Disease Prevention and Control - Illinois Vegetable Garden Guide - University of Illinois Extension

Disease Prevention and Control

Diseases often cause serious vegetable losses. Some cause the seed to decay or seedlings to die before emergence. Others attack roots, stems, and fruits, causing leaf spots, wilts, cankers, or fruit rots. Vegetable diseases may be carried on the seed or in the soil or be spread by insects.

anthrocnose on cucumber

Resistant varieties. Disease-resistant varieties have been developed for a number of vegetables. Such varieties are moderately to highly resistant to one or more specific diseases (see Table 1). Any gardener who has had vegetable losses due to a disease should, if possible, use a variety resistant to that disease.

Sanitation. Diseases can be controlled by using only disease-free seed and plants, by controlling weeds which serve as sources of infection for plant diseases, and by removing and destroying old plants as soon as the crop has been harvested. Do not cultivate when plants are wet as this spreads plant diseases.

Rotation. Disease organisms in the garden soil can be reduced by not growing a given vegetable or its relatives for more than one year in the same location. Rotate related crops from one side of the garden to the other.

Insect control. Insects may carry disease organisms over winter. They also spread these organisms from wild to cultivated plants and from diseased to healthy plants in the garden. Diligent insect control will reduce such damage.

Fungicide sprays or dusts. Many leaf and fruit diseases can be prevented by applying the right fungicide at the right time. To obtain effective control; (1) all aboveground plant surfaces must be covered with the fungicide, (2) applications should start before the disease appears, and (3) applications at 5- to l0-day intervals must be repeated during humid or wet weather when conditions are favorable for disease development. If you encounter disease problems on your plants, check with your local extension office garden center for proper identification of the disease and the proper remedy.

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