What's wrong with your tomato plants? Here's what to look for.

With summer upon us, you are hopefully finding your vegetable plants in good health and in full production.

It does seem most years, however, that the tomato typically becomes infected with one or more disorders. Though various diseases affect tomato fruits, noninfectious disorders are common, too.

Here are a few non-infectious disorders to keep a watch for.

Blossom end rot in tomatoes

By far the number one question concerns blossom end rot. Blossom end rot is not caused by bacteria or fungus but is a result of a calcium deficiency.

Symptoms first appear as dark-brown or water-soaked spots at the blossom-end of the fruit. As these spots enlarge, they become sunken and often dry rot. Applications of lime or calcium fertilizers before planting can help reduce this problem but typically not solve it completely.

A soil test, testing for pH and calcium can tell you exactly how much lime or calcium to apply.

Certain tomato varieties are tolerant of a calcium deficiency and may make a better choice if your garden is prone to this disorder. Other conditions that could increase incidence levels include excessive soil salts, especially in container gardens, root damage, and uneven watering.

Catfacing in tomatoes

Catfacing causes misshapen fruit with scars often near the blossom end. It results from high nitrogen levels or during cold weather breaks earlier in the season.

Cracking can appear as radial or concentric cracks in the fruit. Cracking occurs most often during extreme environmental changes such as periods of dry weather followed by wet weather or hot day temperatures dropping to low night temperatures.

Proper plant nutrition and irrigation will help to avoid both of these environmental disorders.

Cloudy spot or 'ghost spot' in tomatoes

Although not a disease, cloudy spot or ghost spot is caused by a pest. Feeding damage by the stink bug causes yellowish irregular spots to occur just below the tomato peel.

Close inspection of the damaged area may reveal a small hole caused by the stink bug’s piercing mouthpart. Control cloudy spot with a garden insecticide where excessive damage occurs. Tomatoes are still edible if you cut away the damaged tissue.

Sunscald on tomatoes

During hot, sunny weather, sunscald may occur on the exposed sides of mature green fruit. A white discoloration will develop and damaged tissue will become sunken with a black mold frequently occurring.

This disorder is more common on plants that have lost branches due to breakage or disease. Reducing damage to branches that provide shade to the fruit will eliminate this problem.

Should you use herbicides on tomato plants?

Herbicides used to control weeds in lawns or around your garden can wreck havoc on tomato plants as most are very sensitive to them.

Systemic herbicides can be translocated through the plant resulting in stunted growth, yellow foliage, or twisted stems and leaf cupping. Contact herbicides may cause yellowish or dead spots wherever they are sprayed. Fruits may become excessively enlarged or irregular shaped.

Catfacing mainly occurs on the blossom end of some tomatoes. Following the label on herbicides is your best way to avoid these conditions.

Herbicide damage occurs most often during high temperatures or on windy days since certain chemicals may drift during these conditions. Plants exposed to light herbicide contact may outgrow the symptoms; however plants do not recover from severe herbicide damage.

These are just a few of the problems we often see with tomato’s but good maintenance and cultural practices will go a long way in reducing the damage.

P. Andrew Rideout is the UK Extension Agent for Horticulture and can be reached at [email protected].

This article originally appeared on Evansville Courier & Press: What's wrong with my tomatoes?