Fresh, vine-ripened tomatoes are one of the great joys of summer. However, sometimes diseases, pests and/or environmental stresses get in the way of our tomato harvests. I have already gotten several calls and visits about problems with tomato plants. Below are some common issues and potential solutions.
Black area on bottom of tomatoes – This is a sign of blossom end rot. Although it looks like a disease, blossom-end rot is caused by a calcium deficiency, usually aggravated by drought or uneven watering, root damage and/or excess nitrogen. Fortunately, blossom-end rot will usually occur on just a small number of fruits, especially at the beginning of the harvest season. To prevent it, provide sufficient water to plants to keep soil moist throughout the growing season. You can also combat the problem with a calcium chloride sprays applied to the foliage, which may help prevent blossom-end rot on developing fruit.
Fruit cracking and catfacing – Cracks in fruit are generally caused by uneven watering. Use a soaker hose or irrigation system, to apply water directly to the soil, moistening the entire root zone each time you water. Some tomato varieties are more prone to cracking than others. Catfacing is a tomato disorder that causes fruits to develop puckered surfaces and distorted shapes. Bands of tan-colored scar tissue may also run across the blossom end of the fruit. The disorder occurs when weather conditions interfere with proper pollination and fruit development. Heirloom tomato varieties, especially those that produce very large fruit, are particular susceptible to catfacing and growth cracks.
Holes chewed in leaves and fruits – This is a sign of insect pests. Defoliated plants can indicate the presence of a tomato hornworm. This large bright-green caterpillar has white diagonal stripes and a black horn projecting from the rear. Because of their size, they are easy to spot and hand-picking them off and destroying is usually the easiest solution. Very rarely are pesticides used to control them. Holes chewed in tomatoes can be the work of slugs. There is nothing worse than picking a tomato and finding a slug happily working its way through it. Slugs can be thwarted with iron a phosphate-based product. Of course, there are other insect pests that can hurt your tomato crop – aphids, stink bugs, leaf-footed bugs, whiteflies, and fruitworms. The most important thing you can do is scout for pests and then take swift action if needed.
Leaf spotting and rolling – Dark ringed spots and water-soaked lesions on the leaves are usually a sign of a disease. Proper diagnosis is key to be able to perscribe a fungicide to treat. You can limit the spread of most leaf diseases by not getting water on the leaves when watering and not handling plants when they are wet. If overhead irrigation is your only option, time watering for early morning (5:00 to 9:00 am) so that plant foliage dries quickly. Curling or rolling of tomato leaves can be caused by various factors, including environmental stresses, viral infection, and herbicide damage.
If you are experiencing problems with your tomatoes, contact our office and we will try to help diagnosis the issue. You can reach me at clh@uga.edu or 706-795-2281.
