Blossom-end rot is a brown, leathery rot developing on or near the blossom-end of the fruit. It starts with a dry brown, dime-sized lesion and increases in diameter as the condition worsens.

Perhaps you are one of many folks having trouble with your tomatoes. Specifically, maybe you’ve noticed brown spots near the base of the fruit.

The spots start out small but continue to increase in size. What is this disease and what can you do to get rid of it?

If it is any consolation, you are not alone; growers everywhere have the same tomato malady. The culprit is blossom-end rot (BER), and it is a physiological disorder, not a disease.

It is easily identified as a brown, leathery rot developing on or near the blossom-end of the fruit. It starts with a dry brown, dime-sized lesion and increases in diameter as the condition worsens. In time, the lesions often become covered with a black mold.

BER occurs as a result of calcium deficiency within the plant. This deficiency is typically induced by fluctuations in the plant’s water supply. Because calcium is not a highly “mobile” element in the plant, even brief changes in the water supply can cause BER.

Droughty soil or damage to the roots from excessive or improper cultivation (severe root pruning) can restrict water intake, preventing the plant from getting the calcium that it needs. Also, if plants are growing in highly acidic soil or are getting too much water from heavy rain, over-irrigation or high relative humidity, they can develop calcium deficiency and BER.

To control BER, take the following steps:

• Keep the pH of the soil at 6.0-6.5. Perform a soil test and apply the recommended rate of lime, using dolomitic or high-calcium limestone. This step should be taken 2-4 months before planting tomatoes;

• Apply the required amount of fertilizer when necessary based on soil test results for tomatoes. Applying too much fertilizer at one time can induce BER. Following soil-test recommendations is the surest way to fertilize properly;

• Use mulches like pine straw, composted sawdust or newspapers to conserve moisture;

• Give your plants adequate water. Tomato plants need about 1.5 inches of water per week during fruiting. Extreme fluctuations in soil moisture can result in a greater incidence of BER;

• Drench the root zone with a calcium solution at the rate of 4 level tablespoons of calcium nitrate or calcium chloride per gallon of water if your plants develop BER. If day temperatures are greater than 85-90 degrees, do not use calcium chloride, as foliage burn can occur. Calcium nitrate is the better option for our hot summer days;

• Try growing several varieties and keep notes as to their performance; some tomato varieties tend to be more sensitive to conditions that cause BER; and

• Remove infected fruits if you experience severe problems with BER. Once a fruit develops BER, it will not regrow or repair the infected area. In fact, the damaged area could serve as an entry point for disease-causing bacteria or fungi.

In general, it’s easier and cheaper to take steps early to prevent blossom end rot in tomatoes than it is to treat the problem once it shows up.

— For information on topics related to the home and garden, contact any office of the Alabama Cooperative Extension System. The Limestone County Office is at 1109 W. Market St. in Athens. Office hours are 8 a.m.-4:30 p.m. Mondays through Fridays. For more information, call 256-232-5510 or visit www.aces.edu.