Tomato early blight

Tomato early blight is caused by a fungus, Alternaria solani, that overwinters in the soil.

Growing the same crop in the same location year after year not only decreases yields. It sets a gardener up for weed, insect, and disease problems.

By establishing a three-year or four-year rotation sequence and diversifying the crop (and the crop family), gardeners can avoid many problems with soil fertility, weeds, insects, and diseases. Rotate crops by the type of food that is produced (such as fruit, root, stem, or leaves). For example, a gardener may choose to rotate a garden bed for four years beginning with tomato (fruit), followed by beets (root), followed by celery (stem), followed by spinach (leaf). Planting cucumbers followed by cantaloupes and then corn would not be a good option because cantaloupes and cucumbers are both in the cucurbit family, and they are also fruit crops. Tomatoes, eggplants, peppers, and potatoes are all in the nightshade family. Rotating beans, or legumes, through a plot naturally adds nitrogen to the soil through nitrogen-fixing bacteria in the legume roots. Keeping a plot fallow for a year can break an insect or disease cycle. Sowing a cover crop is one way to add nutrients to the soil. If cucumber beetles have been a problem in the past year, then select another crop family to plant in that spot and plant cucumbers as far away from the original plot as possible. This prevents the adult beetles that overwinter nearby from spreading to the new crop of cucumbers.

For more information on crop rotation and other organic gardening methods, visit the NC Extension Gardener Handbook online or call 252-482-6585.

From the NC Extension Gardener Handbook