By KARLA DENNIS
Are you happily counting the tomatoes in your garden or bemoaning your tomato failures this year? As I’m writing this article, I’m patiently waiting on several plum tomatoes to turn red so that I can make sauce. My patience will pay off only if my small fencing is enough to deter my rooster, who likes to eat them just before I like to pick them.
While most gardeners are not competing with a chicken for their tomatoes, there are plenty of other forces in our environment — insects, fungi and bacteria — that pose threats to the success of a harvest. It’s a wonder that we even continue our efforts! But with proven methods and attentive care, you can have the satisfaction of tasting a homegrown, ripe, juicy tomato straight from the vine.
First, beware of the tomato hornworm. This large green caterpillar with a frightening looking horn can munch away and destroy your tomato plant in short order.
Tomato hornworms, the larvae of the Sphinx moth, are best controlled with regular visits to the garden. When you see them, pick them off the plant and squish them with your shoe or plop them into a cup of soapy water.
Are your tomatoes ripening unevenly with hard white spots under the skin? Damage of this nature can be caused by stink bugs, which are also best controlled with hand picking and squishing or plopping into soapy water. Because stink bugs don’t inflict damage until after the fruit is set, insecticides are only recommended in extreme cases.
Reducing stink bug damage in the garden can start in the winter months when they move into your home and take up residence under siding and in storage boxes. Simply vacuum them up and destroy. Also, keep your garden weeded to eliminate a breeding habitat and you should be able to keep stink bugs under control.
White-spotted and uneven coloring on your tomatoes can also be caused by an insect called a thrip. However, thrip damage would most likely be seen before the point of fruiting as they are vectors for the tomato spotted wilt virus.
Tomato spotted wilt virus causes bronze- or dark-colored leaves, dark-colored streaks on the stem, and even plant dieback. Because this virus is not exclusive to tomato plants, it is best to control thrips with an insecticide at the first sign of them in your garden.
Early blight and Septoria leaf spot are fungal infections that start as spots on the leaves. Septoria leaf spot has a silver center as the spots grow out, and often there is yellowing around the spots that’s followed quickly by yellowing of the leaf and stem.
The spots of early blight are usually more irregular and can also be seen on the main stems and fruits. Careful use of a fungicide and removal and destruction of infected plant parts may control this for a time, but prevention is your best defense.
How do you prevent these fungi? Keep weeds clear, use a soil barrier, and water in ways that do not cause the soil to splash onto the plants.
One most devastating, though not common, tomato disease is tomato pith necrosis, a bacterial infection caused by Pseudomonas and Pectobacterium caratovorum. It’s usually seen in early planted tomatoes when the nights are cool and the humidity is high.
Symptoms include top wilting and splitting of the main stem with adventitious roots along the stems. Unfortunately, once this disease sets in, plants that are affected will lost. Prevention is the only treatment for this disease.
A common noninfectious disorder with tomatoes is blossom-end rot. This condition appears as a black, sunken spot on the blossom end of the tomato. It is caused by either too much or too little water. To control this disorder, mulch around your plants and try to limit water to about 1 inch per week.
If you have more questions about growing tomatoes, please contact the Ohio State University Extension office and our team of Hancock County Master Gardener Volunteers. Visit us on Facebook at “Master Gardeners of Hancock County Ohio.”
Karla Dennis is a Master Gardener Volunteer for the Ohio State University Extension in Hancock County.