5–7 minute read

Garden chemicals

Always follow the label directions. The label explains how to use a chemical properly and safely. Use chemicals only on those crops listed on the label, applying at the recommended rate and time and in the manner stated on the label. Obey all precautions listed on the label for using a pesticide safely.

If an insecticide is truly needed, try to limit harm to the desired species. Most plants that produce fruits, pods or ears can stand a 10–20% loss of leaves without loss of potential yields. Do not spray at the first sign of leaf feeding.

Organic methods

Alternatives to garden chemicals can be extremely effective. Some of the best management techniques are preventive in nature and easily accomplished.

Soil prep

Till or hand-turn the soil well in advance of planting. Insects such as wireworms, for which there is no good control, are more abundant in gardens that were recently turfgrass. The garden should be well tilled and free of weeds, grass, and woody material at least 30 days before planting. Fall tilling is even better. This exposes pests that live near the surface of the soil to natural enemies and weather and destroys insects in crop residues.

Plant rotation

See Crop rotation.

Plant selection

Choose adapted varieties with resistance or tolerance to nematodes, other insects, and the diseases common here. Purchase transplants that are free of insects and disease symptoms (such as leaf spots or blights). Avoid transplants that are already flowering.

Planting dates

Follow the recommended planting date(s) listed for each vegetable. Vegetables planted out of season are very susceptible to many pests. Plant as early in the spring (or as late in the fall, depending on the crop) as is safely possible. Use protective covers for cold-sensitive plants.

Intercropping

Mix vegetables from different families in your planting scheme rather than planting each vegetable in large blocks. This helps to prevent build-up of insects.

Mechanical barriers
  • Cutworms
    Place a collar around the plant. The collar can be made from a bottomless plastic cup or a waxed cardboard carton and should extend a few inches above and at least 1″ below the surface of the ground.
  • Insects
    Use lightweight row covers (floating row covers) as a barrier. Put in place at planting with lots of excess material to leave room for the growing plant, then remove when plants that need bees for pollination begin to flower (i.e., vegetables of the Cucurbitacae family).
Weeds

Control weeds in and around the garden because they can be a source of insects and diseases.
Outsmart the Weeds in Vegetable Gardens

Culture

Keep plants vigorously growing and in a state of good health by supplying appropriate amounts of water and fertilizer. A healthy plant is often able to survive insect attack. Too much nitrogen, however, can make plants more inviting to aphids and whiteflies.

Monitoring

Monitor twice weekly for pest and disease problems.

Harvesting

Harvest crops such as tomatoes, peppers, squash, and beans as soon as they are ripe. Over-ripe fruits often invite insect problems.

Sanitation

As soon as a plant or crop is no longer productive, remove it from the garden and compost or dispose of it.

Environmental & cultural problems

Seedlings die shortly after emergence

This problem is most likely to occur with beans, peas, vine crops, and sweet corn. The presence of soil-borne fungi and planting in cold, wet soils are the main causes. The situation can usually be avoided by planting treated seeds in warm soil.

Broccoli flowers before heads mature

This situation is likely to occur if the plants have been stunted by poor growing conditions or if the plants have been set too late in the spring. Broccoli needs cool weather for best head formation.

Cabbage heads split

Certain varieties are more prone to this condition than others. However, heavy rains after the heads are almost mature will often cause splitting. Twisting or pulling the cabbage head to break some of the roots will decrease the amount of water the cabbage absorbs and thus reduce splitting.

Corn ears do not fill properly

Poor pollination due to hot, dry weather is likely the cause. Because corn is wind-pollinated, planting in blocks of 3–4 rows rather than one long row works best. Too much nitrogen in the soil, low potassium levels, and insects feeding on the silks may contribute to the problem.

Bitter cucumbers

Older plants, low fertility, drought conditions, and high temperatures contribute to bitterness in cucumbers. Maintaining adequate moisture, mulching the soil, and fertilizing properly will delay or possibly prevent bitterness. Most bitterness can be removed by peeling off a thicker portion of the skin during preparation.

Cantaloupes with poor flavor

Poor taste in cantaloupes is caused by too much water during the last week of vine growth. Try to avoid watering the plants just before harvest. Nothing can be done about excessive rainfall during this critical period.

Poor fruit set
  • Vine crops
    Squash, cucumbers, cantaloupe, and other vine crops produce both male and female blossoms and poor pollination can be a problem. First, bees are needed to transfer pollen from male to female blossoms, and blossoms are open only one day for pollination. Second, weather influences flower sex. Warm and long days prompt male flower production, while cool and shorter days favor female flower production. The blossoms need to overlap for pollination to occur.
  • Peppers
    Peppers prefer night temperatures below 68°, although small-fruited cultivars are more tolerant of temperature extremes. Pollen production is compromised at temperatures under 61° or over 89°. Even watering is also important. Moisture stress during flowering may cause small fruit or flowers to drop off.
  • Tomatoes
    Temperature extremes prevent fruit from forming. Night temperatures below 60° or above 75° or day temperatures above 90° usually keep tomato plants from setting fruit. High temperatures reduce both pollen production and the viability of the plant ovary.
Tomatoes rot on blossom end

This type of rot is caused by lack of calcium in the blossom end of the fruit. It can be reduced by proper liming and fertilization, mulching, and maintaining a uniform moisture supply.


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