Early Blight & Brown Leaf Spot of Potato

Early Blight & Brown Leaf Spot of Potato

Early blight (caused by Alternaria solani) is a common problem in southern Idaho.  This disease can destroy leaves and cause tuber blemishes after harvest.  Varieties differ in susceptibility to this disease.  Additionally, plant fertility is an important component to reducing the severity of disease.  Many fungicides are available which can help suppress disease to manageable levels.  A related disease called brown leaf spot (caused by Alternaria alternata) can also be problematic on potatoes, but this is not seen often in southern Idaho.  More information on our recent research in this area can be found here.

See how different fungicide regimes performed against early blight and white mold for disease control, yield, and economic return.

When Quadris was introduced for managing foliar diseases of potatoes in 1998, growers' ability to control early blight increased dramatically.  Other strobilurin products have followed.  Recently fungicide resistance has been observed for isolates of the early blight fungus.  What does this mean for using strobilurin fungicides in the field?