UAP Has New Biocontrol For Sclerotinia

“If it (Contans) is used by more and more growers the regional approach would be a good approach because the overall inoculum would be reduced.”

– VIKRAM BISHT

Manitoba sunflower growers finally have a tool in the battle to protect their crops from sclerotinia, a potentially devastating fungal disease that also attacks canola and other crops such as edible beans and soybeans.

While there are chemical fungicides registered to suppress sclerotinia in canola and beans, there are none for sunflowers – until now. This spring limited quantities of a new biological control called Contans will be available through UAP, the firm’s marketing manager Garth Render told reporters last week.

And while sunflower growers will especially welcome Contans, the product can be used to suppress sclerotinia in all susceptible crops.

“It’s a totally new way of thinking about controlling sclerotinia in crops in Western Canada,” Render said. “It’s pre-emergent so you’re no longer treating the crop, you’re treating the soil.”

Contans, which is a naturally occurring, living fungi found in soil (Coniothyrium minitans), kills sclerotia when it contacts them.

Sclerotia are hard, black organisms that produce apothecia, which then produce the ascospores that infect plants with sclerotinia.

Sclerotia also produce mycelium in the soil, which causes the basal rot form of sclerotinia in sunflowers when it contacts the plant’s roots.

Contans isn’t a “silver bullet” and because it’s a living organism, proper storage, transport and application are essential to its success, Render said.

“Its two enemies are temperature in transportation and ultraviolet light,” he said

Contans has a five-year shelf life when stored at -18 C. It will be shipped frozen from UAP’s Regina warehouse in coolers the day before the product is to be applied.

When not in the soil fungi started dying at temperatures of 20 C and above.

“If you go out spraying for the day and leave this stuff barbecuing in the back of your pickup, the stuff you’re spraying by the end of the day is not going to be in good shape,” Render said.

The optimum soil temperature for Contans is 15 to 25 C.

“It’s active between 5 and 30 C and will hibernate outside of that range.”

Because Contans, which is expected to be approved for use on organic crops, is so different from chemical fungicides, only limited quantities from a select number of retailers will be available this spring.

Contans also needs time to work – at least 90 days. Ideally Contans will be applied to a field 12 months before it’s seeded to a susceptible crop.

TRAVELLING SPORES

Contans is a wettable granule, which is mixed with water and sprayed with conventional equipment on fields. It needs to be harrowed into the soil unless application is followed by a quarter-inch of rain or applied through irrigation equipment, Render said.

If applied properly, Contans will reduce the number of sclerotia in a treated field, cutting

the number of ascospores produced. But ascospores can blow in from neighbouring fields. How far spores travel and remain viable varies with the weather.

“Under the right conditions a few (sclerotinia) spores blowing in can be quite devastating,” Vikram Bisht, a plant pathologist with Manitoba Agriculture, Food and Rural Initiatives, said in an interview March 29.

“If it (Contans) is used by more and more growers the regional approach would be a good approach because the overall inoculum would be reduced.”

Bisht wants to do some demonstration trials with Contans this year.

UAP sees four application strategies for Contans:

Long-term sanitation of the soil.

Short-term sanitation of the soil.

Creation of a protective barrier in the soil.

Preventing sclerotia from contaminating future crops.

Long-term soil sanitation is designed to destroy new and existing sclerotia to protect the next susceptible crop grown in that field.

Contans is sprayed on harvested crop residue just before cultivation or late in the fall or spring at a rate of 0.4 kg per acre costing $13.50 an acre. In the spring a non-susceptible crop would be seeded. The next fall or spring another 0.4 kg would be applied and in the spring sunflowers would be seeded.

Short-term sanitation is designed to destroy sclerotia to protect the current crop using pre-seeding rates of 0.8 kg for field crops and 1.6 kg an acre to protect potato or vegetable crops.

Barrier protection is aimed at early “in-row” protection of crops like sunflowers and potatoes against mycelium-based infection.

Contans would be applied before planting or just after planting or emergence in a band spray. The product must either be mechanically incorporated or drenched into the soil.

The fourth strategy is to treat infected crop residue in the fall at the 0.4 kg/ac. rate, preventing viable sclerotia from getting into the soil.

“We see that as being a fairly popular treatment in Manitoba in bean (areas) or in heavy canola rotation as well,” Render said. [email protected]

About the author

Reporter

Allan Dawson

Allan Dawson is a reporter with the Manitoba Co-operator based near Miami, Man. Covering agriculture since 1980, Dawson has spent most of his career with the Co-operator except for several years with Farmers’ Independent Weekly and before that a Morden-Winkler area radio station.

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