Wednesday, Aug 27, 2014
Agri Leader

Vegetable diseases explored

Central Florida's Agri-Leader
Published:   |   Updated: March 11, 2013 at 07:57 PM

Growing your own vegetable garden is one of the most enjoyable aspects of living in the Sunshine State.

Tending to a garden allows us to get outside each day and enjoy the fruits of our labor once plants are ready for harvest. It can be quite disheartening, however, to find our precious plants wilted or ravaged by disease.

Although most vegetables are fairly easy to grow, we must be on guard for some damaging diseases common in our area. Here are a few diseases that are often seen on our most popular vegetables such as peppers, squash and tomatoes.

Fresh peppers are always a treat and are one of the most important commercially grown crops in the entire state. Home gardeners can enjoy jalapenos, pimentos and sweet bell peppers if they care for them properly.

Bacterial spot is one of the most problematic diseases for both home gardeners and commercial growers. A serious foliar disease, bacterial spot attacks plants most often when the weather is hot and rainy.

Most cases of bacterial spot in and around Polk County are seen from August through November. Because this disease strikes the foliage, any part of the plant that is above the soil line is susceptible. Within two to three days of infection, watery lesions develop on the surface of lower plant leaves. As the disease progresses, these lesions may turn brown, greasy and yellow.

Lesions eventually infect the fruit, causing raised pustules to appear, and fruit may be off-color. Peppers infected with bacterial spot will decay and are not edible. Planting certain cultivars may reduce your chances of finding bacterial spot in your garden. While Jupiter and Summer Sweet are especially vulnerable to this damaging bacterial disease, Early Calwonder is more resistant to it.

Squash is a staple in most Florida gardens. Our climate allows us to grow both summer and winter squash almost year-round. This vegetable is prone to a few diseases that can damage its vigor and affect the development of fruit.

Downy mildew produces symptoms such as yellow leaves, leaf spots and dark-colored masses of spores underneath plant leaves. Not only does downy mildew cause your plants to become unsightly, the fruit is usually tasteless once the plant is infected. You can reduce your chances of battling this disease by choosing resistant cultivars.

Another problem with squash in Florida is powdery mildew, which is named for the coating of fungi that looks like powdered sugar. This disease usually causes fruit to ripen too early, and most fruit is poor in quality. While powdery mildew is difficult to avoid in our growing area, you can reduce infection by choosing resistant cultivars. According to the University of Florida, powdery mildew is more common in the home garden than in commercial settings.

Nothing can replace a ripe, juicy tomato in a garden salad or on a sandwich. For this reason, tomatoes are one of the most commonly grown plants in Central Florida. Although there are a variety of diseases that attack tomatoes, some are more common in home gardens than others.

Bacterial spot strikes plants in warm, rainy weather conditions and is most often seen in August, September, October and November. Once infected, leaves turn brown with lesions that may have a yellow halo.

The fruit also suffers damage, as tomatoes affected with this disease typically develop brown spots on the fruit surface that appear scabbed over and raised. The appearance of the fruit is enough to discourage even the most voracious appetites, and home gardeners usually throw infected fruit away.

Another problematic disease in our growing area is Tomato Spotted Wilt Virus, or TSWV. Although many diseases begin in the soil, this disease is transmitted through thrips, which is a common garden pest. Tomato foliage is affected first, with brown speckled leaves that eventually wilt and die. Plant stems also are infected, and plants become stunted and eventually die. Weed control is the best way to reduce a thrips infestation and lower the chance of infection in your garden.

Monitor your plants regularly for signs of damaging diseases that may affect their health and vigor. Your local extension office may be able to offer advice on the treatment of these common Florida diseases. Sanitation, weed control and careful plant selection may be all you need to keep your plants healthy and producing delicious fruit.

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