Alternaria Leaf Spot

HOSTS

• Cucurbits

DESCRIPTION

Alternaria leaf spot is a foliar disease caused by the fungus Alternaria cucumerina that thrives in wet and warm conditions.

BIOLOGY

Alternaria cucumerina can survive on infected plant debris in the soil for up to two years. When the weather is wet and warm, the fungus will release spores that are spread by the wind, water, and equipment. Infected seeds can also introduce the disease to fields and gardens.

SYMPTOMS

• Round foliar lesions with concentric rings and yellow halos 
• Spots of black fungal growth on leaves 
• Severe infections will cause entire leaves to die 

GENERAL MANAGEMENT

• Plant certified disease-free seed 
• Rotate with unsusceptible crops for at least two years 
• Avoid watering practices, such as overhead irrigation, that result in wet leaves for prolonged periods 
• Crop debris should be incorporated into the soil 
• Plow or till plant debris into the soil to speed up decomposition

FUNGICIDES