Seven winter wheat and 18 spring wheat fields were surveyed for stripe rust in the Lethbridge, Vulcan, Newell and Taber counties southern Alberta. The recent hot dry weather in southern Alberta has slowed the rate of spread of the pathogen. Fields in the Vulcan and Newell Counties were showing signs of drought stress.
In general, stripe rust is well established in winter wheat in the above counties but was not recorded to any extent in spring wheat fields. Even among the winter wheat fields surveyed, its occurrence continues to be patchy. The majority of the winter wheat fields still had trace to light levels, although approximately 30 per cent of the fields had moderate to severe levels. Producers are encouraged to go out and routinely monitor their wheat fields for the presence of the long, bright orange stripes on the upper leaves. Most winter wheat acreage is beyond the developmental stage permissible for spraying.
For individuals considering spraying spring wheat fields with a fungicide, the following is recommended:
1) Only consider spraying if the spring wheat variety is rated intermediate to susceptible. Durum varieties are highly resistant and do not require spraying. AC Carberry, AC Lillian, AC Muchmore, Pasteur, CDC Go, Sadash and AC Andrew are considered moderately resistant to resistant and should not require spraying. Glenn is intermediate and Barrie is susceptible and should be monitored for disease progression. Producers should check with the Varieties of Cereal and Oilseed Crops for Alberta to verify the stripe rust resistance rating for their seeded spring wheat variety. Those varieties with ratings of intermediate to susceptible should be monitored for stripe rust infection before spraying.
2) Spray wheat when infection levels approach or exceed an average 1 infected plant/square metre.
3) Fungicide applications should be timed to protect the last 2 leaves that emerge (the flag and flag minus 1 leaves) because they contribute most to grain yield and quality.
Producers may now be considering winter wheat options for this fall. Radiant is susceptible to stripe rust and should be replaced with newer, stripe rust resistant varieties. For traditional dryland regions in western Canada, the variety Moats is a good choice. For irrigated production and in parkland regions, Flourish or AAC Gateway are recommended. All three have stripe rust resistance and exhibit similar levels of winter hardiness.