Some Common Diseases of Garden Potatoes

Problems growing potatoes can vary widely depending on location and weather. One of the best ways for the home gardener to prevent potato disease is to plant each year's crop in a different part of the garden so soil borne diseases will not be perpetuated from year to year.

Perhaps the most aggravating problem in the home garden is verticullum wilt and/or fusarium wilt. Wilts cannot be treated, either chemically or organically. You will recognize these wilts when the lower leaves of the potato plants droop and turn yellow; they may have small brown spots, and the plants die. Wilts can be carried by tubers, although infected tubers are still edible. Wilts survive in the soil, especially in areas where tomatoes, peppers, or eggplant have been grown and may also have had the disease. The wilts can live in the soil for 7 years, and even certified seed potatoes are not always free. Rotating crops will help avoid perpetuating wilts. But the most important thing the home gardener can do is to clean up all refuse from infected plants and burn it. Kennebec potatoes are particularly susceptible to wilt, and planting a different variety for a few years sometimes helps in the home garden.

Blights are another problem. They are caused by wind blown fungi which will cause spots on the leaves and defoliation. Since the number of leaves is reduced, the tuber yield is reduced. Some blights also affect tomatoes, and can overwinter in compost piles that are not properly turned and decomposed. Chemical fungicides are available. Copper based organic fungicides are often effective. Again, good garden sanitation is the best remedy.

Blackleg is a bacterial disease that is carried in almost all tubers and seed potatoes. It doesn't present a problem unless weather conditions are right for its growth. Cool wet weather at planting will cause blackleg, which rots the seed potato. If vine growth has been made and the weather becomes cool and wet, blackleg causes the vines to turn black and slimy at the soil surface and below, and the tubers will rot. Injury from cultivation can also cause blackleg, and once it occurs it can set the stage for other kinds of tuber rot to set in.

Hollow Heart/Brown Center is pictured. It is caused when conditions favor rapid tissue growth, which results in a cavity in the center of the potato. The tubers are edible, but the hollow cavity often causes rot which ruins the storage life of the tubers. There isn't much that can be done about this since the rapid tuber development is a result of growing conditions.

Good organic practices will help gardeners avoid potato problems. Enrich the soil with compost that has reached hot temperatures during the decomposition process. Destroy culled potatoes and vines that have any signs of disease by burning them away from the garden. Clean up plant refuse and weeds, and till the garden soil well after potatoes are harvested. Rotate crops. And keep an eye open for problems so they can be treated early.