The Top 7 Problems When Growing Tomatoes

— Written By and last updated by Top Tomato Growing Problems

For the home gardener, tomato season is often something you look forward to all year. How wonderful is it to put that transplant or starter tomato in the ground and realize that in 6-8 weeks you’ll have slabs of tart, juicy goodness for those tomato sandwiches! Tomato dreams are easily dashed, though, by a host of issues that these tender plants can face as they struggle to reach their full height and yield.

Let’s look at the top seven tomato-growing problems facing everyone’s favorite summer crop, and also some solutions that can help you tackle them in turn.

  1. Cutworm – Most cutworms cut off stems of plants at or near the soil line. They curl up into a tight C shape when disturbed. Guard the plant base from cutworms with a wax paper collar about 3” high (2” above ground & 1” below).
  2. Aphids – These plant lice cause the greatest damage when they suck juices from the plants. They usually feed in clusters. Several applications of soapy water are quite effective to control them.
  3. Tomato Hornworm or Tobacco Hornworm – Hornworms feed on tomatoes, peppers, potatoes and related plants. You’ll know you are dealing with them if you spot dark green droppings left by the larvae feeding on the leaves. You can pick them off by hand or use biologic pesticides to control them such as Dipel or Thuricide.
  4. Early Blight – This disease produces brown to black, target-like spots on older leaves. If severe, the fungus also attacks stems and fruit. Sanitation is the best control and can be prevented by using a Copper Fungicide or chemical pesticides such as Daconil. Remove all diseased plant tissue on the ground. Do not plant tomatoes in the same place next year.
  5. Septoria Leaf Spot – If you are beginning to notice brown spots that cause the plant to defoliate from the ground up, you are probably dealing with this fungus. First, try to improve air circulation around the plant, since the fungus is often caused by overly humid conditions. You can also control by spraying with a fungicide prior to infection and continuing weekly or bi-weekly throughout the season.
  6. Blossom End Rot – This disease is non-parasitic and is caused by a calcium deficiency in the developing fruit. The affected area of the tomato darkens and enlarges in a widening circle. The calcium deficiency may be due to a lack of calcium uptake from the soil or to extreme fluctuations in water supply. Make sure your soil pH is between 6.0-6.5 to maximize nutrient availability. Since blossom-end rot is also associated with extremes in water supply, it is important to try to regulate the moisture supply in the soil. Plants need 1” of water per week. 
  7. Bacterial Blight – This is another type of blight that can appear in our area. It consists of angular brown spots on pepper and tomato leaves which can spread to the fruit. To control this, apply a copper fungicide prior to, or as soon as, any symptoms are noticed. Continue throughout the season based on label recommendations. This disease is typically seed borne and controls may be ineffective leaving removal as the only option.