Early seeding has reduced the threat of powdery mildew in peas, but farmers should still monitor their fields.
Ray McVicar, a Saskatchewan Agriculture special crops specialist, said Kumulus DF is a registered fungicide for powdery mildew in peas. However, it is a protectant and does not cure leaves already diseased.
“So producers should identify the disease early by walking their fields during the last two weeks of July,” McVicar said. “If fungicide application is necessary, spray water volumes should be kept high to ensure proper coverage of all the crop foliage. Repeat applications may be required at seven to 10-day intervals if the same weather conditions that favour the disease persist.
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“Growers who have used Kumulus DF also recommend that sprayers be thoroughly flushed soon after application to prevent plugging.”
Penny Pearse, plant disease specialist, said symptoms include white, powdery spots on lower leaves and stems that can spread to the entire plant. Severely affected crops are covered in a white mat of powdery spores and may appear to have a bluish or silvery sheen. The underside of infected leaves turn yellow below the powdery infection.
“Early infections reduce the usable leaf area, stunt plant growth and affect the development of the pods and seeds. The disease can reduce yield, delay maturity and make it difficult to do a proper job of desiccating the crop,” said Pearse.
On crops with pods and seeds already developed, the disease may look bad, but it will have little economic impact, said McVicar. Seeding early-maturing varieties is recommended.