Cercospora Leaf Spot

(click image to enlarge) Symptoms:
• Circular spots 3-5 mm
• Brownish to reddish purple border with tan to light brown center
• Individual lesions will run together and form larger spots eventually killing the leaf

Epidemiology:
• Survives 1-2 years
• Spores travel up to 300 ft
• Optimum conditions for infection 77-95° F and 5-8 hrs of free moisture or > 90% relative humidity

Control:
• Control overhead irrigation to minimize leaf wetness
• Increase air circulation by reducing stand
• Separate previously infected fields from new plantings by at least 300 ft
• Minimum of 3 year crop rotation to allow for microbial breakdown