Tomatoes were once believed to be poisonous and avoided at all costs. Today, they are one of the most popular plants grown in home gardens, appearing in more than 86 percent of gardens across the United States. Whether sliced fresh for sandwiches or turned into salsa and sauce, tomatoes are a garden favorite. Unfortunately, they can also come with a few common diseases and problems. The good news is that with a little attention and proper care, tomatoes can thrive throughout the growing season.
One of the most common tomato diseases is early blight. This fungal disease lives in the soil and is often spread when rain or overhead irrigation splashes soil onto the lower leaves of the plant. Symptoms usually begin as dark spots on the lower leaves, followed by yellowing and browning of the foliage. Over time, the infection can spread upward through the plant and cause significant leaf loss.
Fortunately, there are several ways to reduce the risk of early blight. Avoid overhead watering whenever possible and instead water near the base of the plant. Applying mulch around tomatoes helps prevent soil from splashing onto the leaves and also helps conserve soil moisture. Caging or staking tomatoes improves air circulation and keeps foliage off the ground, reducing the spread of disease.
Good sanitation is also important. Tomato cages should be cleaned at the end of each season because fungal spores can survive on plant debris. If lower leaves begin showing symptoms, remove them promptly to help slow the spread of infection. Severely infected plants should be removed and thrown away rather than added to the compost pile. Rotating where tomatoes are planted each year and selecting disease-resistant varieties can also help reduce problems.
Fungicides labeled for tomatoes may help slow or prevent early blight when used according to label directions. Applications are most effective when started early and repeated regularly throughout the season.
Another common tomato issue is blossom end rot. This problem causes dark, sunken spots on the blossom end of tomatoes and can also affect peppers, squash, cucumbers, and eggplant. While many people assume it is caused by a lack of calcium in the soil, the real issue is often inconsistent watering.
During periods of rapid growth, hot weather, or moisture stress, plants may struggle to move calcium into the developing fruit. As a result, the blossom end of the fruit breaks down and rots.
Maintaining even soil moisture is the best way to prevent blossom end rot. Mulching around plants can help regulate soil moisture and reduce stress on the plant. Avoid over-fertilizing, especially with high nitrogen fertilizers that encourage excessive leafy growth.
Despite popular gardening myths, adding Epsom salts or calcium sprays usually does not solve the problem. Affected fruit can be removed, and if only a small portion is damaged, the healthy part of the tomato is still safe to eat.
Another tomato problem that often worries gardeners is leaf roll. Fortunately, this condition is usually temporary and is not caused by a disease or insect.
Leaf roll occurs when tomato plants grow rapidly during cool, moist conditions and then experience sudden heat, heavy rain, or other environmental stress. The leaves curl upward as the plant tries to conserve moisture and balance growth between the roots and foliage.
Excessive soil moisture can also contribute to leaf roll because saturated soils reduce oxygen around the roots. To help avoid this problem, water consistently, avoid overwatering, and mulch around plants to moderate soil moisture levels. Avoid deep cultivation near tomato roots, as root disturbance can also trigger leaf rolling.
The good news is that most healthy tomato plants recover from leaf roll once growing conditions stabilize.
Tomatoes continue to be one of the most rewarding crops for home gardeners. By recognizing common problems early and using good gardening practices, you can keep plants healthy and enjoy a productive harvest all season long.
Elizabeth Exstrom is a Horticulture Extension Educator with Nebraska Extension in Hall County. For research-based gardening information, contact Elizabeth at elizabeth.exstrom@unl.edu, visit huskerhort.com, or follow HuskerHort on Facebook and Twitter.