Few things are as important as a complete seed test. Home germination tests might save you some cash at the outset, but performance in the field depends on more than just “does the seed sprout?” Lab tests to determine seedling vigour and in-seed pathogens are just as important as a germination test.
After last fall’s wacky, prolonged harvest period, several issues are coming to light as seed-testing labs work through this year’s seed lots. Glyphosate damage, increased levels of several diseases and sprouting invisible to the naked eye are rampant. Kelly Hansen is an accredited seed analyst and runs Prairie Diagnostic Seed Lab at Weyburn, Sask. She’s working through her busiest season and what she sees isn’t pretty. Chemical damage, disease and sprouting in seed lots can have disastrous effects. “We had such a rough fall and no one could have foreseen we’d get such a great heat wave late in the season, so there were guys who went out and sprayed (before the late heat wave) in hopes of
getting some dry-down happening,” she says.
Spraying a growing crop carries germination risk to
seed, she says. To complicate matters, it’s not always apparent if a seed is still developing.
Because of this unknown, if you sprayed glyphosate or desiccant on any crops last fall and are planning to use that seed, Hansen says it’s imperative to test it for germ and vigour first. Peas and any other crop sprayed while still filling will take up some chemical. “The seeds may germinate, but they’ll show chemical damage shortly after sprouting and won’t become vigorous plants,” she says.
WET FALL MEANS FUNGUS WITH SEED
Crops left in the swath — and even those left standing — endured some wet weather last fall. Hansen sees the evidence of that in higher levels of sclerotinia and botyrtis. The usual suspects are there as well, including Cochliobolus sativus, a cause of root rot. “Some of these diseases can be handled completely with a seed treatment, so it’s important to know if they’re present,” she says. Some diseases, such as fusarium, may be suppressed and not cause a problem right away, but once introduced into a field, you always run the risk of more severe infestations later.
SPROUTING AND HEATING
Anyone can spot severe sprouting in a seed lot, but the germination process begins long before we see plant parts start to emerge. “Chemical reactions take place inside the seed, using up nutrients and enzymes, long before we can see a change,” Hansen says. If this process starts in the field or in the bin — whether you see it or not — it will set back the germination and vigour of the seed lot. A seed only has so many nutrients and enzymes. At some point, it runs out of gas. A seed test can indicate if early sprouting has happened and to what degree.
Heating in the bin can also reduce germination and vigour. Because many crops went in the bin a little wet or warm, Hansen has seen more evidence of heating damage.
Germination levels will tell you how many seeds will sprout, but vigour tests give you an indication what percentage of seeds are likely to form viable plants. This is important for setting seeding rates, for one thing. The difference between the two tests can’t be accurately tested at home.
“You can have 90 per cent germ but only 60 per cent vigour,” Hansen says, which can translate to some serious stand establishment issues. “Seed with poor vigour says, for a vigorous seedling to be up and out of the ground faster. If emergence takes longer because of poor conditions and you’ve got a less vigorous seed in the ground, you could see weaker plants that put up fewer tillers or stalks, eventually impacting yield.
“I’ve seen guys spend thousands — I’m
not exaggerating — having to reseed a crop all because they didn’t test the
seed going into the ground.”
With germination percentage, seed vigour and disease results in hand, it’s now time to make some decisions. Not all of them are easy.
Depending on the crop type and diseases present, sometimes a seed treatment is all you need, but there are several instances where finding an alternative seed source is the best option. At times, choosing another crop entirely is the most prudent decision, but not a popular one.
Faye Dokken-Bouchard, Saskatchewan’s plant disease specialist, says it’s always risky using poor seed, especially when it comes to disease. Many seed treatments only suppress the disease, not eliminate it, she says. “Even if the crop germinates fine, the disease could always impact the crop later and affect yield.”
You could also see longer-term implications to using dirty seed. “Even if the disease can be suppressed or controlled with a seed treatment, you’re still introducing inoculum into a field,” says Dokken-Bouchard. Depending on the field history or what you plan to seed next, you may not want to risk introducing more
disease to an already dirty field or a new disease to a previously clean field.
Saskatchewan Ministry of Agriculture has a table (posted on this page) to help you decide what to do when certain diseases show up in a test. It’s important to note that the threshold for certain diseases is very low. Often finding a new seed source is truly the best option. More complete tables for both cereals and pulses can be found through the Ministry of Agriculture’s web-site at www.agriculture.gov.sk.ca.Click on “About Agriculture” on
the left-hand side, then choose “Production,” then “Crop diseases” for the full tables, or talk to your local agronomist.
This year, farmers may be tempted to tighten lentil rotations to make the most of favourable crop prices. Dokken-Bouchard is concerned about this increasing the disease risk. “Diseases such as ascochyta and sclerotinia can live on several host crops,” she says. Tighter rotations mean a higher risk to each of these crops and a buildup of inoculum in the soil. A seed test is a good indication of what is lurking in the field, whether you see evidence of disease or not.
You’ll pay roughly $150 per seed lot for a complete germination, vigour and disease test. On the surface, that can seem like a lot of money if all the tests come back as healthy, but if the test catches a vigour problem or higher disease levels than you anticipated, the test becomes money invested rather than spent.
“I’ve seen guys spend thousands — I’m not exaggerating — having to reseed a crop all because they didn’t test the seed going into the ground,” Hansen says. Spending $150 to save thousands is a common reality, she says.
Lyndsey Smith is a Grainews field editor based in Lumsden, Sask. She takes over as editor starting with the March 22 issue. You can reach her at [email protected]or 306-731-3637.