fields to different crops each year is one of the most important and easily
implemented disease control strategies for farmers. This practice avoids the
buildup of many plant diseases in the soil. The longer the rotation before
coming back to the crop, the less likely a disease will occur.
usually attack members of the same plant family, it is best to avoid planting
crops after each other that belong to the same family. Insect damage may increase when the same crop is planted in the same
area over several years as well. Here are some common vegetables and the
families they belong to.
- Tomato
Family: Tomato, potato, eggplant, peppers - Cucumber
Family: Cucumber, melons, squash, pumpkin, gourd - Lettuce Family: Lettuce, endive, salsify, Jerusalem
artichoke - Onion Family: Onion, garlic, leek, shallot, chive
- Carrot
Family: Carrot, parsnip, parsley, celery - Cabbage
Family: Cabbage, broccoli, cauliflower, Brussels sprouts, kohlrabi, turnip,
radish, Chinese cabbage, kale, collards, rhutabaga - Beet
Family: Beet, Swiss chard, spinach - Pea
Family: Peas, snap bean, lima bean, soybean - Okra
Family: Okra - Corn
Family: Sweet corn, field corn, wheat, barley, oats
choices of crop rotations include Pea Family to Corn Family, Lettuce Family to
Cucumber Family, Cucumber Family to Cabbage Family, and Cucumber Family to Corn
Family. Rotating beans with a grain crop such as barley, oats, rye, wheat, or
field corn or with a forage crop is very beneficial for root-rot control. One
or two years in a grain crop is often long enough to prevent severe root rot
when the field is not heavily infested with this disease.
Some diseases that come
from the soil are not easily controlled by rotation. Such diseases can live a
long time in the soil and are not affected by rotation. Examples include
clubroot that attacks the Cucumber Family, Phytophthora
blight, and Fusarium wilt of several
crops. Other diseases attack so many vegetables that they can survive indefinitely
on many different plants including weeds. These diseases include Sclerotinia, Rhizoctonia, Verticillium and root-knot nematodes.
Many
diseases can survive successfully because they can live on plants and plant
parts left in the field after harvest. However they are unable to survive once
the plants left in the field decompose. Destruction of plants and parts of
plants left in the field after harvest can eliminate this problem. Plowing the
field after harvest and before letting the soil rest can reduce the amount of
disease that will survive.