Manitoba Insect & Disease Update

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.

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 (picture is from May 12th). 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.

                                                
                                                         Photo courtesy of Amber Knaggs.