Keep it Green, by Michael Womack
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Saturday, June 2, 2001
Help protect your delicate tomatoes as they ripen
The number one vegetable in backyard gardens is tomatoes. We grow them and share pounds of produce with our family and friends. However, many people start seeing problems with their tomatoes as fruit starts to set and matures.
Many common problems associated with tomatoes relate directly to water relations. It is important that tomatoes have a constant supply of water once fruit is formed. Lack of water can cause a variety of problems including blossom end rot, cat-facing, and growth cracks.
Blossom end rot looks exactly like you might expect by its name. It is characterized by round, water-soaked spots on the bottom or blossom end of the fruit. As the tomato is under water stress, the plant compensates by drawing water for essential plant functions from "luxury" areas. One of the first sources is the fruit. Water is drawn from the furthest point of the fruit, the blossom end.
To prevent blossom end rot, keep the soil moisture uniform; mulching will help to conserve water. Also avoid high nitrogen fertilizers or large quantities of fresh manure. Also avoid cultivating deeper than 1 inch within a one foot radius of the plant. Damaging the root system will affect water availability.
Catfacing is another water related problem. It is noted for greenish tan streaks and bands of scar tissue which mar the blossom end of the fruit, resulting in malformed, scarred and puckered tomatoes.
Catfacing most often occurs when water availability is not uniform; however, it can also occur in extreme heat (above 85 degrees F) or cold (below 55 degrees F). It also may be the result of herbicide sprays.
A similar problem is cracking. Cracking occurs when conditions change allowing rapid growth during fruit maturation. Overwatering or heavy rain following a dry period. Tomatoes are most susceptible to cracking after they have reached full size and begin to change color. Cracking also becomes more common in hot weather.
Cracked tomatoes, like catfaced fruit are still edible. Shallow cracks frequently heal over, but may rupture when fruit is handled roughly during harvest. Deep cracks may allow decay organisms to enter the fruit and promote fruit rots.
Other problems we see are related to insects, primarily leaf-footed bugs and green squash bugs, both of which are commonly referred to as brown and green stink bugs respectively. These insects will leave little yellow marks on your tomatoes where they have inserted their proboscis, the sucking part of their mouth, into your luscious, ripening fruit. The spots are often a bit tough, but the fruit are still edible. Unfortunately, there's not much you can do to keep the insects off; however, you can pick your tomatoes when they are first changing colors allowing them to ripen inside, safe from these pests.
Another insect pest that might put a damper on your tomato harvest is the spider mite. These tiny creatures live on the underside of your tomato leaves, sucking sap from the plant. They create a brassy golden look on the upper side of the leaf and my have small webs on the underside. Spider mites are very difficult to control once they attack vegetables. If the infestation is extensive, you might have to pull up the plant to prevent the spread of the insect to other plants. If you do try to take a chemical approach, make sure any insecticide you use is labeled for both the insect and plant being attacked.
If you notice that your plants are not putting on new fruit, don't worry. Tomatoes are heat sensitive. As night temperatures increase, you tomato plants will likely stop setting new fruit, even if you use blossom set products. Some varieties such as Surefire and Merced are less heat sensitive and are thus better varieties for spring gardens in South Texas.
When your tomatoes stop producing, most people pull them up and replant in the fall to get new, vigorous growth that is free of insect and disease problems. However, if your plants survive the heat of the summer, they will likely start producing again in the fall as temperatures start to drop.
Keeping an eye out for these potential tomato tragedies will help you get the most out of your harvest. Watering evenly and regularly and not letting insects get the upper hand will go a long way to nip these problems in the bud. With these tips in mind you should be able to increase your harvest and have plenty for your family, friends and neighbors.
Michael Womack is a horticulturist with the Texas Agricultural Extension Service. Got a question? Michael Womack will answer landscape and gardening questions. Call 886-4648, category 3025 to record your question. Write Keep It Green, Corpus Christi Caller-Times, P.O. Box 9136, Corpus Christi, TX 78469 or email wm-womack@tamu.edu
2000 Caller-Times Publishing
Company, a Scripps Howard newspaper. All
rights reserved.
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