Leaf rust was found in a winter wheat trial near Carman, Manitoba.

 

Leaf rust overwinters in the southern United States and is blown into the southern Prairies by prevailing winds. It is recognized by its characteristic orange-red pustules that erupt from the upper surface of leaves. Rust spots are very small, circular or elongated, and are vivid orange red in colour.

 

Yield loss and reduction of test weight are related to disease severity and time of infection. Yield losses of 30 percent to 40 percent have been recorded when severe infection occurred before flowering and damage on the flag leaf was high (> 60 percent to 100 percent). 

 

However, if severe leaf rust does not occur until dough stages of kernel development or beyond, yield losses may be in the range of 5 percent to 15 percent.

 

The good news is leaf rust can be managed by timely fungicide applications.  If the disease pressure, weather conditions and crop yield potential warrant application, foliar fungicides should be applied before the disease is well-established in the crop to provide maximum benefit. There are numerous products available for the control of leaf rust; please refer to the Guide to Field Crop Protection.

 

 

For more information on leaf rust, its symptoms, biology, and control measures, visit MAFRD’s website at http://www.gov.mb.ca/agriculture/crops/plant-diseases/leaf-rust-wheat-barley-oats.html.