Tomato Blossom-end Rot Preventable

Thomas J. Koske  |  10/4/2004 4:23:37 AM

Hot growing temperatures invite blossom-end rot on tomatoes, peppers and eggplants. But an LSU AgCenter horticulturist says the problem is preventable. See story.

Distributed 06/01/01

As summer heat sets in, tomatoes may show many disorders. One common fruit problem is blossom-end rot, or BER, according to an LSU AgCenter horticulturist. 

"These plants aren't fond of temperatures above the low 80s," says AgCenter horticulturist Dr. Tom Koske, noting that the problem also can be found on pepper and eggplant.

"BER is non-pathogenic, that is, it doesn't cause disease, but it can cause affected fruit to die," the horticulturist says, explaining that it occurs when a plant's demand for calcium exceeds its ability to supply calcium to the blossom end. 

BER appears as a flattened, black, leathery lesion on the bottom or blossom end of the fruit. As it extends into the fruit, the plant's low calcium concentration will cause affected zone to fall apart and die.

Several factors contribute to BER. "Low soil calcium levels are an obvious choice," Koske says, "but this is not always the case."

Medium soil levels may be insufficient at times of high demand. High levels of competing soil nutrients, such as aluminum, magnesium, potassium, sodium and ammonium, will hinder calcium uptake. When soluble soil salts are high, they, too, will reduce calcium. Calcium is carried into the plant by water; thus, drought conditions can bring on BER.

"Prevention is probable with best management practices," Koske says, recommending the following actions.

- Add lime to adjust soil pH to around 6.5.

- Add calcium to a soil with a pH 6 or higher by applying gypsum.

- Use nitrate (NO3) form of nitrogen as the major N source and keep ammonium (NH4) N as a minor component. Avoid the use of urea nitrogen. Avoid high N fertility in general.

- Mulch plants to avoid fluctuations in soil moisture, and don't allow plants to experience drought. Avoid very wet soils or very drought-like soils.

- Spray calcium as a commercial stop rot material at first occurrence of BER, or use calcium nitrate at 3 tablespoons per gallon as a weekly foliar spray. Results may be negligible, however.

For additional information about gardening , contact an extension agent in your parish LSU AgCenter office. 

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Source: Tom Koske - (225) 578-2222, or tkoske@agcenter.lsu.edu.

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