Controls | 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. |