Insect levels seen low, stripe rust reported in winter wheat

Manitoba Insect & Disease Update for May 24

Insect pest concerns are currently low overall. There have been some insecticide applications for cutworms in the Northwest, and for flea beetles in canola in the Central and Northwest Regions.

Striped rust has been reported from a winter wheat field; no other plant pathogen activity has been reported.

Stripe rust overwinters in winter wheat

Stripe rust was observed in a winter wheat field near Austin this spring. This field was being monitored by local agronomist, Amber Knaggs, as there were disease issues, including stripe rust, already present last fall. When stripe rust is well-established in the fall and heavy snowfall provides a good insulating layer, the pathogen can overwinter even in harsher climates. Alberta also reported overwintered stripe rust this year, as has been observed in that province in the past.

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The disease was detected over a month ago and the field has been continuously monitored this spring. The disease has not progressed much at this point. Stripe rust typically likes cooler weather with adequate moisture available. Growers in the area surrounding this field should scout both their winter and spring wheat to determine whether the infection has spread. If fields are planted to a variety susceptible to stripe rust, infection is present, and the weather remains conducive to the spread of disease an early fungicide application (at the herbicide timing) may be warranted. For growers in the rest of the province, the main source of inoculum for stripe rust (like stem or leaf rust) remains when large spore loads begin to blow up from the southern United States.

It is interesting to note that in the field where stripe rust was observed, the grower had seeded two varieties, CDC Falcon (rated “S” for stripe rust) and Emerson (rated “MR” for stripe rust). The disease was only detected in the areas seeded to CDC Falcon.

Agronomists, Farmers, Farm Production Extension Specialists, Extension coordinators, and others scouting crops: Please remember to send in reports of insects or plant diseases over the growing season so we can make these updates as complete as possible, and alert farmers and agronomists where and to what degree insects and pathogens are of concern or being controlled. Information can be sent to: John Gavloski (entomologist) at [email protected] (phone: 204-750-0594) or Holly Derksen (plant pathologist) at [email protected] (phone: 204-750-4248).

Click here to view the complete Manitoba Insect & Disease Update on the Manitoba Agriculture website.

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