About the Lab
The Plant Industry Bureau Laboratory provides plant pest and disease diagnostic services to the bureau's programs and conducts early detection surveys for diseases of economic and regulatory significance. Plant samples with diseases caused by bacteria, fungi, nematodes, and viruses are submitted to the lab by DATCP inspectors and survey specialists trained to recognize disease symptoms. The lab uses microscopy, culturing, enzyme-linked immunosorbent assay (ELISA), polymerase chain reaction (PCR), recombinase polymerase amplification (RPA) and sequencing to identify pests and pathogens.
In 2024, the lab processed 679 plant samples for diseases and 46 plant samples for insect and mite concerns in support of DATCP's statewide surveys and regulatory inspections. In addition, 1,101 insect trap samples were screened for regulated and non-native pests. The lab conducted a total of 2,040 tests on the 679 plant samples processed for disease identification.
The PIB Lab participates in the USDA-APHIS-PPQ Science and Technology’s Plant Pathogen Diagnostics Certification Program which provides proficiency certification to participating labs for the lab techniques real-time PCR, conventional PCR, ELISA, manual DNA extraction, and semi-automated DNA extraction, as well as for pathogen-specific results interpretation. In 2024, the PIB Lab had two diagnosticians certified for real-time PCR, manual DNA extraction, and Phytophthora ramorum real-time PCR assay interpretation. Participation in this program is a requirement for testing PPQ regulated samples such as Phytophthora ramorum suspect samples.
As a member laboratory in the National Plant Diagnostic Network (NPDN), the Plant Industry Bureau Laboratory represents Wisconsin as part of an extensive diagnostics system of labs throughout the United States. The NPDN system of more than 70 labs protects national plant health by providing accurate, rapid pest and disease identification and reporting.
Current Topics
In addition to providing diagnostic services, the lab carries out surveys targeted at specific exotic pathogens and nematodes identified as national or state priority plant pests of concern. Below are the summaries of recent survey projects.
New State Records
Cycas necrotic stunt virus
Lab testing conducted at the University of Minnesota confirmed a new Wisconsin state detection for the pathogen cycas necrotic stunt virus in 2024. This virus was found during a routine nursery inspection in Manitowoc County on two types of peonies. The PIB Lab will monitor for CNSV on Peony nursery stock in 2025.
Elm Zigzag Sawfly
DATCP's Forest Entomologist detected the invasive elm zigzag sawfly in July of 2024 on both American and Chinese elms in central Wisconsin. The PIB Lab confirmed this new Wisconsin state detection, identifying all life stages of this pest. Subsequent detections of the elm zigzag sawfly were made in 20 additional counties throughout the state in the months following this first detection. DATCP encourages people to report sightings of this pest to either iNaturalist or EDDMapS. For information on this pest, including identification and management, visit:
https://hort.extension.wisc.edu/articles/elm-zigzag-sawfly.
Community Garden Solanaceous Virus Survey
In 2024, DATCP plant pathologists conducted a survey of five Milwaukee County community gardens for tomato brown rugose fruit virus (ToBRFV) and potato spindle tuber viroid (PSTVd). Fifty potato, pepper, and tomato leaf samples were collected across the five gardens. Samples were tested at the DATCP PIB Lab and there were no detections of ToBRFV or PSTVd.
Learn more about the
Community Garden Solanaceous Virus Survey.
Wheat Blast Survey
Surveys in wheat fields across the southern and east-central areas of the state in June 2024 found a high incidence of disease symptoms due to wet spring conditions. DATCP specialists sampled 61 fields June 6-21 in the following counties: Brown, Calumet, Columbia, Dane, Dodge, Door, Fond du Lac, Kewaunee, Manitowoc, Sheboygan, and Winnebago. These 11 counties contain the majority of the wheat acreage in the state. In each field, a sample consisting of 20 wheat heads and leaves was collected for testing at the DATCP Plant Industry Bureau Lab. Fungal diseases were common in the surveyed fields, particularly Fusarium head blight which was found in nearly half of the sites checked (27 fields). Other diseases detected on the wheat samples included Alternaria head mold (seven fields) and rust (10 fields).
All samples tested negative for the wheat blast pathogen Magnaporthe oryzae Triticum pathotype, a national priority pest predicted to spread through wheat-growing regions of the world under climate change conditions. Wheat blast was first reported in Brazil and has led to locally severe epidemics with up to 100% crop loss in fields in South America (Argentina, Bolivia, Brazil, Paraguay), Africa, and Asia. DATCP targeted wheat blast as part of a USDA APHIS cooperative agreement. To date, this aggressive fungal disease has never been found in Wisconsin.
Viruses of Nursery Ornamentals
Inspectors collected 145 ornamental samples for virus testing at the lab. Tobacco rattle virus (TRV) was detected most often, with 44 positives (mainly in anemone, astilbe, bleeding heart, and hosta). Tobacco streak virus (TSV), confirmed on 22 astilbes, was the second most detected virus. Hosta virus X (HVX) was diagnosed in 11 hosta samples. In addition, potyviruses were confirmed on two gladiolus, two hosta, one lungwort, two phlox, and one sedum, for a total of eight detections.
Other virus finds included cucumber mosaic virus on one bleeding heart and one monkshood, cycas necrotic stunt virus on two peonies, dahlia mosaic virus on one dahlia, an unidentified Ilarvirus on one anemone, tobacco ringspot virus on one geranium, and tomato spotted wilt virus on one impatiens, one iris, and one globeflower. Laboratory test results are summarized in the
PIB Annual Report.
Learn more about the symptoms plant viruses cause on ornamental plants in our
Gallery of Ornamental Plant Virus Symptoms.
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Status Reports
- Soybean Cyst Nematode in Wisconsin
- Crop Export Certification Testing
Soybean Cyst Nematode Status Report
Since soybean cyst nematode's (SCN) first detection in the state in 1981, DATCP has maintained a record of new county level detections. In 2023, Barron County had its first detection of SCN, making it the 54th County in Wisconsin with a detection.
Learn more about SCN and its statewide distribution in the
Soybean Cyst Nematode Status Report.
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Crop Export Certification Testing
Exports of agricultural, fruit, ornamental and vegetable crops grown for seed or plants-for-planting are inspected during the growing season for regulated plant pests. This year, 80 seed fields totaling 305 acres were inspected for 16 seed companies and growers, and 102 samples were sent to DATCP's Plant Industry Bureau Lab for testing. A total of 470 tests for 145 different plant pathogenic bacteria, fungi, viruses, and nematodes were performed on the samples. The regulated pathogens detected in 2024 during seed field inspection testing include
Alternaria porri (purple blotch, 1),
Cercospora zea-maydis (gray leaf spot, 1),
Colletotrichum graminicola (anthracnose, 1), High Plains virus (1),
Setosphaeria turcica (northern corn leaf blight, 6), and Sugar cane mosaic virus (2) which are all known to occur in Wisconsin.
Learn more about the PIB Lab's
Crop Export Certification Testing.
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