Everyone loves mouthwatering homegrown tomatoes, but too often gardeners are disappointed when their crop develops problems. Here's a quick rundown of common tomato ailments and how to treat them.
Symptoms: Blossom end rot occurs when a sunken rotten spot appears on the bottom end of the fruit.
Causes: Blossom end rot is caused by a lack of calcium, resulting in the tissues at the end of the fruit breaking down. A shortage of calcium can develop if the soil is low on the chemical or if the calcium in the soil is tied up due to low soil pH. It also could be due to inconsistent watering or drought that limits how much calcium is absorbed by the plant.
Solutions: Start with a soil test. If your soil has low pH you might need to add lime to the garden. The best pH for tomatoes should be between 6.5 and 6.8.
Also, mulch your plants to maintain consistent soil moisture. Vegetables require 1 to 1-1/2 inches of water a week, so use a soaker hose to deliver water directly to the root zones of the plants. And finally, don't overfeed your plants. Fertilizers with high nitrogen content bind the calcium in the soil, making it impossible for the plant to absorb.
Symptoms: Cracking occurs when the skin of mature or nearly mature tomatoes splits either in concentric circles or radially down the side of the fruit. The fruit remains edible, but the cracked portion of the tomato must be cut away. Insects also can attack the fruit through the cracks.
Causes: Some varieties of tomatoes are more susceptible to cracking than others. Cracking occurs when the plants have periods of very fast growth followed by slow growth and then fast again. The cells in the tomatoes skin can't stretch fast enough and cracking occurs. Dry periods followed by heavy irrigation or rainfall is one of the main causes of cracking.
Solutions: Mulch tomato plants to encourage consistent soil moisture. Also, do not over fertilize the plants to encourage fast growth. When selecting tomato varieties look for those that are listed as crack resistant.
Symptoms: Plants suffering from tobacco mosaic virus have mottled foliage with alternating yellow and green areas. The green areas also might be raised or blistered. The fruit will also be misshapen with patches of lighter areas over the skin.
Cause: Tobacco mosaic is generally transmitted by humans who have had contact with tobacco products or by insects that have been feeding on tobacco plants. When a tomato is handled during planting or harvesting, an open wound occurs that allows the virus to pass into the plant.
Solutions: If you smoke, always wash your hands thoroughly before you touch tomato plants. There is no cure for tobacco mosaic, so remove plants immediately if symptoms appear. Avoid planting tomatoes in the same location year after year. Destroy infected plants because research shows that the virus can live in dead plants for up to 50 years.
Symptoms: A serious disease, anthracnose can be identified by small lesions, sunken areas, or black spots on the ripe fruit or foliage of the tomato. It can spread quickly and infect an entire patch of tomatoes.
Cause: Anthracnose can be found in the soil, seeds, weeds, and infected plant debris. It's most common in warm, humid climates and is spread by rain and irrigation that splashes on the foliage.
Solutions: Once infected, plants should be removed completely from the garden. Mulch plants to keep the foliage dry and keep your garden as weed free as possible. Do not use overhead sprinklers, and rotate crops every few years to prevent the disease from infecting the soil.
Symptoms: There are two major types of tomato wilt: fusarium and verticillium. Both are fungal diseases that cause the foliage of the plants to wilt, turn yellow, and die. Sometimes the plants survive but remain stunted and deformed.
Causes: Both diseases are caused by a fungus that enters the plant through the roots and then blocks the water supply to the leaves.
Solutions: Rotate tomato plants to another section of the garden if either one of these diseases strike. It takes 4-6 years for the fungi to disappear from the soil. Keep garden beds as weed-free as possible, and fertilize to promote healthy, vigorous tomato plants. Most important, plant disease-resistant varieties. Select varieties with an F (for fusarium) and/or a V (for verticillium) after their names.
Symptoms: There are three major blights that attack tomatoes: early blight, late blight, and septoria leaf spot. All three are fungal diseases that result in spotted leaves or wilted leaves. Early blight appears on lower leaves after a heavy fruit set. Spots on the foliage are dark brown to black with a yellow bull's-eye. They eventually fall off the plant. Late blight happens when the weather is warm during the day but cool at night. Spots on the leaves are dark green to black. The fruits also might develop spots. Septoria leaf spot appears on the lower leaves of the plant after the first fruits appear. The foliage eventually drops off the plant, leaving the fruit exposed to sunscald.
Causes: All three diseases are spread by spores that splash on the plants' foliage during rainy or wet weather.
Solutions: These diseases spread rapidly and are hard to control once the plants are infected. To keep plants healthy, rotate tomato crops every few years so spores don't build up in the soil. Also, mulch your plants to keep soil from splashing on the leaves during downpours. To irrigate, use a soaker hose or drip irrigation placed underneath the mulch. It also helps to plant disease-resistant varieties.