Pensacola News Journal

For: Saturday, May 1, 2004

By: Daniel E. Mullins

Extension Horticulture Agent

Santa Rosa County

Fine Tune Your Tomato Growing for an Extended Harvest Season

The tomato is the number one vegetable grown in home gardens, and most area gardeners establish plants each spring. The hope for home grown taste produces an urge to grow tomatoes even among those who otherwise prefer to spend most gardening time with the lawn, flowers and other ornamental plantings.

I have noted varying degrees of success among tomato growers. Some years it seems that everyone can produce them, while during other years home grown tomatoes are scarce.

It would be easy to blame our hot, muggy summer weather when tomato production is down. It’s true that extremely high temperatures and frequent summer rains can reduce fruit set and otherwise shorten the harvest season. On the other hand, these environmental conditions should be expected and there are some cultural practices that help to ensure more consistent tomato production each year.

The spring tomato plants should have already been established, so we will dispense with the usual suggestions concerning plant selection, soil preparation and planting. For the remainder of the season success depends upon proper watering, fertilization and pest control.

■ Watering: Once plants are established, it is important to irrigate thoroughly and deeply enough to prevent moisture stress while young plants are developing. Daily watering is generally not required until plants begin fruit set and development, though this practice might be necessary where plants are being grown in extremely sandy soil or in containers.

Once fruit is present and begins to enlarge, the demand for soil moisture increases dramatically. If the soil is allowed to become very dry at this time, blossom-end rot and other long term problems often occur.

Though there might be a need to water the soil daily when plants are heavily loaded with fruit, this practice should be done with care. The water should be delivered slowly and without wetting the leaves, stems or fruit. Each time the upper parts of tomato plants are wetted, there is more chance to encounter leaf and stem blights as well as fruit rots. The use of soaker hoses or careful hand watering is suggested for delivering the water to the soil.

Fertilization: Light, supplemental applications of fertilizer are generally needed to grow a vigorous, healthy plant that will have the ability to produce much fruit. Growers who use a slow release product might not need to re-apply fertilizer.

There is however, too much of a good thing when fertilizing tomatoes. The objective should be to fertilize just enough to produce a sizeable healthy plant and then lower the rate or cease fertilizing once a good crop of fruit is on the plant. Continuing to maintain a high soil nitrogen level far into the season can actually have a negative effect by keeping plants too lush and reducing fruit set.

Pest Control: Here is where most producers of home grown tomatoes drop the ball. By the time that fruit is present, we are usually into our Gulf Coast’s wettest season and the time that the potential for blights and insect damage is greatest. Unless the plants and developing fruit is protected from these diseases and insects only a couple of “pickings” can be expected. Well kept plants have the ability to produce for weeks.

Pest control practices include the regular application of an approved fungicide that is labeled for the control of early and late blight of tomato. Maneb® and Mancozeb® are two such products. Copper based fungicides help and organic gardeners might consider these as an alternative. The irrigation practice recommended above also helps to reduce the incidence of disease and coarse mulches of leaves or bark at the base of plants reduces the possibility of fungal spores being splashed and contacting the foliage.

Some insects can be controlled with insecticidal soap applications, while caterpillars such as tomato horn worm and fruit worm can be controlled with the biological product known as Bacillus thuriengensis. It is sold under several trade names including Dipel®, Biotrol®, and Thuricide®. Follow label directions carefully when using these and other pest control products.