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Blossom end rot

AUBURN UNIVERSITY, Ala. – For many, there is nothing better than eating a tomato sandwich using fresh tomatoes from the garden. Tomatoes are often the most common plants in a basic garden. There are many varieties on the market, each one offering something different. With some areas of the state facing drought conditions, tomato growers could see a problem with blossom-end rot (BER) in their plants.

Blossom-End Rot

Chris Becker, an Alabama Extension coordinator in Limestone County, said BER is a disorder that affects the fruit of a plant.

“Blossom-end rot is an abiotic disorder, caused by nonliving factors,” Becker said. “It starts out as a brown, dime-sized lesion near the blossom-end and increases in diameter as the condition worsens.”

A calcium deficiency causes BER within a plant. This deficiency is usually a result of a change in a plants water supply, or shortage of calcium in the soil. Becker said even a slight change can affect the plant.

“Calcium is not a highly mobile element in a plant,” he said. “Because of this, even brief changes in the water supply can cause blossom-end rot.”

Water intake can often be affected by drought stressed soil and roots damaged from excessive or improper cultivation. This prevents the plant from getting the calcium it needs for healthy growth. Highly acidic soil and areas that have too much water can also cause a calcium deficiency in plants.

Controlling Blossom-End Rot

Becker said growers should remove affected fruits if BER problems become severe.

“Once a fruit develops blossom-end rot, it will not regrow or repair the affected area,” Becker said. “In fact, the damaged area could serve as an entry point for disease-causing bacteria or fungi.”

It is generally easier to prevent blossom-end rot rather than wait and treat the problem. The following are a few tips on controlling blossom-end rot.


During fruiting, tomato plants need about 1.5 inches of water each week. It is important that plants get an adequate amount of water. Extreme changes in soil moisture can increase the chances of a plant getting BER. Use mulches like pine straw, composted sawdust and also newspapers to help conserve moisture.

Becker said if plants develop BER, growers can apply a calcium solution.

“Drench the root zone with the solution at the rate of four level tablespoons of calcium nitrate or calcium chloride per gallon of water,” Becker said. “If day temperatures are greater than 85 to 90 degrees, do not use calcium chloride because foliage burn can occur. Calcium nitrate is the better option for hot days”

Plant Different Varieties

Some tomato varieties tend to be more sensitive to the conditions that cause BER. Becker suggests growing several varieties of tomatoes and keep notes on their performance.

Perform a Soil Test

Becker recommends keeping a pH level between 6.0 and 6.5. Becker said perform a soil test two to four months before planting.

“A soil test will show what levels need to be adjusted. Apply the recommended rate of lime, using dolomitic or high-calcium limestone,” Becker said. “Also, apply fertilizer as recommended, because applying too much fertilizer can induce BER.”

Collecting a soil sample is an easy procedure. For information on how to collect and send a soil sample for testing, visit the Soil, Forage & Water Testing Laboratory’s website. The fee for testing is $7 per sample. Soil test boxes as well as sample forms are available at any county Extension office.

More Information

For more information on blossom-end rot, visit Alabama Extension online or contact your county Extension office.


Featured Image: M.E. Bartolo, Bugwood.org

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