Services

Soil Fungi Assays

Prices listed are per soil sample. Please allow approximately 2-4 weeks for Pythium, Fusarium, and Phoma terrestris assays and 5-6 weeks for Verticillium spp. and C. coccodes (black dot).

Metalaxyl Resistant Pythium Soil and Culture Assay

The soil assay determines what percent of the total Pythium spp. population present in the soil exhibit resistance to metalaxyl. The assay can also determine if Pythium spp. recovered from infected plant material are resistant to metalaxyl. The fee for each of these assays is $40.

Silver Scurf and Black Dot Testing of Potato Tubers

Silver scurf and black dot tuber assays are conducted on seed and market tubers. The fee for this service is $50.00 per lot to assess incidence and severity of one of the diseases (i.e., silver scurf or black dot,) and $65.00 to assess the lot for both diseases.

Directions for Submitting Samples

It is important that plant samples are properly submitted to the laboratory to aid in successful and timely disease diagnosis. Please follow the instructions below when submitting a sample.

Note: Failure to recover or confirm an organism from a sample does not establish the plant or field to be free of that organism.

1. Collect Samples

Send or bring in as much of the plant as possible. Pathogen infection may occur in locations of the plant body that are distant from where the disease symptoms occur (e.g., infection of roots can result in wilting above ground). If possible, bring in roots, stems, leaves, flowers, and even the soil around roots.

If possible, submit healthy plant samples with the diseased plant samples. It is useful to compare diseased plants to health plants when developing a diagnosis.

It is important that plant disease samples arrive to the laboratory in the best possible condition. Put plants in a paper bag and put paper bag in a box for shipping. Pack brittle samples in dry packing material (e.g., paper towels) so they aren’t crushed during shipment. Do not put samples in wet paper towels or in sealed plastic bags. This will cause the plant tissue to rot and will make diagnosing the problem difficult or impossible. If you are concerned that the sample will dry out before it gets to the lab, wrap cut stem ends in a dry paper towel and place wrapped ends in a plastic bag. Secure plastic bag to stems with rubber bands. Keep samples cool until shipping and mail samples early in the week.

If sending soil samples for fungi testing:

Take 4-10 soil samples from different locations within the area of concern and combine them in a sealable plastic bag or soil sample bag of appropriate size. Usually one quart of soil is enough to run all soil fungi tests.

For large areas (e.g., agriculture fields), it might be useful to submit more than one soil sample per field. For example, one sample from the north, south, east, and west quadrants of the field. If submitting soil from an area where plants are diseased, it can be helpful to submit a second soil sample from an area where plants are healthy for comparison.

Put soil samples in a sturdy box and be sure to secure the sample bag’s opening so it does not spill its contents during shipment.

If preparing potato tuber samples for bacterial ring rot testing of a seed lot:

Randomly select the required number of tubers (i.e., usually 4,600). These are best collected randomly at harvest but can come from across the top of the entire pile. Place the tubers, in groups of 200, in a plastic container lined with a new garbage bag. For example, a sample of 4,600 tubers would require 23 subsamples of 200 tubers. Note that submission of fewer than 4,600 tuber samples will not generally be adequate to assy a seed lot for BRR.

Tuber core samples are then taken from each of the subsamples using a 13mm melon baller.

To clean the melon baller, first wash it with soap and water and then disinfect it by dipping the METAL portion of the tool in 95-100% alcohol and passing it through a flame. Allow the alcohol to completely burn off the melon baller before using. If this is not an option, disinfect the tool with a standard commercial disinfectant, replacing the disinfectant as needed. Clean the melon baller between each seed lot but not between each subsample of a seed lot.

When the tool is ready to use, take a sample from each tuber at the stolon (i.e., stem) end containing as much of the vascular ring as possible. Melon ballers should NOT be larger than 13mm, but can be as small as 10 mm.

Place the cores from the 200 tuber subsample in a 1 quart plastic Ziploc bag and seal. Make sure each bag is labeled with seed lot information and subsample number.

The garbage bag containing the tubers can now be removed, closed, and labeled. It is recommended that tuber samples be kept until all testing is complete.

Tuber core samples should be stored in the refrigerator at 4ºC (39ºF) and brought to the laboratory as soon as possible. Schedule submission with the plant pathology laboratory. Cores should NOT be stored for more than a few days before submission.

2. Complete a Plant Pathology Sample Submission Form

Proper and timely diagnoses also require as much background information about the disease sample as possible. Fill in as much of the correct sample submission form as possible. Sample processing may be delayed if a sample submission form is not included with shipped samples. Below are sample submission forms for:

General plant disease diagnosis

Alfalfa for Verticillium albo-atrum (Vaa) screening

Seed lot testing for bacterial ring rot (BRR)

3. Send Samples to the Plant Pathology Lab

Plant or soil samples can be submitted by bringing the sample to the OSU-HAREC Plant Pathology Laboratory or main office, or by mailing samples via USPS, FedEx, or UPS to the following address:

Extension Plant Pathology Laboratory
C/O Kenneth Frost
Oregon State University – Hermiston Ag. Research & Extension Center
2121 S. 1st Street
Hermiston, OR 97838

Digital pictures of the plant symptoms in the field can also be useful and can be sent to the lab or E-mailed to Kenneth Frost at: kenneth.frost@oregonstate.edu

Reports can be E-mailed as a PDF, faxed, or sent as a hard copy along with the invoice for testing fees. Reports can also be relayed via telephone upon request.