Pensacola News Journal

For: Saturday, May 18, 2002

By: Daniel E. Mullins

Extension Horticulture Agent

Santa Rosa County

When Rains Return, Gardening Practices Should Change

Dry weather is the dominant subject of gardening conversations these days. Several weeks have passed since we have had a good, slow, soaking rain throughout the coastal South. Though it has been necessary to pay close attention to irrigation practices, the recent clear weather and relatively low humidity has resulted in fewer plant disease problems.

Conditions that favor many plant diseases are soon to arrive. High temperatures, frequent showers and high humidity are conditions that make the plant parasitic fungi thrive.

Gardeners should be ready to change some cultural practices when wet weather returns. There are a few simple things that can be done to lower the incidence of disease in the landscape.

First, don’t irrigate if rainfall is providing adequate soil moisture. The less frequent that plant stems and leaves are wetted, the lower the incidence of fungal diseases. In fact, many of the common diseases require that a film of water be present for several hours before the spores can infect.

This is the reason that we recommend deep, but infrequent watering of lawns, flowers, vegetables and shrubs. The best time to water is during the early morning hours because stems and leaves will dry off quickly as temperatures rise.

Mulch the surface of flower and vegetable beds by applying a 2 to 3 inch layer of coarse material such as bark, leaves or pine needles. Mulch is well known to conserve soil moisture, suppress weeds and moderate soil temperatures, but too little is said about its ability to control diseases.

Some diseases start on herbaceous plants by being carried in splashing soil. Heavy rains, when falling upon bare soil can move soil particles, and disease, up to 2 feet high on plant stems and leaves. When mulch is present, it reduces the impact of raindrops and prevents muddy water from splashing.

Increase the air flow around plants by removing low hanging branches and properly spacing flower and vegetable plants. Crowded plants remain wet longer, resulting in greater disease pressure. If this means removing a few that are crowding their neighbors, your plants will probably be more healthy in the long term.

The application of fungicides might be necessary in some cases. I know for example, that there have been fewer tomato plants and flowering bedding plants affected with leaf spot diseases this spring. Obviously, this is due to dry weather and the associated lower than normal humidity. If frequent showers begin to occur soon, this condition can change in a hurry.

There are new fungicides on the market that are replacing some of the older, more familiar products. Contact your Extension office or garden and landscape professional for specific recommendations, if needed.

Question of the Week: My squash plants appear to be healthy, but the young fruit won’t grow. They shrivel and eventually die. Is this a disease and if so, what can I do?

Answer: The squash are not being pollinated properly, probably due to a lack of sufficient honey bees in your area. Squash have male and female flowers, but in different places on the vine. The “squash” that first appears with a blossom on the end, is actually an unfertilized ovary. It can’t develop until sufficient pollen is moved from the male flowers by pollinating insects – primarily bees.

Short of becoming a beekeeper or hoping that some bees will eventually find your garden, try moving some pollen using a small, soft brush. Early in the morning, brush the inside of male flowers and transfer the pollen to the female bloom. In the center of the flower you will find a sticky, somewhat shiny area. That is the female receptacle, and is your target for placing the pollen.