Why Should Seeds Be Tested Prior to Planting?
Companies are required by law to test seed health prior to selling.
2017 Winterby Mary Burrows
MSU Extension Plant Pathology Specialist and Professor
The quality of seed impacts plant health in two main ways: vigor and seedborne diseases. Seed vigor includes various properties that determine the ability for the seed to develop into normal seedlings. Companies are required by law to test seed health prior to selling. The presence of prohibited noxious weed seeds generally makes the seed illegal for sale. If restricted weed seed is present, seeds can be sold provided their name and rate of occurrence is within allowable limits in the state it’s being shipped and shown on the analysis tag. The Montana State Seed Laboratory (plantsciences.montana.edu/seedlab/) tests seed’s germination, purity, and other factors. This gives seed purchasers (farmers, gardeners, nurseries, researchers, etc.) a good idea of how much of the seed, when planted, will germinate, and if any weed seeds are contaminating the seed lot.
Growers often don’t realize that ‘certified’ seed, depending on the standard set by the industry, means only that the seed is certified to be a pure variety and to be free of weed seed. Another aspect of seed testing is to determine if seeds have been contaminated with seedborne and seed-transmitted plant pathogens. Pathogens are bacteria, viruses or other microorganisms that can cause disease. These diseases vary by crop, and can become an issue if introduced into new acres where they can spread quickly. Some examples relevant to Montana include smuts and bunts of cereals, Ascochyta blight of pulses, and blackleg of canola. Infected seed, in most cases, has no visible symptoms of infection. Special laboratory tests can help identify what pathogens are present in seed: and once the pathogen is identified, mitigating management steps can be taken. Seedborne pathogens are not necessarily transmitted to the next generation (progeny). If the pathogen is transmitted to progeny, it is called a seed-transmitted pathogen. The seed transmission rate varies by the host plant, pathogen, and a number of other factors including the timing of infection of the parent plant, the variety of the host, the strain of the pathogen, and the environmental conditions during disease development.
Testing seed for pathogens is extremely important for the pulse crop industry for a number of reasons. First, a comprehensive pathogen test such as that conducted by the Regional Pulse Crop Diagnostic Laboratory (plantsciences.montana.edu/pulsecropdiagnosticlab/) notifies the grower of what diseases may be of concern in the crop the following growing season. The lab provides some guidelines formanagement and the Northcentral IPM Center Pulse Crop working group has created a fungicide efficacy table for some diseases. These are available at msuextension.org/plantpath/ and routinely emailed and texted via Montana AgAlerts (mtagalert.org/). Identifying diseases that are seedborne can help growers identify seed lots that they do not want to plant, or that they want to treat with an effective fungicide prior to planting. This type of testing is particularly important for organic growers and growers planting new acres to pulse crops, where prevention is key to disease management.
A second reason seed testing is important to the industry is because most of the pulse crops are exported to other countries that have what are called ‘phytosanitary regulations.’ Governments use this mechanism to keep plant pathogens from moving internationally in seed, and it can also be used as a trade barrier. One example in Montana is testing for Ditylenchus dipsaci, the stem and bulb nematode. This is primarily a nematode on bulb crops such as garlic and onion, but it can infest 450 different plant species, including alfalfa. Montana produced seed has consistently tested free of the nematode, although countries do request the testing for a phytosanitary certificate. To learn more about exports in Montana and phytosanitary certificates, visit the Montana Department of Agriculture website at agr.mt.gov/Topics/Export.
A third reason seed testing is important to the pulse industry is monitoring for new pathogens and new pathogen races, the development of fungicide resistance, and surges in incidence of pathogens. These give the industry an early warning to focus research and education efforts to help sustain the entire industry.
Small gardeners and large-scale farmers alike should buy seed from reputable sources and select varieties with disease-resistance. The rules and standards for testing seed for plant pathogens are set by the International Seed Testing Association (www.seedtest.org/en/home.html). In addition, growers should never save seed from diseased plants where the risk of transmission is high. Planting unhealthy seed can perpetuate a disease situation. Whatever you choose to grow, making sure the seed you select has good vigor and is disease-free can reduce future challenges.
SIDE BAR
To submit a seed sample, place the seed into a tightly sealed container to prevent contamination. Cloth bags, heavy-stock envelopes, and ziplock bags will work. Print an order from the web page: plantsciences.montana.edu/seedlab/submission.html to include with the sample. Send the sample via USPS to Montana State Seed Lab, PO Box 173145, Bozeman, MT 59717-3145 or by FedEx/UPS to 1911 West Lincoln Street, Marsh Labs; Room 40, Bozeman, MT 59718.
Montana State University requires the following for common seeds:
- Small-seeded legumes and grasses (alfalfa, clovers, timothy bluegrasses, etc.): Sandwich size bag filled or ½ quart; 4 oz/¼ pound.
- Wheatgrass, ryegrass, bromegrass, flax or similar-sized seed: 1 quart; 8 oz or ½ pound.
- Cereals, safflower, field peas, lentils or similar-sized seed: Gallon bag filled mostly full. For pulse pathogen testing, submit 3 pounds.
For more information, contact the Seed Lab at 406-994-2141.