Eddie Wheeler

Several homeowners have recently had a concern about disorders on their tomatoes. Tomatoes are subject to a number of diseases and disorders. Tomato plants can develop disorders that distort plants and blemish the fruit.

Physiological disorders are not diseases, caused by bacteria, fungus, or virus. Common disorders include leaf roll, blossom end rot, cracking, catfacing, sunscald, and blossom drop. These disorders can sometimes be difficult to control; however, by recognizing the causes, they can possibly be prevented.

The following physiological disorders represent some of the more common tomato problems. Leaf roll or leaf curl is very common, but it doesn’t affect fruit production. It usually occurs after periods of heavy rains, when the soil is very wet. Older leaves are most severely affected, rolling up until they touch. Some varieties are more prone to leaf roll than others, plant tomatoes in well-drained soil to avoid this problem.

Blossom-end rot appears as large round, dry brown to black and sunken leathery areas on the blossom end of the fruit. Blossom-end rot is caused by a lack of calcium in developing fruit. This can occur even when there is an ample supply of calcium in the soil. Extreme fluctuations in soil moisture and extended periods of extremely wet weather can encourage blossom-end rot. To help prevent this disorder, maintain even soil moisture levels by applying mulch. Mulch can also help moderate soil temperature and keep the fruit clean. Also maintain good overall soil nutrient levels through good fertility and regular soil testing.

Tomatoes can often start to crack during warm, rainy periods, particularly after a lengthy dry spell. The fruits crack by simply expanding to fast. To avoid cracking problems, select resistant varieties and keep soil moisture evenly distributed.

Catfacing is a deformity that occurs during the formation of the flower.

The fruits are misshapen and have scars on the blossom end of the tomato. It can be caused by cool temperatures during blooming. Damage from the herbicide 2,4-D can also cause fruit to catface. Large-fruited tomato varieties tomato are more susceptible to catfacing.

Sometimes green or ripening tomatoes get too much sun exposure, the result is often sunscald. The first symptom is a yellow-white patch that appears on the side of the fruit facing the sun, the area will get larger as the fruit ripens and become grayish-white. To prevent sunscald, maintain adequate foliage on the plants. Control foliage diseases and avoid over pruning to encourage plants to develop and retain protective foliage.

Blossom drop may occur on tomato plants, the earliest blooms may fall off without setting fruit. Blossom drop is usually the result of cool night temperatures below 55 F. Blossom drop can also occur later in the season when day temperatures are consistently above 90 F or when night time temperatures remain above 75 F. Following good cultural practices like mulching, proper watering and fertilization can be helpful in producing healthy, delicious tomatoes.

(Eddie Wheeler works out of an office on the ground floor of the Marshall County Courthouse in Guntersville. He can be reached at (256) 582-2009 or via email at wheeled@aces.edu.)

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