Reducing fungi populations in a field is the oldest way of treating fungal-based plant disease.
It is also time consuming and usually involves long-term crop rotations that force producers to avoid certain profitable crops, such as canola and sunflower.
Contans WG has been popular for controlling sclerotinia in France for a decade. It might have stayed there if not for a casual meeting between a senior manager of a Canadian pesticide company and a German businessperson and scientist.
“I guess they didn’t know how important a disease sclerotinia was for Canadian farmers,” said Garth Render of UAP Canada.
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In parts of Manitoba and in other moist areas of the Prairies where sclerotinia flourishes, treatment is limited to spraying after the disease is established in hopes of containing its spread.
Contans WG, a biological fungicide, is applied to the soil ahead of the crop’s appearance in the field.
It is a fungus and works based on the premise that the major source of sclerotinia is present in the field before the crop is seeded, rather than being carried in on the wind later. It attacks the sclerotinia while it is resting in the plant litter and top layers of soil.
While resisting, sclerotinia gives off small amounts of a gas that the Contans fungus, coniothyrium minitans, identifies and uses to find the fungus.
But to give the coniothyrium minitans fungus time to grow and kill the sclerotinia, it must be applied in either large amounts that would not be cost effective for field crops, or applied early enough to spend time in the soil at temperatures above 5 C and below 30 C.
Render said the product is best if it’s spring applied with a cereal or other rotational crop before the susceptible plants arrive in the field, or fall applied and allowed to work for a few weeks in the fall before planting a canola, pulse or sunflower in spring.
“We aren’t saying it’s going to eliminate sclerotinia risk completely, but it dramatically reduces the risk,” he said.
The product is attached to sugar granules and is water dispersible through sprayers or irrigation equipment.
For this season, the product will be released in 12 kilogram pails that can treat as many as 60 acres. The dealer suggested list price is $34 per kilogram. By autumn, a 20 kg bag is expected to be available.
At its lowest rate of about $5 per acre, producers should apply Contans WG in the spring the year before they plan to seed a crop that could be affected by sclerotinia.
Render said farmers should consult with a dealer about rates and timing.
“If you want it to be effective on canola after (just) 45 days you are going to need to push those rates up, putting more of the fungus out there, to work for you,” he said about spring application.
A tricky part about Contains WG is that it must be kept cold to remain alive in transport and storage.
It is very stable frozen and can last years at -18 C and weeks at 0 C.
However, UAP said the goal for farmers is to order what they need and apply it as soon as possible.
“We won’t be accepting returns of material from dealers or farmers,” he said.
For more information, contact Garth Render at 204-888-1369 or www.uap.ca.
