mbpotatoes.ca

Late blight has been confirmed in Manitoba, today evening, from Rural Municipality of Norfolk Treherne in South Central potato growing region in Manitoba. The region had heavy rains last week in the area. Leaf spot infections appear to be scattered close to the irrigation pivot.  The infected leaf spots have sporulation and there are a few infected stems too (Photos 1 & 2). Samples will be sent for strain identification.

With widespread rains today in the province the conditions will be very favourable for late blight disease.  It is important the all fields are scouted very diligently. Application of translaminar fungicides along with the protectant fungicides should be considered.  In fields with new disease incidence fungicides with “kick-back” effect could be considered.

This is the time for home gardeners to check their tomato and potato plants very carefully for possible late blight infection. Early blight and Septoria leaf spots diseases on tomato are different from late blight disease (Photos 3 & 4). Both diseases normally start from lower leaves, tend to move upwards and often cause some yellowing of leaves. Protectant fungicides may be applied as soon as possible. There are copper fungicide options for organic production.

Early blight disease incidence is increasing in more fields of Rangers; still in the lower canopy (Photo 3). Incidence on Russet Burbank appears to be low.