By Ron Friesen
Sources: Agronomist from an NSG Dealer
If you’re a soybean grower using seed treatment in hopes of getting higher yields, you may be disappointed. But that shouldn’t be the reason for using it.
The main goal of seed treatment is to guard against soil diseases and improve crop establishment, not necessarily to increase production, industry officials say.
Preventing disease is especially important in a year when the spring is cool and wet. These are ideal conditions for root rot and seedling diseases to damage soybeans after seeding and during emergence.
“It is important to use treatments, as some diseases are more prevalent in the cool, damp conditions that exist during planting,” says Jennifer Kreway, Richardson Pioneer’s provincial agronomist in Regina.
Diseases are not only linked to cool, wet soils, Kreway adds. Seed treatment is appropriate for a range of fungal diseases under varying conditions.
Soybean seed treatments come as fungicide-only or with an insecticide to protect against early-season insect pests as well as soil-borne diseases.
It’s estimated, up to 80 percent of soybean growers use seed treatment in one form or another. Most seed companies and agri-retailers sell pre-treated seed unless growers specify they don’t want it treated, says Cassandra Tkachuk, production specialist for Manitoba Pulse and Soybean Growers (MPSG).
Whether or not to use seed treatment should be decided on a case-by-case basis, Tkachuk says. Factors to consider include the history of a field and soil conditions at planting.
“The first thing to know if you should or shouldn’t use it is to know the risk in the field. That comes from scouting, seeing what’s in the field and diagnosing whether or not you have seedling diseases, root rot or early season insect pressure,” says Tkachuk.
“It keeps coming back to the overall risk in a field and knowing the overall disease pressure.”
“With a seed treatment cost of $10/unit, a soybean price of $11/bushel, a seeding rate of 190,000 seeds/acre and an average yield difference of one bushel/acre, the use of a fungicide + insecticide seed treatment is not economical, based on these results,” an MPSG factsheet concludes.
But that’s not the way to look at it, says Terry Buss, a Manitoba farm production extension specialist in Beausejour. He says the most important consideration for seed treatment is to prevent disease, not just to increase production.
Buss suggests this simple way of determining if your soybean field has disease pressure or not. Go down to your local dollar store and buy a 28.25-inch diameter hula hoop. Go out into the field, drop the hoop on the ground and count the number of seedlings within its circumference. If you count between 14 and 16 plants inside the hoop, you’re probably on your way to getting a good seed density target of 140,000 to 160,000 live plants per acre. If there are fewer than 14 to 16 plants within the hoop, you could be experiencing disease problems.
“If you’re not hitting the target and you notice you’re losing yield and class because of root rot, because that’s the thing seed treatments and fungicides protect you from, then that’s probably a reason to start using them,” says Buss.
“You’re not going to get a benefit from seed treatment every year. But in bad years, you are.”