Economic thresholds generally do not exist for plant pathogens and nematodes in Idaho field and row crops.  The following table instead lists pesticide application timing recommendations for disease and nematode management.

Sugarbeets

Pathogen		Pesticide	Timing
	Cercospora leaf spot (Cercospora beticola)	Protective fungicides	Field should be sprayed with a protective fungicide when disease averages 0.5% infection (about 12 spots per leaf).
	Powdery mildew (Erysiphe polygoni)	Sulfur fungicides	Begin applying sulfur fungicides when mildew is first observed. If necessary, repeat application to maintain 10% or lower leaf area diseased through the growing season.

References:  Pacific Northwest Disease Control Handbook, 2000.

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