Common Problems in the Vegetable Garden

Many factors can cause problems in the vegetable garden, either by themselves or by interacting with other factors. These include insects and other pests, infectious diseases, and environmental factors such as weather, nutrient deficiencies, and chemical or physical injury. Some problems can be prevented or treated, while others cannot be controlled.

Healthy plants are more resistant to damage from all causes, so choosing the proper plants and giving them the proper growing conditions should be the first line of defense. Encouraging healthy plants and using natural, non-toxic methods of control when possible are part of an approach referred to as Integrated Pest Management.


Planning and Planting

  • A sunny, well-drained site is best for most vegetables. Perform a soil test and add any recommended amendments. Adding compost will help improve the texture of the soil.
  • Select disease resistant varieties or use treated seed. Purchase from a reputable source, and ex-amine plants before purchasing.
  • Don’t plant too early - cool temperatures and wet soil can encourage disease. Time your planting to avoid peak insect infestations if possible.
  • Good air circulation is important, so avoid over-crowding, and use supports to keep plants off the ground.



Plants in the same family are susceptible to many of the same problems. To reduce problems from soil-borne diseases and overwintering insects, it is best to avoid planting in the same location every year. A 3- or 4-year rotation between crop families is best if possible. Crop families include:

  • Cole Crops: broccoli, cabbage, cauliflower, radish, turnip, rutabaga, mustard greens, Brussels sprouts
  • Vine Crops: melons, squash, cucumbers, pumpkin
  • Tomato: tomato, pepper, eggplant, potato
  • Legume: beans, peas


During the Growing Season

Give plants adequate water but avoid overwatering. Water is one of the ways diseases can be spread, so try to keep water off the leaves by watering in the morning or using drip irrigation. Also avoid working in the garden when leaves are wet.

Use only enough fertilizer to meet the needs of the plants. Excess nitrogen can make the plant more susceptible to disease.

Mulching will help maintain consistent moisture levels, as well as discourage weeds and soil-borne diseases and minimize physiological disorders such as blossom-end rot.

Weeds compete with plants for resources and can also harbor insects and diseases.

Extreme weather conditions sometimes cause fruits to fail to set on tomatoes, beans, and peppers, resulting in a dropping of the affected flowers. Night temperatures below 55°F. in the spring and hot, drying winds in the summer are the chief causes of blossom drop in Illinois, although insects, diseases, and weed killers may sometimes be a factor. Hot temperatures can cause physiological leaf roll of tomatoes, an alarming, but often harmless issue.


Other Measures

  • Monitor the garden regularly in order to catch problems early when they are easier to deal with.
  • Garden debris can harbor pests and diseases. Dispose of all plant residue in the fall or as plants cease producing. Remove diseased plants as soon as they are discovered and destroy (do not compost).
  • Keep garden tools clean. Disinfect with a 10% bleach solution after working with infected plants.
  • Encourage beneficial insects and natural predators, and control insects that carry disease.
  • Use physical barriers such as floating row covers or cutworm collars to protect plants from insects and insect-borne diseases.


Pesticide Damage to Crops

In recent years much damage has been caused in some home gardens and yards by the careless use of 2,4-D and related weed-control chemicals. Often 2,4-D drifts in from nearby lawns and ag fields. Tomatoes, melons, sweet potatoes, and beans are some of the vegetables susceptible to 2,4-D. Avoid using these products where possible. If you must use 2,4-D or similar weed killers, follow these precautions:

  • Spray only when wind is quiet.
  • Keep pressure very low and nozzle directed downward.
  • Do not apply insecticides or fungicides with a sprayer that has been used for weed killers. It is exceedingly difficult to remove all of the residue from a sprayer contaminated with 2,4-D.
  • Spray when high temperatures will not exceed 85 degrees Fahrenheit
  • Read and follow the directions on pesticide labels

If You See a Problem

Positively identify the problem before starting treatment, especially with chemical controls. There are many books and online resources available or consult your local Extension office.

Next, decide if the problem is serious enough to require treatment. Plants can tolerate a certain number of insects, and some diseases, especially late in the season, may not affect production significantly.

Start with non-chemical controls if available. If chemical controls are required, use the least toxic one that is effective, and follow all label directions.