An easy-to-grow cold-weather crop, potatoes (Solanum tuberosum) fare best in U.S. Department of Agriculture plant hardiness zones 1 thorough 7. A nutritious food source, the leaves, stems and tubers of the potato plant can prove irresistible to some insects, both above ground and below ground. Common pests include potato leafhoppers, flea beetles, Colorado potato beetles, grubs and worms.
Potato leafhoppers pierce the leaf of the potato plant, sucking out the juice from the leaves. They are small, triangle-shaped and green, making them difficult to spot. With a sharp beak, potato leafhoppers easily puncture the surface of leaves undetected, as they spend most of their time on the underside of the leaves. Potato leafhoppers will leave brown edges on the sides of the leaves as they suck out the sap to the point of leaf death. In extreme cases, a potato leafhopper infestation can lead to poor tuber production as the more damaged leaves there are, the lower the amount of nutrition provided through photosynthesis.
Around 1/16 inch long, flea beetles are tiny green, black or brown-colored insects. Oval flea beetles present themselves most commonly early on in the growing season, as they prefer to feast on young, tender potato plants. Because of their size, flea beetles may be undetectable until small holes appear on the leaves. Flea beetle larvae can also infect the tubers of the plant underground, leaving tunnels and holes that make the potatoes susceptible to fungal and bacterial infections. A heavy infestation of flea beetles can lead to a poor harvest or, in extreme cases, no harvest at all as a serious infestation can kill young potato plants.
Colorado Potato Beetle
Also known as the potato bug, the Colorado potato beetle larvae will kill an entire crop in very short order if infestations are left untreated. The larvae live through the winter in the soil, emerging when the weather warms. The larvae will eat the mature foliage of the potato plant and can decimate an entire crop in under two weeks if left untreated. Adult Colorado potato beetles will lay their eggs on the undersides of the potato leaves, causing the cycle to start over again with a new crop and a new season.
In addition to above-ground pests, potatoes are susceptible to grubs and wire worms, which can cause damage below ground, often undetectable until harvest. Grubs can sometimes damage the tubers to such an extent that the foliage above ground dies, an indication that the plants and tubers are severely damaged. Wire worms will burrow through the tubers, creating small tunnels and open areas that leave the tuber damaged and more susceptible to soil-born diseases from fungi and bacteria.