While Florida has nine months of good vegetable gardening weather, the Sunshine State offers the home gardener a few challenges, and one of them is growing tomatoes in the humid environment. When the weather is cool and wet, usually from December until May, the tomato will battle against fungus. There are a few tricks to help make tomato growing more successful in Florida.
Fungus Among Us
Anthracnose, sclerotinia stem rot, septoria leaf rot, gray mold, fusarium wilt, verticillium wilt, bacterial wilt, leaf mold, late blight and early blight are tomato fungal diseases. Each causes the plant to lose vigor. Plants will appear to have spots on leaves or fruit, stems may become rotten and fruit can have lesions that become soft and watery. Cool and rainy weather brings out the worst of Florida tomato fungus. The spores will coat the plant and multiply rapidly.
What to Do
Choose healthy tomato seedlings of a disease-resistant variety. Avoid water on the leaves and do not touch them when wet as this will spread fungal spores. Mulching with pine bark, wood shavings, straw or plastic will keep soil from splashing onto the leaves when rains come and reduces the incidence of soil-borne diseases. Tie plants to a trellis for support and to keep leaves and fruit from touching the ground. Planting in a different location each year is a good idea.
There isn't a single fungicide product that can control all fungal types. The University of Florida's IFAS Plant Pathology Department has compiled a chart that lists the fungicide, the rate of application, and the type of pathogens that it will eradicate. Identifying the type of fungus, using the correct fungicide, and following directions precisely from the label will keep pollution to a minimum.
A home gardener's best choice may be to eradicate the diseased plant and start with new seedlings of a disease-resistant variety. Labels that indicate F1 (fusarium), TSWV (tomato spotted wilt virus) are resistant types. Heirlooms are generally less disease-resistant to Florida fungus attacks.
Serious growers are now using high-tunnel greenhouses to keep rain from falling on leaves, and to ensure nutrients aren't being diluted. Good air flow is a must as temperature and humidity can be very high in a greenhouse, which causes fungus to proliferate. Large air-circulating fans are used to keep leaves dry and to lower the humidity.