| Section five: plant health |
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| Introduction |
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Plant health section staff
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The Plant Health Section provides official field inspections and laboratory testing for Oregon’s seed, nursery, and Christmas tree industries. For other commodities, such as cherry and onion, we conduct surveys to establish pest-free status for specific counties. These inspections, surveys, and tests are required for shipment to interstate and international markets. The section’s pathologists also provide commodity groups and trade negotiation officials with official statements to facilitate the opening of new markets for Oregon’s agricultural commodities.
The Plant Health Section has responsibility for several state quarantines, control area orders, and other regulations for plant pathogens. These administrative rules are designed to prevent exotic pathogens from being introduced or becoming established in the state and to provide quarantine pest-free production areas for Oregon growers.
In cooperation with USDA, the Plant Health Section conducts statewide surveys for exotic pathogens. These surveys are federally funded and help provide crucial data to keep interstate and international markets open to Oregon’s agricultural products.
We are also active in helping to shape national policy on important pathogens such as Phytophthora ramorum and potato cyst nematode. Staff scientists are regularly consulted by PPQ, and provide crucial input to national plant disease control efforts. Staff expertise is maintained and enhanced with a research program that develops and publishes new diagnostic protocols for regulated and emerging plant pathogens.
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| Highlights |
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In 2006, P. ramorum was detected in 13 nursery and related sites. At one nursery, both the growing grounds and retail area were infected. Quick responses by the Plant Health and Nursery & Christmas Tree sections allowed for the eradication of P. ramorum from these sites. Eradication efforts in Curry County continue.
Surveys were completed for onion smut in Morrow and Umatilla counties and for plum pox virus in Willamette Valley nurseries and orchards. Neither pest was found. These surveys were done to meet international and federal regulatory requirements for shipments.
The total number of vegetable seed fields inspected for pathogens of regulatory concern rose 11 percent from last year. The total acreage inspected also increased 15 percent.
The Plant Health Program worked closely with Commodity Inspection Division, the Oregon State University Seed Certification Service, and the Oregon Potato Commission to develop a coordinated response to the USDA State/National Harmonization Plan for seed potatoes. A quality manual for participation in the plan was developed and submitted to USDA for approval.
For the second year in a row, the Plant Health Section was at full staff. Erika Berghauer (NRS 1) left the program for a research position in her native Wisconsin. Moriah LaChapell-Schalock was hired to fill her position.
With this dramatically increased workload, the staff managed to sustain the high level of competence expected of our Section, maintaining a low laboratory test error rate of 0.3 percent. It is a privilege to serve with such an exceptional and dedicated group. Thank you for all your hard work.
Nancy K. Osterbauer, Ph.D.
Plant Health Program Manager
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| Eradication programs |
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Phytophthora ramorum
Phytophthora ramorum, the cause of sudden oak death (SOD) and related diseases, was first discovered in Curry County, Oregon in 2001. Since then, the ODA, Oregon Department of Forestry (ODF), USDA Forest Service, Oregon State University, and the affected landowners have been trying to eradicate the pathogen from the infected forest areas. Since 2001, a total of 128 acres have been treated for the disease. Treatment consists of cutting, piling, and burning host plants within each infection center and asymptomatic hosts within 100- to 300-feet of each infection center. Tan oak stumps are treated to prevent re-sprouting. The sites have been monitored periodically since being treated. Surveys in and around the sites showed that the treatments effectively limited the spread of the pathogen on most sites despite highly favorable environmental conditions for disease development and spread. Of the 691 samples collected within the sites in 2006, three soil samples and nine plant samples were positive for the pathogen post-treatment. The eradication and monitoring efforts will continue in 2007.
In 2006, aerial, ground, and stream surveys for P. ramorum were conducted in southwestern Oregon. The ODF led this effort with cooperation from the other agencies. The aerial survey covered 577,876 acres. All dead tan oaks identified from the air were then checked on the ground. Ground checking of suspicious trees identified another 40 acres (including expansions of previously identified sites) that required treatment for P. ramorum. Two new sites were detected outside of the existing quarantine area. Stream surveys were conducted on waterways within and outside of the quarantine area. Two stream positives were found outside the quarantine area. Intensive monitoring of the surrounding flora has detected no P. ramorum. Three stream positives found within the quarantine area identified new infection centers that required treatment. These findings will lead to an expansion of the quarantine area in 2007. All positive sites will be treated as described above. Because of weather-related delays and limited resources, the treatment of these infected acres will carry over into 2007. The sites will be monitored for the pathogen for at least two years post-treatment. If P. ramorum is not detected during that time, the pathogen will be declared eradicated.
On December 21, 2004, the USDA adopted a federal order requiring that all West Coast nurseries shipping plants interstate be surveyed for P. ramorum. As in 2005, nurseries growing P. ramorum-susceptible plants (host nurseries) had to be visually surveyed for suspicious symptoms and a specific number of samples collected for laboratory testing using USDA-approved methods. Nurseries growing non-susceptible plants had to be visually surveyed for suspicious symptoms as well. Nurseries found to be P. ramorum-free entered into federal compliance agreements in order to ship interstate (see related article in the nursery & Christmas tree section).
ODA staff collected 79,930 samples from 1,362 host and 32 non-host nursery growing areas to test for the presence of P. ramorum using the USDA-approved ELISA, nested PCR, and qPCR tests. The USDA requires that all first-time nested PCR- or qPCR-positive samples from a growing area be sent to their laboratory for official confirmation. Phytophthora species were detected at 211 (15 percent) and P. ramorum at 13 (<1 percent) of the sites surveyed. The USDA Confirmed Nursery Protocol was enacted at the 13 sites. All 13 have completed the protocol. Eight hundred host nurseries and 993 non-host nurseries have entered into federal compliance agreements and are eligible to ship plants interstate.
In May 2006, the ODA surveyed Christmas tree plantations planted in Abies spp. and Pseudotsuga menziesii for P. ramorum. Plantations in 21 counties were surveyed. The number of plantations surveyed in each county varied depending upon the total acreage of Christmas trees grown within the county. A total of 117 plantations were visually inspected according to the standards of the 2006 USDA National Survey Protocol for P. ramorum, with 4,630 samples collected for testing as described above. P. ramorum was not detected in any of the samples, although another Phytophthora was detected at two of the plantations. This is the fifth consecutive year that no P. ramorum has been found in Oregon Christmas tree plantations.
Throughout the state, ODA surveyed retail nurseries that sell plants susceptible to P. ramorum. One hundred twenty-six retail nurseries were visually inspected according to the standards of the 2006 USDA National Survey Protocol, with 5,170 samples collected for testing as described above. Phytophthora species were detected at 16 (13 percent) and P. ramorum at one (<1 percent) of the sites surveyed. The single positive retail nursery was the retail outlet of a positive grower nursery. The USDA Confirmed Nursery Protocol was enacted and completed at the site.
In addition to the agricultural commodities surveys described above, the ODA has completed trace-out investigations to both nursery and landscape sites. One hundred twenty-six sites have been surveyed with 3,323 samples collected for testing as described above. Phytophthora species have been detected at eight sites (6 percent). No P. ramorum has been detected at the sites.
Based on the nursery surveys and trace out investigations described above, a total of 13 nursery sites were infected with P. ramorum in 2006. At one site, both the grower and retail areas were infected. The appropriate USDA eradication protocol was enacted at each site. ODA staff collected and tested a total of 37,363 samples to meet the requirements of the USDA Confirmed Nursery Protocol.
ODA staff also surveyed 27 shipments of nursery stock for P. ramorum, collecting 720 samples for laboratory testing. No P. ramorum was detected although another Phytophthora was detected in three of the shipments. The ODA also conducted enhanced perimeter (forest) surveys around the 13 infected nursery and landscape sites according to the USDA Forest Service National Survey Protocol. Of the 54 samples collected for testing, none were infected with P. ramorum.
Survey results were posted in the National Agricultural Pest Information System (NAPIS).
Chart: the number of agricultural commodities samples collected and tested for P. ramorum since 2001
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| Certification and survey programs |
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Columbia root-knot nematode
Nursery Program staff collected 122 nematode soil and root samples from Oregon production nurseries in 2006. Plant-parasitic nematodes were detected in 62 percent of the samples with Pratylenchus spp. being the most abundant (present in 46 percent of the samples). Meloidogyne species were detected in five samples. No Columbia root-knot nematodes (M. chitwoodii, CRKN) were detected in Oregon nurseries based on morphometric analysis of juveniles. This annual survey is conducted at the request of Canadian agricultural officials to demonstrate that Oregon production nurseries are free of CRKN.
Potato cyst nematode survey
Staff members collected 92 field soil samples from Oregon potato fields for Globodera pallida (potato cyst nematode, PCN) and G. rostochiensis (golden nematode). The samples were collected and processed following the USDA National Potato Cyst Nematode Survey Plan. The plan was developed by USDA-APHIS-PPQ after potato cyst nematodes were found in Idaho in April 2006. This was the first time PCN has been detected in the United States. The survey plan is targeted acreage planted with potatoes in 2006. ODA plans on collecting 1,700 more soil samples in 2007. Even though the survey will be completed in 2007, all samples collected must be from the 2006 potato fields. All seed potato fields will be tested and 10 percent of commercial potato fields. Ten percent of the fields will be sampled using a 4 x 4 grid at the headlands of the fields. To date, no potato cyst nematodes have been found.
Allium white rot
In 2006, the ODA adopted rules for white rot certification of vegetative Allium seed to replace the control area order (CAO) for central Oregon. The CAO, which included quarantine language, was repealed because the disease is established in central Oregon and the certification program adopted because a vegetative Allium seed industry still exists in that part of the state. The Plant Health staff inspected 35 fields (1,493 acres) of garlic for the presence of white rot, Sclerotium cepivorum, in central and eastern Oregon in 2006. The inspection is a 100 percent visual inspection, designed to find single strikes of white rot. Three fields bordering each other were found with white rot.
Mint Verticillium wilt
The Plant Division offers a mint rootstock field inspection service to detect Verticillium species in established control areas. Under the provisions of the control area order, any fields confirmed as V. dahliae-positive cannot be used as a rootstock source. Mint growers in Union County submitted requests to inspect 15 fields. Growers in Klamath County submitted requests to inspect three fields. The total acreage inspected was 352. Verticillium species was detected in four fields in 2006.
Potato late blight
Staff from ODA’s Commodity Inspection and Plant divisions conducted field surveys for potato late blight caused by the fungus Phytophthora infestans in northeast, south-central, western, and northwest Oregon. A total of 104 fields and 7,658 acres were inspected in 2006. Ten varieties were inspected with Russet Norkotah the most common. No potato late blight was found. This survey is done to meet the import requirements of Taiwan.
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| Seed field disease inspections |
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Staff from Plant Health inspected 518 seed fields (10,632 acres) for the presence of seed-borne or seed-associated pathogens of regulatory concern in 2006. This represents a 11 percent increase in the number of seed fields surveyed from the previous year. Inspectors looked for the presence of 100 different pathogens in 29 different seed crops. Surveys found 129 seed fields with at least one disease of concern. The majority of fields (75 percent) were free from disease. The most common pathogens observed were Xanthomonas campestris pv. carotae causing bacterial blight of carrot, Erwinia carotovora subsp. carotovora causing soft rot of carrot, Botrytis porri causing neck rot of onion and garlic, Sclerotinia sclerotiorum causing stem rot of cabbage, and Ustilago maydis causing common smut of corn.
Chart: Overview of seed fields grown for export inspected for diseases of regulatory concern (1992-2006)
Cherry leaf spot survey
In June 2000, sweet cherry growers in the Pacific Northwest were granted access to the Australian market. A key step in obtaining access was the acceptance of general surveillance data documenting the absence of cherry leaf spot (CLS, Blumeriella jaapii) in virtually all cherry producing counties in the region. The exception was Hood River County where, in the mid 1980s, CLS was unofficially reported to be the cause of leaf damage. Since that first unofficial report, grower and other surveys suggested that CLS in not present in the area. In order to open the market, an official survey for CLS that met Australian phytosanitary standards was conducted in Hood River and Wasco counties.
Based on Australia’s CLS survey protocol, ODA surveyed cherry trees between five and 40 years of age. Isolated orchards were included in the survey to cover the broadest area possible. Orchards were inspected in May, after the trees were in full leaf. Ten percent of all orchards in each county were surveyed and 20 to 25 percent of trees in a selected orchard visually inspected for B. jaapii. In Hood River County, 18 orchards (324 acres) were selected and 100 acres (31 percent) were inspected. In Wasco County, 18 orchards (2,976 acres) were selected and 632 acres (21 percent) were inspected. Each selected orchard was inspected row by row until at least 20 percent of the orchard had been inspected. Cherry leaves were visually inspected for any leaf spot symptoms. Symptomatic leaves were sampled and taken to the Oregon State University Extension Service—Hood River or the ODA Plant Health Laboratory for further examination. All samples were free of B. jaapii. Based on this official survey, the cherry orchards in Hood River and Wasco counties are free of CLS.
Onion smut survey
In July 2006, 12 onion fields in Morrow and Umatilla counties (734 acres representing 14 percent of the planted acreage) were surveyed for onion smut caused by Urocystis cepulae. No onion smut was identified in these fields. This is the third annual survey (2004-2006) requested for fresh onion export to Australia. The survey results were uploaded in the National Agricultural Pest Information System (NAPIS) to meet the quarantine requirements of Australia.
Karnal bunt
Karnal bunt, Tilletia indica, is a fungal disease of wheat. After its discovery in Arizona, many countries implemented quarantines to prevent the introduction of this disease. In response to those quarantines, Oregon began participating in a national survey program that certifies wheat as free from Karnal bunt. Oregon has participated in this program since 1996 and has never found Karnal bunt. In 2006, 36 samples were obtained from 12 counties that produced commercial quantities of wheat and were sent to the federal testing laboratory in Texas for processing. Karnal bunt spores were not found in any of the wheat samples examined. Results were entered in the NAPIS database.
Virus certification of nursery stock
Twenty-three nurseries participated in the fruit and ornamental tree virus certification program in 2006. Malus spp., Prunus spp., Pyrus spp. and Cydonia spp. are included in the testing program. This year, 3,224 individual Prunus mother (scion) trees and 8,543 Malus spp., Pyrus spp., and Cydonia spp. individual trees (up 2 percent from last year) were tested for tomato ring spot virus, prune dwarf virus (PDV), and Prunus necrotic ring spot virus (PNRSV) using ELISA. PDV was detected in 101 trees (3 percent infection rate) and PNRSV in 51 trees (<2 percent infection rate). A summary of the virus-free varieties grown by each nursery is sent yearly to state, federal, and Canadian officials to facilitate the movement of the nurseries’ products.
Apple chlorotic leaf spot virus (ACLSV) testing was added in 2004 because of a new quarantine requirement imposed by the Washington State Department of Agriculture (WSDA) and to comply with Canadian and Mexican regulations for the import of plant material from the USA. This testing is conducted in the fall because the virus is present at higher levels in dormant buds. In 2006, we collected and tested 1,755 field samples of Malus and Pyrus rootstock and stool bed materials using diagnostic techniques and sampling procedures required by WSDA. Eighty-six samples were positive for ACLSV (about 4 percent infection). To determine the presence of ACLSV in other fruit and ornamental tree (including Prunus sp.) scion wood, more than 200 field samples were collected and tested from nurseries participating in the virus certification program. Two positive samples of one Pyrus cultivar were infected (1 percent infection).
Blueberry virus testing
Seven nurseries participated in the testing program for blueberry scorch Carlavirus (BlScV) and blueberry shock Ilarvirus (BlShV) in 2006. The testing is done at the request of nurseries to comply with the regulatory requirements of other states and countries. A different sample collection protocol was used this year. A total of 10,545 samples were collected by nursery inspectors and submitted to the laboratory for testing. BlShV was detected in 475 field samples from one nursery using ELISA. No BlScV was detected. Potato virus Y
The USDA Animal & Plant Health Inspection Service (APHIS) and the Canadian Food Inspection Agency entered into an agreement to survey all potato-growing states for Potato Virus Y (PVY) and its variant PVYN (necrotic strain). The USDA is requiring random testing of field-grown potatoes from lots fourth generation or higher. The department, with the help of the Oregon State University Seed Certification Program, identified and tested 1,122 tubers collected in 2006. Another 604 tubers from Washington were also tested. PVY complex was detected in 4 percent of all tubers tested. The ODA anticipates testing about 1,500 tubers from both states in 2007, the final year of the survey.
Plum pox virus
The aphid-transmitted plum pox virus (PPV) is a quarantine pathogen within the USA, Canada, and other countries. In 2000, this virus was first reported in Pennsylvania and Canada where eradication programs are underway. In 2006, new PPV detections were reported in New York and Michigan. In order to maintain our free-from status for this pathogen and to meet the import requirements of our customers, Oregon must survey regularly for this virus. Our last survey was conducted in 2002. This year, 1,813 field samples were collected from nurseries and from cherry orchards and then delivered to the Plant Health Laboratory for testing using APHIS-approved protocols. All samples tested were free of PPV infection.
Laboratory grass seed testing
In 2006, Plant Health staff conducted about 7,000 laboratory tests to detect specific seed-borne fungi, bacteria, nematodes, viruses, pests, diseases, and other miscellaneous problems. A total of 4,169 seed lots of more than 15 different crops were tested. There were 3,669 tests conducted for pest and disease plus soil and an approximately equivalent number of other miscellaneous diagnostic tests conducted. A total of 393 seed lots out of 4,169 (9 percent) tested were positive according to approved testing protocols for one or more pathogens of regulatory concern. These tests were requested by Oregon seed producers to meet the phytosanitary requirements of their foreign customers.
Chart: Percent of different tests performed
Endophyte testing
In 2006, the Plant Health Laboratory received 197 seed lots of forage grass seed varieties (up 10 percent from last year) to be tested for the presence of the endophyte fungus, Epichloe sp. The endophyte fungus produces alkaloids that can be toxic to livestock. To qualify for an endophyte tag, no more than 5 percent of the seeds in a lot can be infected. Twenty-six (26) seed lots out of 197 tested positive, with more than 5 percent of seeds infected.
Dutch elm disease
Dutch elm disease, a deadly tree disease caused by the fungi Ophiostoma novo-ulmi and O. ulmi, is present in Oregon’s Willamette Valley. It was first detected in 1978 in Portland. Its normally rapid spread has been slowed by a diligent survey and eradication program supported by a state quarantine. In 2006, 27 samples were submitted to the laboratory with DED detected in 20 of those samples. The majority of infected samples were from the Portland area. For the first time, DED was detected in southern Oregon in the city of Medford.
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| General diagnostic tests |
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The Plant Health Laboratory provides a general diagnostic service for the nursery industry, various governmental agencies, licensed landscapers, and other customers. Many tests are conducted in addition to those required by specific survey and certification programs. The laboratory activities related to certification programs are summarized elsewhere.
This year the Plant Health Laboratory performed 226 general diagnostic and nursery tests. Tests performed included screening for nematodes (mist chamber and sucrose filtration), fungi and bacteria (microscope and media), and visual analysis for pests and abiotic problems. Plant pathogens were found associated with 65 percent of the samples tested. Nematodes (35 percent) and fungi (21 percent) were recovered the most often. Other plant pathogens recorded included bacteria (3 percent) and viruses (less than 1 percent). No phytoplasmas or parasitic plants were detected in the samples for 2006. Of the other plant disorders, abiotic symptoms comprised 6 percent, while insects accounted for 1 percent. No cause for disease was determined on 11 percent of the samples.
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| Quarantines and control area orders |
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Staff reviewed Plant Health Section quarantines and control area orders (CAO) to determine if the rules needed to be updated or repealed. This is an annual review process. In 2006, the Peach Latent Mosaic Viroid, Phytophthora ramorum, and Peach Yellows Phytoplasma quarantines were updated to reflect new information about the pathogens and their known distribution. Minor editing was done to the CAO for Yellow Dwarf in Yamhill and Washington Counties and the Bean Disease CAO for Malheur County. The P. ramorum Regulated Area for Nursery Stock was updated to reflect changes in the federal regulations for this pathogen. The Blueberry Nursery Stock CAO was revised to include cost recovery for our official testing program. The laboratory fees for official, regulatory, and service samples were updated to include fees for new testing services offered.
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| Permits for genetically modified organisms |
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ODA does not have specific regulations for transgenic organisms, but we cooperate with USDA in their permit process. In 2006, 25 notifications and permits for transgenic plants were reviewed by ODA, down by 20 percent from last year. Eight different crops were modified for a wide variety of traits (see table). The notifications and permits were reviewed to ensure that the transport and/or growth of the transgenic organisms would not violate any existing state quarantines and control area orders, and would not pose a significant risk to Oregon agriculture. Along with USDA officials, ODA representatives also inspected the research sites of several transgenic permit and/or notification holders.
Crop species genetically modified, number of applications, and traits added in 2006
| Crop/Other | No. of applications
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| | Aspen | 4 | AP, PQ | | Canola | 2 | HR,AP,PQ,HT | | Corn | 9 | IR,AP,HR,FR,MG,OO,PQ | | Poplar | 2 | OO,AP | | Potato | 2 | IR,PQ,AP,FR
| | Soybean | 1 | MG,HT,AP,OO,PQ,FR,IR,HR,NR | | Sweetgum | 1 | OO | | Tomato | 4 | FR |
*HR = herbicide resistant, IR = insect resistant, AP = agronomic properties, FR = fungus resistant, MG = marker gene, OO = other, PQ = product quality, HT = heat tolerant, NR = nematode resistant, and BR = bacteria resistant.
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