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To spray or not to spray

To spray or not to spray

A MPSG report offers some tips to decide if you need to apply foliar fungicide on your peas

By Kate Ayers
Staff Writer

You may need to apply foliar fungicides on your peas but you should weigh multiple factors when making this decision.

In Manitoba, the crop’s vegetative stage ranges from the tenth above-ground node to forming flower buds. Even though tendrils are beginning to knit together, the canopy is not closed yet, a Manitoba Pulse and Soybean Growers (MPSG) Bean Report said yesterday.

When considering foliar applications, producers should begin scouting for disease symptoms in peas at late vegetative stages and throughout flowering, the report said.

Producers should ensure that their “peas are at the correct stage for spraying. Typically, early flowering is when you’d be looking at your application of a fungicide to help protect the plant,” Dennis Lange, industry development specialist for pulses with Manitoba Agriculture, said to today.

Mycosphaerella blight is the most common foliar disease in Manitoba. To control this blight, farmers should apply fungicide on the crop when one flower is open on most plants.

This type of blight “is the disease that can cause some significant yield loss in field pea production,” Lange said.

Producers should target the foliar fungicide on plants’ lower leaves, so it is important to spray before the canopy closes, the report said.

Growers may need to spray a second fungicide application 10 to 14 days later if disease symptoms spread upwards in the canopy and humid weather continues. However, farmers should use a different mode of action.

MPSG has conducted small-plot and farm-scale research on foliar fungicide applications. One application often increased crop yield and a follow-up application typically had a less significant impact, the organization found.

“If you have severe disease in the field, (fungicide) is not going to rectify the problem but spraying it earlier in the season before symptoms really start (to emerge) is key,” Lange said.

Additional factors that producers should take into account are canopy thickness, moisture levels and length of rotation, Lange added.

If you are still unsure if your crop requires a fungicide application, check out the Saskatchewan Pulse Growers’ Fungicide Decision Support Checklist.

This time of year, farmers should also watch for pea aphids.

Farmers have not yet reported pea aphids this season but producers have just begun scouting for this pest. Scouting should start when 50 to 75 per cent of the crop is in early flower.

Generally, the economic threshold for pea aphids is two to three aphids per plant tip.


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