What Is Killing My Tomato Plants?

Corky Root

• Corky root, or Pyrenochaeta lycopersici, occurs in the natural growing environment but is more severe in the greenhouse. Environmental factors, such as cool soil conditions, help this soil fungus to spread. Plants that have been exposed to this fungus start out with their growing points dying back. The roots then begin to turn black and become irregular in shape. Roots begin to exhibit lesions that are cracked and the plant dies quickly when it begins to fruit. Fumigate the soil as soon as symptoms appear to reduce tomato plant loss.

Broomrape

• Broomrape, or Orobanche, is a parasitic flowering plant that has yellow and white stringy stems. The plant starts out as seeds that lay near the soil line. Once the seeds germinate, the plant attaches itself to the root system of the tomato plant. It absorbs food from the roots and starves the tomato plant. Plants that have broomrape should be pulled up. If the contaminated area is large, the soil will need to be fumigated.

Early Blight

• Early blight, or Alternaria solani, shows up on a tomato plant as a sunken lesion that is brown and elongated on the stem. It can occur anywhere on the plant but is especially harmful if the lesion occurs at the base of the plant. If the lesion is at the base, the plant will die. Early blight occurs during periods of warm and wet weather. To control early blight, do not get the leaves wet, and apply a fungicide when symptoms first appear.

Cutworm

• Cutworms appear in the spring when the field or garden space is tilled. Caterpillars that have been feeding on weeds and other plants will move to the young plants. The caterpillars will cut off the young plants at soil level and feed on them during the evening.

Phytophthora Root Rot

• Phytophthora root rot, or Phytophthora parasitica, is caused by environmental issues. Soil that is compacted and water-logged is more susceptible to this problem. To prevent, avoid compacting the soil and do not plant tomatoes in an area that holds water. Plants with phytophthora root rot have lesions on their stem near the soil line. These lesions become brown and sunken, eventually moving around the stem and girdling it. This will cause the plant to wilt and die quickly.