Insect & Disease Control for Organic Garders- Part I

One of the most troublesome problems faced by organic gardeners is pest control- specifically insects, diseases and weeds. We’ll save our discussion of organic weed control techniques for another time, but there are several techniques that can be used to keep insects and diseases below your tolerance threshold. However, organic gardeners must realize that a higher level of insect and disease damage will be present when using an organic growing system. Deciding how much damage you can tolerate on your plants will help to pinpoint when control measures are needed.

Following are several techniques integral to an organic gardening system, and which will help prevent the onset of disease and insect problems.

1. Buy resistant varieties. Selecting cultivars with resistance or tolerance to disease attack helps reduce damage. Examples include tomatoes with resistance to fusarium, verticillium, and nematodes and cucumbers tolerant to bacterial wilt. When gardening without the use of pesticides, select cultivars that are the most resistant or tolerant to pest problems. For more information on resistant cultivars, check garden catalogues, seed packages or Selected Vegetable Cultivars for Nebraska.
   

2. Rotate vegetable families. Crop rotation can reduce insect and disease damage since pests and disease-causing organisms tend to increase when their host is continuously grown in the same location. For crop rotation to be effective, you need to know the genetic relationship between common garden crops. For example, you should not follow tomatoes with peppers since these plants are closely related and many of the same diseases and insects attack both. Crop rotation is especially effective with soil home diseases. Rotation periods are three to five years and may be difficult in a small garden; however, container plantings can become part of the rotation for added space.
   

3. Use good garden sanitation. Removing diseased plants will limit the spread of disease to healthy plants. Many pathogens survive between growing seasons on diseased plant material, so removing diseased plants, fruits and vegetables from the garden in fall will lower the inoculum level the following spring. Keep gardens weed-free, since weeds often serve as a reservoir of insect and disease problems.
   

4. Avoid overhead irrigation. Many diseases require leaf wetness for infection to occur, so plan to use drip irrigation next year to keep foliage dry and conserve water. Avoid placing plants too closely together, because it results in slower air movement through plant foliage, slower leaf drying and often greater disease problems.
   

5. Mulch. Summer mulch prevents rain-splash of soil containing fungal spores onto the undersides of leaves, which is the starting point for many fungal infections.
   

6. Buy healthy, high quality plants. Many disease problems are brought into the garden accidentally through diseased plant material, so be sure to buy only healthy plants from reputable growers.

Next week we’ll discuss methods used by organic gardeners to control pest problems, after they have started.