The challenge of tomato problems

By: Nancy Olden - Extension agent

Tomatoes are one of summer’s favorite vegetables, so many try to make sure a big crop is in the future. Tomatoes do have a few problems which need to be addressed.

Blossom End Rot – Do your tomatoes/peppers/melons have dry dark spots on the blossom end? Blossom end rot occurs on tomatoes, peppers, squash, eggplant and watermelons from a lack of calcium in the developing fruit. This disorder results in the decay of fruits and vegetables on their blossom end. These dark spots are the size of a dime that may grow to the size of a half dollar. Blossom end rot is usually most severe following extremes in soil moisture (either too wet or too dry). The rotten area is unsightly but the rest of the fruit is edible.

To reduce blossom end rot, implement the following steps:

1. Lime tomato soils to pH 6.5-6.7. – The dolomitic lime should be worked into the soil 12 inches deep.

2. Fertilize properly – Applying too much fertilizer at one time can result in blossom end rot.

3. Mulch plants –Use straw, pine straw, or newspapers. Mulches conserve moisture and reduce blossom end rot.

4. Irrigate when necessary – Tomato plants require about 1.5 inches of water per week during fruiting. Extreme fluctuations in soil moisture result in greater incidence of blossom end rot.

Nematodes – A huge problem of tomatoes in sandy soil. No pesticides are available to the homeowner. Research tells us to plant brown mustard seed in nematode infected soil after vegetables come out for the season and grown through the winter then tilled in prior to bloom, wait a couple of weeks to start breaking down is the best natural nematicide to control nematodes.

Leaf Spots – There are a number of fungi (early blight, later blight, septoria, ect.) which can cause leafspots especially during periods of rainy weather. Some cause spots on the fruit as well. Most are spread by wind or rain-born spores. Use of a broad-spectrum fungicide labeled for tomatoes on preventative basis will usually stop development of these diseases. Removal of the lower leaves early in the season combined with mulch and watering through a drip/soaker hose, may prevent disease development.

Tomato wilt – Southern bacterial wilt or southern stem rot are the most common problems in this area. Southern bacterial wilt can be identified if you cut open the stem and see a brown discoloration in the vascular tissue or by a bacterial streaming from a stem cutting when placed in a glass of water. In southern stem rot a white mycelium is visible at the base of the plant.

However there is no cure for either of these diseases. Pull up and destroy the affected plants. Since both of these disease organisms live in the soil for years, rotate your plantings within the garden or even better relocate your garden spot. Be sure to grow tomatoes with wilt resistance.

Early blight – Caused by a fungus appearing as irregular brown patches ¼” in diameter with miniature “bulls eye” spots appearing first on lower leaves. The fruit will often develop dark brown sunken lesions near the stem. Treat with a fungicide labeled for tomatoes. Repeat every 7-10 days.

Late Blight – Dark, water soaked patches appear on leaves during humid, wet conditions which eventually cause the leaves to shrivel and turn brown. Treat the same as for Early Blight.

For additional information on your gardens and yards be sure to contact the Bladen County Cooperative Extension (910)862-4591 or come by and visit at the office, 450 Smith Circle Dr. Elizabethtown.

Nancy Olsen is a Bladen County Extension agent. She can be reached at

Nancy Olden

Extension agent