YOU ARE HERE: Central Kentucky Home→Collections→Fruit

Tomato problems may not be disease related

July 10, 2008|DAN GRIGSON

If your tomatoes aren't maturing like you want them to, it might be because of poor environmental conditions. A number of problems can result from poor environmental conditions, including blossom drop, blossom-end rot, cracks in the fruit, sun scalded fruit, catfacing and zippers on fruit.

Blossom drop is caused by excessively high or low night temperatures. Most tomato varieties won't set fruit unless temperatures are between 55 and 75 degrees F for at least part of the night. Sprays that supposedly prevent blossom drop may help somewhat if low temperatures are the cause but spray fruits often are misshapen and seedless. This is seldom a problem in Kentucky since summer night temperatures rarely drop below 55 degrees.

Blossom-end rot develops when environmental conditions prevent the proper distribution of calcium in the plant. The result is a leathery spot on the blossom end of the fruit. We get a lot of calls each year about this problem which most people describe as tomatoes rotting on the vine especially on the bottom of the fruit. Under stressful conditions, low soil moisture in addition to hot, dry winds, calcium moves into the leaves and bypasses the fruit, causing the leathery spot at the fruit's end. Wet conditions followed by a period of hot dry days also makes this problem worse.

Water frequently and mulch to maintain fairly consistent soil moisture to help prevent blossom-end rot. If water and mulch do not correct the problem, foliar sprays of calcium chloride or calcium nitrate may be warranted. Add four tablespoons of calcium chloride or calcium nitrate to one gallon of water and apply it two to three time beginning about a month after setting. As it recurs, spray weekly with calcium chloride. It is also important to keep adequate lime levels in the soil. You can overdue lime so soil test to determine lime and fertility needs.

Cracks in the fruit develop when the fruit grows too rapidly. The problem manifests itself in either concentric rings at the stem end of the fruit or radial cracks at the stem end. Planting crack-resistant varieties and watering and mulching to prevent rapid fluctuations in soil moisture will help you avoid problems with cracked fruit.

Sun scald occurs when immature fruit are exposed to direct sunlight. Yellow or white patches develop as symptoms of the problem. Sun scald often starts when insects or diseases defoliate plants and fruits are exposed to the sunlight. Unsupported plants that sprawl also can lead to the problem. Caging tomatoes, staking them, or using the Florida-weave system helps prevent sprawling of plants. And protecting plants against foliar disease and tomato hornworm can also help protect the immature fruit.

Catfacing and zippers are deformations of fruit when fruit set occurs during cool and cloudy weather. The blossom sticks to the developing small fruit and causes puckers to develop. Usually only a few fruit are affected. Large fruited varieties are much more susceptible than those with smaller fruit.

For more information on growing tomatoes, stop by the U.K. Extension Office in Stanford an pick up your free copy of Home Vegetable Gardening in Kentucky.

|

|

|