to get input from a subcommittee by the Invasive Species Advisory Committee. The Advisory Committee held a meeting in mid-July to begin carrying out its coordinating functions.

Congratulations and thanks go to John Kabashima, who retired from his position as extension horticultural advisor with the University of California’s Division of Agriculture and Natural Resources. John has devoted two years to building the alliances needed to make this happen.

Minnesota: New Funding for Research

In 2014, the Minnesota legislature created the Minnesota Invasive Terrestrial Plants and Pests Center at the University of Minnesota. The Center applies science-based solutions to protect the state’s terrestrial ecosystems and agricultural resources. It utilizes an allocation from the Environment and Natural Resources Trust Fund to support a competitive research grant program. The current funding level is $3.5 million. Recently funded projects include evaluating the role of fungi in protecting ash trees from emerald ash borer and disease, genetic control of invasive insects, and use of goats in invasive plant control

The Center’s draft list of priority insects, plant pathogens, and invasive plants includes numerous forest pests. Among the 40 insect species listed, 19 are forest pests. Those in the top ten include mountain pine beetle, emerald ash borer, European and Asian gypsy moths, two elm beetles, and Asian longhorned beetle. Nineteen of 39 plant pathogens are tree-killers. Among the top ten are Dutch elm disease, oak wilt, Japanese oak wilt, Annosum root rot, sudden oak death, thousand cankers disease, and white pine blister rust.

In both cases, the lists include species that are already present and those not yet in the state (or even on the continent).

Western Governors’ Association: Initiative on Biosecurity

Incoming chairman, Hawaiian Gov. David Ige, has announced a Biosecurity and Invasive Species Initiative. The Initiative will focus on the impacts that invasive species have on ecosystems, forests, rangelands, watersheds, and infrastructure in the West, and examine the role that biosecurity plays in addressing these risks. Governor Ige hosted a webinar on 12 July [not yet posted on the WGA website] on which he was joined by such experts as Chuck Bargeron, Center for Invasive Species & Ecosystem Health, University of Georgia; Pam Fuller, Program Leader, Nonindigenous Aquatic Species Database, USGS; Stinger Guala, Director of Biodiversity Information Serving Our Nation (BISON), USGS; Jamie Reaser, Executive Director, National Invasive Species Council; and Lori Scott, Interim President & CEO, and Chief Information Officer, NatureServe. The Association is sponsoring regional workshops on various components of the invasive species response on the following dates

Lake Tahoe, NV Sept 17-18 – prevention, control, management of established species
Cheyenne, WY Oct 11 -12 – restoration
Helena, MT Nov 14 – early detection and rapid response
Hawai`i Dec 9 & 10 – biosecurity and agriculture

Posted by Faith Campbell

Study finds “targetted” phytosanitary measures are effective in reducing introductions of plant pests

Figure 2 from the article:

The number of new pathogens discovered each year on 131 focal host plant species in New Zealand (closed circles) and the mean annual rate of pathogen arrival estimated from the model (solid blue line), with shading showing the 95% credible interval.

Benjamin A. Sikes and several coauthors (article available here; open access!) find that targetted biosecurity programs can reduce the establishment of nonnative pathogens even while global trade and travel continue to increase.

The study relies on data from New Zealand because that country has more than 150 years of data on phytosanitary policies and pathogen introductions. Do other countries have data that would support a comparative study in order to test the authors’ conclusions more generally?

The study is unusual in analyzing introductions of a variety of forms of pathogens (fungi, oomycetes, and plasmodiophorids) rather than invertebrates. Pathogens pose significant plant health risks but are notoriously difficult to detect. The study used data on plant-pathogen associations recorded in New Zealand between 1847 and 2012. It focused on hosts in four primary production sectors: crops (46 species, including wheat, tomatoes, and onions); fruit trees (30 species, including grapes, apples, and kiwifruit); commercial forestry (42 species, including pines and eucalypts); and pastures (13 species of forage grasses and legumes). In total, 466 pathogen species for which the first New Zealand record was on one of these 131 host plants were included in the study. The pathogens were assumed to have arrived on imports seeds or fresh fruits of plants in the same family as the 131 hosts in the various production sectors.

After calculating each pathogen’s probable date of introduction, the authors compared those dates to contemporaneous levels of imports and incoming international travellers. Sikes et al. applied statistical techniques to adjust their data to the fact that detection of pathogens is particularly sensitive to variation in survey effort.

Findings:

The annual arrival rate of new fungal pathogens increased exponentially from 1880 to ~1980 in parallel with increasing import trade volumes. Subsequently rates stabilized despite continued rapid growth in not only imports but also in arrivals of international passengers.
However, there were significant differences among the four primary production sectors.

Arrival rates for pathogens associated with crops declined beginning in the 1970s but slightly earlier for those associated with pasture species. These declines occurred despite increasing import volumes.
Arrival rates of pathogens that attack forestry tree species continued to increase after 1960.
Arrival rates for pathogens that attack fruit tree species remained steady while import volumes rose steadily

Sikes et al. attribute these contrasting trends between production sectors to differences in New Zealand’s biosecurity efforts. They record when phytosanitary restrictions targetting the four sectors were adopted and link those changes to reductions in numbers of pathogens detected a decade or so later. They conclude that targetted biosecurity can slow pathogen arrival and establishment despite increasing trade and international movement of people.

Regarding the contrasting situation of the forestry and fruit tree sectors, Sikes et al. note that while phytosanitary inspections of timber imports was initiated in 1949, it focussed primarily on invertebrate pests. In addition, surveys for pathogens on fruit tree and forestry species were less robust than in the cases of crop and pasture species, and the peak survey effort occurred several decades later – in 1980 for fruit trees, 2000 for forestry species.

Furthermore, pathogens of forestry and fruit tree species can be introduced on types of imports other than seeds and fresh fruits, including soil and live plant material (e.g., rootstock) and untreated wood products.

Sikes et al. say there is no evidence of slowed pathogen arrival rates resulting from imposition of post-entry quarantine to live plant material beginning in the 1990s. I find this very troubling. Post-entry quarantine is a high-cost strategy. Still, several plant pathologists have advocated adoption of this strategy because they believed it would be sufficiently more effective in preventing introductions of – especially! – pathogens as to be worthwhile. Do others have data with which to add to our understanding of this disturbing phenomenon?

The authors suggest that introductions of tree-attacking pathogens on rising imports of wood packaging might have swamped decreases in introductions via other vectors. They consider that implementation of International Standard for Phytosanitary Measures (ISPM) No. 15 in 2002 means it is too early to see its impact in detection data. As I have blogged several times, implementation of ISPM#15 by the United States, at least, has reduced presence of detected pests – primarily insects – by 52%. Little is known about the presence of pathogens on wood packaging – according to some experts, inspectors rarely even look for pathogens. So I think the authors’ suggestion might not fully explain the continuing introduction of pathogens that attack tree species used in plantation forestry in New Zealand.

Prof. Michael Wingfield of South Africa has written numerous articles on the spread of pathogens that attack Eucalyptus on seeds imported to establish plantations in various countries; one such article is available here. This seems a more likely explanation to me.

The study’s analysis demonstrated that the overall rate of non-native fungal pathogen establishment in New Zealand was more strongly linked to changes in import trade volume than to changes in numbers of international passengers arriving on the islands. Although Sikes et al. don’t explicitly raise the question, they note that New Zealand has put considerable effort into screening incoming people – which appears from these data to have a smaller payoff than imposing phytosanitary controls on imports.

Recent declines in surveys mean the authors must estimate current pathogen arrival rates. The data gaps exacerbate the inevitable uncertainty associated with the time lag between when an introduction occurs and when it is detected. They estimate that an average of 5.9 new species of fungal pathogens per year have established on the focal host plant species since 2000. They estimate further that 55 species of pathogens are present in New Zealand but have not yet been detected there.

I am quite troubled by the reported decline in New Zealand’s postborder pathogen survey efforts since about 2000. This appears very unwise given that the risk of new introductions of pathogens that attack fruit and forestry trees continues – or even rises! Indeed, scientists associated with the forestry industry note the risk to Douglas-fir and Monterrey (Radiata) pine plantations from the pitch canker fungus Fusarium circinatum – which could be introduced on imported seeds, nursery stock, and even wood chips. Radiata pine makes up 92% of softwoods planted – and exotic softwoods constitute 97% of the plantation forestry industry.

Furthermore, non-native pathogens threaten New Zealand’s unique forest ecosystems. Since this study focused on non-native plant hosts, it does not address the risk to native forest species. However, the threat is real: Kauri trees – the dominant canopy species in some native forest types – is suffering from a dieback caused by an introduced Phythopthora. Also, two other pathogens threaten the many trees and shrubs in the Myrtaceae family found in New Zealand – Puccinia rust (which is established in Australia but not New Zealand) or the Ceratocystis fungi causing rapid ohia death – both threaten native forests in Hawai`i, as discussed in a recent blog.

Posted by Faith Campbell

Appropriations Update – Give A Big Round of Applause to the House Appropriations Committee

In mid-May, the House Committee on Appropriations adopted two bills crucial to funding efforts to counter tree-killing non-native insects and diseases. Please let them know you are grateful.

APHIS funding

The Agriculture appropriations bill funds APHIS (and other USDA agencies) for Fiscal Year 2019 (which begins on October 1). The new bill provides a total of $998,353,000 to APHIS, an increase of $16.4 million above the FY18 level and $259 million above the Administration’s request. ( I blogged about the Administration’s alarming request here.) You can find the bill here; the more informative report is posted here. Use search words to find specific APHIS programs.

The pest-related funding is apportioned among several areas:

Tree and Wood Pest Program. Unlike in previous years, the House bill does not cut funds for this program – which funds efforts to eradicate or contain the Asian longhorned beetle, emerald ash borer, and European gypsy moth. Instead, it maintains funding at the FY18 level of $54 million. Under the circumstances, this is good news. Thank you for your efforts to educate members of the House subcommittee on agricultural appropriations about this crucial program! (In past years, we relied on the Senate to restore funding for the Tree and Wood Pest Program.)

Specialty Crop Pests Program. The House increased funding by $10.8 million here, and specified that $15 million target the spotted lanternfly. This recently detected Asian leafhopper is spreading in southeastern Pennsylvania and was recently confirmed in Virginia’s Shenandoah Valley. It is a pest of native hardwood trees as well as of orchard and other crops.

Also, the Committee used its report to stress several concerns:

Access to emergency funding. In the report, the House Appropriations Committee reiterates its longstanding instruction that the USDA Secretary continue to use his authority to transfer funds from the Commodity Credit Corporation. They support using these funds – above and beyond appropriated funds – for the arrest and eradication of animal and plant pests and diseases that threaten American agriculture.

Brown Apple Moth vs. Emerald Ash Borer. Interestingly, the House Appropriations Committee encourages APHIS to engage state and international regulatory bodies as it moves to deregulate the light brown apple moth. The Committee expresses concern that if APHIS simply withdraws federal regulation without the necessary work with other officials, it will shift, not reduce, the regulatory burden. Then growers would carry the burden of preventing spread of the pest. I wish the Committee had made the same statement vis a vis the emerald ash borer! APHIS also plans to stop regulating this insect which continues to threaten still-uninvaded portions of the United States and Mexico.

Micornesia and Hawai’i. The Committee also instructs the Secretary of Agriculture to report to both the House and Senate Committees on Appropriations its progress implementing the Regional Biosecurity Plan for Micronesia and Hawai`i. This plan combines efforts by the U.S. Department of Defense, Department of the Navy, and the island governments to prevent transport of invasive species as a consequence of relocating military personnel from a base in Okinawa, Japan. More information is available here.

Forest Service funding

The Interior appropriations bill funds the US Forest Service (as well as Interior Department and Environmental Protection Agency).

Forest Health Management Program. The bill provides an increase of $19.5 million above FY18 levels for the forest health management program ($30 million above the Administration’s request). The Committee instructs the Forest Service to “work in concert with Federal agencies, States, and other entities to prioritize the allocation of these funds to address the greatest threats.” The emerald ash borer, “bark beetle” (which ones?) and cogon grass are expressly mentioned. The report is posted here. (It is unclear what actions the Forest Service is expected to take on the EAB, since regulations intended to curtail people from moving infested wood will soon be dropped by APHIS. The Forest Service could support breeding of ash trees resistant to the beetle.)

Forest Service Research. The Interior appropriations bill also maintained funding for Forest Service research at the FY18 level of $297 million – rather than cutting it to $259 million as advocated by the Administration. The Committee has called for the USFS to act within one year to “strengthen” its research program. The Committee expressly avoids endorsing several priorities advocated by Members of Congress while waiting for the Forest Service to implement this instruction.

If your representative is a member of the House Appropriations Committee (members listed here), please thank them for supporting APHIS’ and USFS’ programs. These funding increases shift several years of decline and are a true win for protecting our forests from non-native insects and pathogens!

Posted by Faith Campbell

Mixed News on Pest Dangers

‘ōhi‘a tree in flower

Worsening Threats to Hawaii’s Rich – and Rare — Native Forests

As I have written in previous blogs (October 2015; October 2016), the beautiful ‘ōhi‘a lehua (Metrosideros polymorpha) tree is ecologically and culturally the most important tree n the Hawaiian Islands. ‘Ōhi‘a trees dominate approximately 80% of Hawai`i’s remaining native forest. Loss of the species could result in significant changes to the structure, composition, and, potentially, the function, of forests on a landscape level. ‘Ōhi‘a forests are home to the Islands’ one native terrestrial mammal (Hawaiian hoary bat) as well as about 100 plant species listed as endangered by the U.S. Fish and Wildlife Service. Also 30 species of forest birds – in particular, the unique endemic honeycreeper subfamily — depend on ‘ōhi‘a. Eighteen of 19 extant Hawaiian honeycreepers in the main Hawaiian islands, including 12 of 13 bird species listed as endangered by the U.S. Fish and Wildlife Service, depend on ‘ōhi‘a for critical habitat.

Unfortunately, the threat to ‘ōhi‘a trees from three fungi appears to be rising.

“Rapid ‘ōhi‘a death” is caused by two fungi, Ceratocystis lukuohia and C. huliohia (formerly considered to be strains of Ceratocystis fimbriata). Rapid ‘ōhi‘a death has spread since 2010 to most districts of one island: Hawai`i or the “Big” Island. The total area affected is 135,000 acres. Still, most ʻōhiʻa forest on Hawai`i is still healthy, and the disease has not yet been found on any of the other islands. Scientists have begun exploring trees’ varying susceptibility and the possibility of breeding more resistant trees to be used for restoration. For more information, read the recently updated description here.

Ōhi‘a trees are also under attack by a third introduced fungus, called ‘ōhi‘a rust, guava rust, or myrtle rust. This is caused by Austropuccinia psidii (formerly named Puccinia psidii). Ōhi‘a rust has been established on all the Hawaiian islands since 2005. Until recently, it had caused little damage to ‘ōhi‘a – although it attacks several additional native plant species and has devastated the endangered endemic plant Eugenia koolauensis. This shrub can reproduce now only in nurseries where it can be treated for the fungus. In late 2017, an outbreak of the disease caused widespread defoliation and mortality of ‘ōhi‘a across hundreds of acres in at least four locations on windward portions of two islands, O‘ahu and Moloka‘i. It is not yet known whether this new damage resulted from introduction of a new, more virulent strain or from a period of unusually wet weather creating more favorable conditions for the fungus. For more information, read the recently updated description here. (Myrtle rust threatens plants in the Myrtaceae family across the Pacific; more than 450 species have been identified as hosts. Some species in Australia have been severely affected.)

laurel-wilt killed swamp bay in the Everglades

Severe Attacks on Redbay and other Laurels in the Southeast.

Since the turn of the century, redbay trees (Persea borbonia) in coastal regions of the Southeast have been dying because of laurel wilt disease. This is caused by the fungus Raffaelea lauricola, which in turn is vectored by the redbay ambrosia beetle (Xyleborus glabratus). Both the beetle and disease have spread rapidly since there were detected in 2002 near Savannah, Georgia. The disease now is found in eight states, reaching from eastern North Carolina south along most of the Florida peninsula; across the Gulf states with several locations in Alabama and Mississippi; and to isolated outbreaks in Louisiana and Texas. Already an estimated 320 million trees – nearly one-third of all redbays – have been killed. Mortality is highest where the disease first became established: Georgia (two-thirds of redbays killed), South Carolina (42% of redbays killed), and Florida (36% of redbays killed). In contrast, redbay mortality appears to be quite low in Alabama and Mississippi although mortality caused by disease might have been masked by application of fire or other silvicultural practices.

Other forest trees and shrubs in the Lauraceae family are also at risk. These include swamp bay (Persea palustris), which contribute greatly to the biological diversity of the “tree islands” scattered through the Everglades; sassafras (Sassafras albidum), which occupies a large range reaching into Michigan and southern New England; and two rare species – pondspice (Litsea aestivalis) and the federally listed pondberry (Lindera melissifolia). Northern spicebush (Lindera benzoin), another shrub in the Lauraceae family, does not attract the beetle so it is unlikely to sustain disease. In the West, California bay laurel has been determined by laboratory studies to be vulnerable.

Redbay is important to wildlife and has some use in horticulture. However, most attention has focused on the threat to avocados (Persea americana); the disease was detected in commercial orchards in 2012.

Concerned about loss of this ecologically important tree, scientists have begun efforts to breed redbays that are resistant to, or tolerant of, the disease. In addition to efforts by university scientists, the newly formed consortium Forest.Health (https://forest.health/) has listed redbay as a high priority for resistance breeding. For more information, read the updated description here.

initial damage caused by Kuroshio shot hole borer in Tijuana River Valley; I lack access to photos of recovery. Photo by John Boland

Hope in southern California – possible ecological limits to shot hole borer / fungal disease

John Boland, an ecologist who has studied southern California riparian wetlands for decades, reports that willows in the Tijuana River are recovering from attack by the Kuroshio shot hole borer and the fungi it vectors. After two years, the beetle-vectored disease had infested 88% of the willows in the valley (a total of 355,510 trees). An estimated 24% of the willows had been killed (95,791 trees). Nearly all of the infested and killed trees grew in the wettest parts of the riparian forests. (Photo above illustrates damage at this stage of the invasion.)

However, 71,280 of the willow trees have resprouted. By late 2017, these resprouts had created a new forest canopy that was about 5 meters tall. (Previously, the canopy had been about 20 meters tall). The median rate of infestation of these resprouting willows was 6% in 2017, down from 97% in 2015-2016. Some insect boring holes have healed.

In contrast, willows growing in drier parts of the valley were rarely attacked initially, but are now increasingly infested. In 2017, the median infestation rate was 78%, up from 9% in 2015-16. However, few trees have been killed.

Dr. Boland believes that the severity of the initial attack reflected the vulnerability of “soft trees”. Trees growing in the wetter parts of the Tijuana River Valley are inundated by sewage from the Mexican city. As a result of this artificial fertilization, they grow quickly and their wood is less dense.

For more information about the Kuroshio and phytophagous shot hole borers and their associated fungi, read the description here.. Dr. Boland’s study has been made available to participants in the southern California emerging forest pest groups but I cannot find a publicly available source on the Web.

Posted by Faith Campbell

APHIS Nursery Stock Regulations (Q-37) – Modernization Finally Completed!

citrus longhorned beetle – entered country several times in imported bonzai plants

After about 20 years, APHIS has finalized important changes to the regulations which govern imports of living plants (what they call “plants for planting”; the regulation is sometimes called “the Quarantine 37” rule). The new regulation takes effect on April, 18, 2018.

I congratulate APHIS on this important achievement!

[Twenty years is a long time – so changes happen. When APHIS released its Advance Notice of Proposed Rulemaking (ANPR) in December 2004 and its proposed rule in April 2013, I was employed by The Nature Conservancy and submitted comments for that organization. I will refer to those earlier comments in this blog. However, I now represent the Center for Invasive Species Prevention, so my comments here on the final regulations reflect the position of CISP, not the Conservancy.]

APHIS’ 2004 ANPR came after years of preparation. Then, more than eight years passed until the formal proposal was published on April 25, 2013. Comments were accepted from the public until January 30, 2014. During this nine-month period, 17 entities commented, including producers’ organizations, state departments of agriculture, a foreign phytosanitary agency (The Netherlands), private citizens, and The Nature Conservancy. [You can view the ANPR and proposal, comments on these documents, and APHIS’ response here — although you need to click on “Restructuring of Regulations on the Importation of Plants for Planting” and then “Open Docket Folder” to pursue the older documents.]

In the beginning, APHIS had a few goals it hoped to achieve: to allow the agency to respond more quickly to new pest threats, to apply practices that are more effective at detecting pests than visual inspection at points of import, and to shift much of the burden of preventing pest introductions from the importer and APHIS to the exporter.

Progress has been made toward some of these goals outside this rule-making. APHIS instituted a process to temporarily prohibit importation of plants deemed to pose an identifiable risk until a pest risk assessment has been completed (the NAPPRA process). APHIS has further enhanced its ability to act quickly when a pest risk is perceived by relying increasingly on “Federal Orders”.

At the same time, APHIS participated actively in efforts by international phytosanitary professionals to adopt new “standards.” These define a new approach to ensure that plants in international trade are (nearly) pest-free. Both the North American Plant Protection Organization’s regional standard (RSPM#24) and the International Plant Protection Organization’s global standard (ISPM#36) envision a system under which countries would no longer rely primarily on inspections at ports-of-entry. Instead, they would negotiate with the supplier or exporting country to develop programs to certify that growers’ pest management programs are effective. Both standards detailed: 1) how the place of production might manage pest risk and ensure traceability of plants; 2) how the importing and exporting countries might collaborate to administer the program; 3) how audits (including site visits) would ensure the program’s efficacy; and 4) what actions various parties might take in cases of noncompliance.

It was hoped that these international standards would lead to widespread adoption of “integrated pest management programs” composed of similar requirements – similar to the impact of ISPM#15 for wood packaging. However, living plants are more complex pest vectors than the wooden boards of crates and pallets, so each country was expected to negotiate its own specific programs – something not encouraged for wood packaging.

APHIS’ decades-long effort to amend its regulations is warranted because of the high risk of non-native insects and – especially – pathogens being introduced via international trade in living plants. U.S. examples include white pine blister rust, chestnut blight, dogwood anthracnose, and sudden oak death (all described briefly here )

dogwood anthracnose

According to Liebhold et al. 2012 (full reference at end of blog), 12% of incoming plant shipments in 2009 were infested by a quarantine pest. This is an approach rate that is 100 times greater than the 0.1% rate documented for wood packaging (Haack et al. 2014). I have discussed the living plant introductory pathway and efforts up to 2014 to get it under control in my report, Fading Forests III.

Shortcomings of the Final Q 37 Rule

So – how well does this final rule meet APHIS’ objectives?

First, will it shift much of the burden of preventing new pest introductions from the importer and APHIS to the exporter, while ensuring the system’s efficacy? In my view, on behalf of CISP, it falls short.

The new rule sets up a process under which APHIS might require that some types of imported plants be produced and shipped under specified conditions intended to reduce pest risk. However, non-American entities have little incentive to protect America’s natural and agricultural resources and from invasive species. So any new process needs severe penalties for violators.

We have seen how widespread and persistent compliance failures are for wood packaging under ISPM#15. http://nivemnic.us/wood-packaging-again-11-years-after-ispm15-problems-persist/ For this reason, I (on behalf of the Conservancy) had suggested that APHIS formally adopt a specific goal of “no new introductions”. I recognized that this goal was unachievable per se, but suggested that it should stand as a challenge and be the basis for adopting stringent restrictions on plant imports. I suggested limiting plant imports to those either a) produced under integrated pest management measures systems (verified by third-party certification) or b) plants brought into facilities operating under post-entry quarantine conditions — and following other best management practices that had been developed and supervised by independent, scientifically-based bodies.

In my current view, APHIS’ regulation falls far short of either this goal of shifting burdens or setting a truly stringent requirement. In fact, APHIS has explicitly backed away from its own original goals and procedures.

The new regulation does authorize APHIS to choose to set up import programs under which the exporting country agrees to produce plants for the U.S. market under a system of integrated pest risk management measures (IPRMM) approved by APHIS. In accordance with the international standards, the programs established under this new power will address how the place of production will manage pest risk and ensure traceability of plants; how APHIS and the exporting country will administer the program; how plant brokers will ensure plants remain pest-free while in their custody; how audits will be performed to ensure program efficacy; and what actions various parties will take in cases of noncompliance.

How efficacious this new approach will be in preventing new introductions will depend on how aggressive APHIS is in both choosing the plant taxa and places of-origin to be managed under such IPRMM programs and in negotiating the specific terms of the program with the exporting country.

It is discouraging that APHIS has ratcheted down how frequently it expects to rely on the IPRMM approach. In the explanatory material accompanying the final regulation, APHIS clarifies that did not intend that IPRMM would be used for all imports of living plants. The IPRMM framework is described as only one of several means to achieve the goal of preventing introduction of quarantine pests. APHIS will choose the “least restrictive measures” needed to prevent introduction of quarantine pests. To clarify its position, APHIS changed the introductory text to indicate that IPRMM will be applied when such measures are necessary to mitigate risk – that is, “when the pest risk associated with the importation of a type of plants for planting can only be addressed through use of integrated measures.” [Emphases added]

The final rule is also discouraging in some of its specifics.

Whereas the draft regulation specified steps that places of production must take to ensure traceability of the plants they produce, in the final regulation the traceability elements specified in each IPRMM agreement will depend on the nature of the quarantine pests to be managed. Again, APHIS seeks to ensure that its requirements are not unnecessarily restrictive.
Although the international standard had specified severe penalties when a grower or broker violated the terms of the IPRMM agreement, APHIS proposed to base the regulatory responses to program failures on existing bilateral agreements with the exporting country. Despite the Conservancy’s plea that APHIS follow ISPM#36 in adopting more specific and severe penalties, APHIS has not done so. The one bright spot is that APHIS may verify the efficacy of any remedial measures imposed by the phytosanitary agency of the exporting country to correct problems at the non-compliant place of production. [Emphasis added]
APHIS is relaxing the detailed requirements for state post-entry quarantine agreements – despite the Conservancy’s concern that such agreements’ provisions could be influenced by political pressure and other nonscientific factors.

Two Improvements

I am pleased that APHIS has retained requirements applied to plant brokers, despite one commenter’s objections. Brokers handling international shipments of plants grown under an IPRMM program must both handle the plants themselves in ways that prevent infestation during shipment and maintain the integrity of documentation certifying the origin of the plants. A weakness, in my current view, is that APHIS will allow brokers to mix consignments of plants from more than one producer operating under the IPRMM program. APHIS does warn that if non-compliant (infested) plants are detected at import, all the producers whose plants were in the shipment would be subject to destruction, treatment, or re-export.

A major improvement under the new regulation is that APHIS will now operate under streamlined procedures when it wishes to amend the requirements for importing particular plants (whether a taxon, a “type”, or a country of origin). Until now, APHIS has been able to make such changes only through the cumbersome rulemaking process, Instead, APHIS will now issue a public notice, accept public comments, and then specify the new requirements through amendment of the “Plants for Planting Manual” [ https://www.aphis.usda.gov/import_export/plants/Manuals/ports/downloads/plants_for_planting.pdf ] APHIS estimates that such changes can be finalized four months faster under the new procedure.

A Final Caveat

Finally, APHIS needs to be able to measure what effect the new procedures have on preventing pest introductions. Such measurement depends on a statistically sound monitoring scheme. APHIS has stated in some documents that the current Agriculture Quarantine Inspection Monitoring (AQIM) system doesn’t serve this purpose. APHIS needs to develop a valid monitoring program.

References

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

Liebhold, A.M., E.G. Brockerhoff, L.J. Garrett, J.L. Parke, and K.O. Britton. 2012. Live Plant Imports: the Major Pathway for Forest Insect and Pathogen Invasions of the US. www.frontiersinecology.org

Posted by Faith Campbell

Action on the Threat from Phytophthoras in Restoration Plantings

In July 2016 I blogged about the risk that native plant nurseries in California might spread various Phytophthoras to natural areas through use of infected plants used in restoration plantings.

In response to this threat, the California Oak Mortality Task Force has formed a Phytophthoras in Native Habitats Work Group to protect wildlands and assist the restoration industry in adopting practices to ensure they are producing “clean” plants.

The California Native Plant society (CNPS) adopted a policy to promote propagation practices that help prevent plant diseases. CNPS also established its own Ad Hoc Committee on Phytophthoras to address the same threat.

Numerous resources, including guidelines for nursery management, restoration plantings, summaries of committee meetings, photographs, etc., are posted at this website.

As I described in the July 2016 blog, Phytophthora pathogens have been detected in nurseries in other states, including Maryland, Minnesota, North Carolina, Oregon, and Tennessee. Doubtless nurseries in additional states also harbor damaging pathogens.

I’m not aware of action by regulatory officials, nursery owners, or conservation practitioners in these other states to evaluate and address this threat? Are you?

Posted by Faith Campbell