Pensacola News Journal

For: Saturday, June 23, 2001

By: Daniel E. Mullins

Extension Horticultural Agent

Santa Rosa County

Rains Return – Watch for Changes in the Landscape

Timely rainfall cures many gardening ailments and rains over the past couple of weeks are sure to help invigorate lawns, flowers and vegetable gardens. This brings up the question: Why does a good rain seem to do more good than my irrigation efforts?

There are several reasons for this. First, we often think that we are applying plenty of water each time that we irrigate, but this might not be the case. Also, we could be delivering the water faster than it can be taken up by the soil. A good, slow, soaking rain on the other hand, more uniformly soaks the soil.

The “can or pan test” has been done to death in this space, but it remains a good way of determining if the necessary ½ to ¾ of an inch of water is being applied at each irrigation.

Another reason that a rain seems to refresh plants has to do with the stabilizing effect of cooler temperatures and higher humidity. During rains and the associated cloudy weather plants have an opportunity to slow down, take up water and rest for a few hours.

Plants also seem to look greener after a rainy period. My maternal grandfather was a farmer, and a favorite quote of his was: “God’s water is better than ours.” He was obviously speaking of how the color of crops improved following a rain versus being irrigated.

My granddad was right. Rain water contains nitrogen that is fixed by lightning. The greener, more crisp appearance of plants after a shower is therefore not an optical illusion. Rainfall supplies more than just water.

Mid-Season Tomato Growing Tips

This has been a good tomato growing season to date. The dry weather and associated low humidity has resulted in less infection by the fungi that cause leaf blights and fruit rots. As of early June, plants have loaded up with fruit.

Don’t slack off on maintenance. Good care over the next few weeks can help to ensure long term picking and enjoyment.

Pest control is key to an extended harvest season. There are several fungus diseases and insects that can literally ruin the crop, if unchecked.

There are several practices that will help to reduce the incidence of leaf blights and fruit rots. First, irrigate during the cooler times of the day without wetting the leaves and stems. Don’t harvest, handle plants or even walk through the tomato patch when the leaves are wet. Fungicides can prevent infection if applications are begun before significant damage is evident. Recommended products include maneb, mancozeb and chlorathalonil. A more complete disease preventative spray can be prepared by mixing basic copper sulfate with either maneb or mancozeb. Follow label directions carefully.

There are two species of caterpillars that can also cause severe fruit damage during mid to late season. The tomato fruitworm, which is the same as the corn earworm and cotton bollworm, bores into the fruit. Tomato hornworm is that giant green caterpillar that can strip the leaves from a plant within a few days.

Both caterpillar species can be controlled with insecticides if treatment is begun when they are relatively small. B.t. (Bacillus thuringiensis) is a biological control product that is effective on many caterpillars. It is sold under several trade names such as Dipel, Biotrol and Thuricide. A spray containing carbaryl, often sold as Sevin, is also recommended.

Should normal rainfall patterns return, which in our area means frequent afternoon thundershowers, the potential for attack by pests will increase suddenly. Stay alert and protect those home grown tomatoes!