Tomatoes

County Agent’s Corner

 

 

Well, I think that summer is officially upon us, and nothing says summer like tomatoes. While yours may not be ripe quite yet, there are some things to be looking for now to ensure a delicious, homegrown tomato sandwich is in your future.

When it comes to tomato problems, they fall into three categories – cultural, disease, and insect. Often, you may have issues from more than one source going on at the same time. Let’s visit a minute on each of these.

Cultural issues are not caused by diseases or insects. They are the results of abiotic (non-living) factors such as weather conditions, chemical injury, irregular watering, etc.

Leaf roll is a common cultural issue. The leaves roll upward and may have a leathery or stiff feel. Leaf roll is often seen as temperatures increase rapidly. This issue can also occur during prolonged periods of wet soil conditions or drought. In most cases, the crop is not significantly affected.

Another common cultural issue is herbicide injury. Tomatoes are extremely sensitive and can be severely damaged or killed by drift from nearby sprays of broadleaf weed killers like 2,4-D and dicamba, as well as non-selective herbicides, such as glyphosate, when these chemicals are applied on windy days.

Blossom-end rot is also a frequent issue when growing tomatoes. While the symptoms (water-soaked spots on the bloom end of the fruit) look disease related, they are caused by a calcium deficiency in the plant. There are several contributing factors to this deficiency – periods of cloudy, rainy weather, inconsistent moisture, or cool temperatures. A side-dress application of calcium nitrate is extremely helpful in preventing this issue.

While there are numerous diseases that can affect tomatoes, I would like to focus on one of the most common, early blight.

Early blight is a fungal disease that shows up as brown spots on the older leaves of the plant. As the spots age, they increase in size forming a bull’s- eye pattern. Often, a yellow halo will surround the spots. Spots can also occur on the stems and fruit.

The disease moves vertically through the plant and can kill much of the foliage during periods of high temperatures and humidity. A fungicide spray, such as mancozeb or chlorothalonil, is extremely helpful in preventing this disease. Please read the label for spray rate and frequency.

Now, on to insect pests. Several species of stinkbugs and leaf-footed bugs can cause serious problems in your tomato patch. In fact, they feed on many vegetables that we often plant in our home gardens.

Aphids and whiteflies can also affect plant health. Not only does their feeding activity harm the plant, but they are also vectors of disease. When they pierce the leaf to feed on the sap, they can infect the plant with any number of viral tomato diseases.

The last insect pest that I will mention is a big one – both in size and in the damage they cause. Hornworms grow three to three and a half inches in size and have a large appetite. They can strip the foliage from a plant overnight. This is why it’s important to inspect your plants often. Hornworms and aphids are often the exact color as the tomato leaf, so you need to keep an eye out.

As I eluded to above, the first line of defense with any nuisance insect pest is to scout your garden regularly. Controlling or managing insect pests is much easier when the numbers are small.

In fact, a strong stream of water or hand-picking can eliminate the presence of several nuisance insects. If numbers are large, chemical control may be necessary. Be sure to identify the insect pest first to find the right insecticide for the job. Always read the label for spray rate and frequency recommendations.

Good luck and happy gardening!

This column includes research-based information from land-grant universities around the country, including Alabama A&M and Auburn Universities. Email questions to Bethany@aces.edu or call 205- 612-9524. Like us on Facebook. Follow us on Twitter. The Alabama Cooperative Extension System (Alabama A&M University and Auburn University), is an equal opportunity educator and employer.