Tomato Root Worms

Symptoms

• Above the soil, you may first notice that a patch of tomatoes in your garden are growing poorly and have yellow foliage. Other susceptible plants -- peppers, eggplant, cucurbits, onions, carrots, okra, peas and beans -- may also show symptoms. If you continue planting susceptible plants in that area of the garden, the problem can spread. Tomatoes infected with root-knot nematode can show symptoms of a nutrient deficiency or drought, even when they have adequate supplies of nutrients and water. Plants often wilt during hot days and then appear normal at night. Some plants may die. Below the soil, infected tomatoes develop short, bushy root systems. The roots develop small, light brown swellings called galls that can fuse to cause severe root swelling.

Damage

• Root-knot nematodes attack the tomato's roots, creating the above- and below-ground symptoms that signal the presence of the disease. Nematode larvae enter the roots, causing the formation of the root galls. Damage to the roots prevents the plant from correctly absorbing water and nutrients, causing it to wilt and show signs of deficiency. Infected plants also become more susceptible to other tomato diseases.

Treatment

• Improving your soil allows other microorganisms to colonize the soil and compete effectively with root-knot nematodes. Aged compost and livestock manures enrich soil and help control nematodes.

  Covering the soil with a clear polyethylene tarp raises temperatures in the soil to levels high enough to destroy nematodes. You have to leave the tarps in place for six to 12 weeks.

  Nematicides can destroy the nematodes found in soil. Most of them must be applied to the soil prior to planting, although you can apply some varieties to the foliage of your existing plants. Always follow the instructions on the label to avoid harm to yourself, your plants and the surrounding environment.

Prevention

• The best approach to root-knot nematodes is preventing them from damaging your plants. Clean out and destroy infected plant material at the end of the season.

  Avoid planting tomatoes or other members of the nightshade family -- potatoes, eggplant or peppers -- in the same part of your garden for multiple years in a row. Whenever possible, allow three to five years to pass between locating nightshade plants in the same spot in the garden.

  If root-knot nematodes are a problem in your garden, plant resistant varieties like Celebrity, Daybreak, Sunny or Super Marzano. The letter N on the plant tag indicates resistance to root-knot nematodes.