Potato Pest and Disease Prevention

Colorado potato beetle
(Leptinotarsa decemlineata)

Yellow and black striped beetles lay orange eggs on leaf undersides. Brick red larvae eat leaves and flowers. 

Resistant varieties (‘King Harry’), row covers, straw mulch, crop rotation, hand picking, spinosad. 

Slugs and snails Soft-bodied mollusks, with or without shells, chew holes in leaves at night or during rainy weather. No evening watering, hand picking, trapping, encouraging ground beetles and other natural predators with enhanced habitats, practice delayed or reduced mulching.

Flea beetles
(Epitrix cucumeris)

Tiny black beetles chew numerous small round holes in leaves. Second generation may tunnel into tubers.

Tolerate light damage, or use spinosad to control serious infestations.

Scab
(Streptomyces species)

Soilborne bacteria cause corky patches to form on potato skins. Affected potatoes are good to eat, but less than beautiful. Rotate with nonrelated crops, maintain constant soil moisture, use resistant varieties, do not use any kind of manure.

Early blight
(Alternaria solani)

Widespread fungal disease causes brown spots to form on leaves. Encouraged by wet weather and the presence of mature, failing plants. Maintain wide spacing and use drip irrigation to keep leaves dry. Harvest plants before the disease becomes severe.

Late blight
(Phytophthora infestans)

Devastating fungal disease encouraged by mild, wet weather; causes leaves to wilt and turn brown within a few days.

Resistant varieties; early planting, wide spacing to help keep leaves dry.