Summertime Tomato Woes

— Written By ascheck and last updated by

Tomatoes are one of the most widely cultivated plants in the home garden. This is for good reason because they are a delicious food with great nutritional benefits. Also, the taste of a fresh tomato straight off the vine cannot be beat. Unfortunately for the home gardener there are many diseases and pests that plague tomato plants, especially at this time of the year. Whether it’s an insect, fungus, virus, or bacteria that attacks your plants the end result can be just as devastating, dead plants. During the mid to late summer harvesting fresh tasty fruit can be a real struggle.

A multitude of insect pests plague tomatoes each year. One of the most well known is the hornworm, which grows to be over 3 inches long and can defoliate entire plants in a matter of days. Its green body, white spots, and large horns on its head make hornworms easy to identify. In small gardens picking them off your plants easily controls them, but if they have white eggs on their backs leave them, as the eggs will hatch into parasitic wasps that will then feed on other hornworms. Another major insect pests of tomatoes are tomato fruit worms that feed on ripening tomatoes. Tomato fruit worms are yellowish white to brown with dark heads and grow to be around a little over an inch long. Most gardeners use sevin or similar insecticides to control them.

Many diseases begin to make an appearance this time of year on tomatoes as well. Fungi cause some such as fusarium and verticillium wilt as well as late and southern blight. The first symptoms of the fungal diseases are generally wilting and yellowing leaves often accompanied by lesions and/or spots. Bacterial spot is another disease that creates damaging spots that can also lead to reduced yields and unhealthy plants. In all cases the best control is to prevent these in the first place by planting resistant varieties and following the correct cultural controls.

Last but not least are viral diseases that effect tomato plants such as tomato spotted wilt virus and tobacco mosaic virus. Pests including thrips and whiteflies generally transmit these viruses. Therefore, controlling your pest levels will play a big part in reducing viral outbreaks. There are also varieties of tomatoes that are resistant to these viruses. Planting tomatoes away from tobacco plants will also help reduce the outbreak of these diseases because the viruses can be transmitted between both species.

In addition to pests and disease tomatoes are often affected by a disorder known as blossom end rot. Blossom end rot is when the end bottom of tomatoes get black and soft and appear rotten. More times than not blossom end rot is caused insufficient calcium levels, but thankfully prevention is fairly simple. If you see the symptoms a foliar application of a calcium fertilizer will often correct the problem. To prevent blossom end rot conduct a soil test and make sure there are sufficient levels of calcium in your soil before planting.

With the many pests, diseases, and disorders that can plague tomatoes they can surely be frustrating for even the most experienced gardeners. Despite the challenges involved people still manage to grow their own tomatoes every year. If you are struggling try to learn from your mistakes and don’t give up. Selecting good varieties of tomatoes that are resistant to multiple diseases is one of the best steps that one can take in order to avoid frustration and to get the largest possible crop of tomatoes. Also, make sure any seeds or seedlings are free of pests and disease when you are planting your garden in the spring to keep from introducing any new problems to your garden. The challenge certainly does make the end result of fresh juicy tomatoes even more rewarding.

For more information on tomatoes, diseases that affect them, and selecting resistant varieties contact N.C. Cooperative Extension, Lee County Center (919-775-5624).

Alec Check is doing a Horticulture Internship with North Carolina Cooperative Extension in Lee County this summer.