Managing Sunscald on Vegetables

Sunscalded vegetable

With hot, dry days comes many problems for many home gardeners across the state. As moisture levels become inconsistent, blossom end rot becomes a situation for tomatoes, peppers and even watermelons. With an increased need for water, overhead watering can increase disease and other pest problems. And lastly, the sun & heat can cause damage on fruit and vegetables.

While all of our summer vegetables are heat loving plants, there is such a thing as too much heat. Peppers, tomatoes and some tree fruit are especially vulnerable to sun scald, a condition that can cause fruit and vegetables to be both aesthetically and physically damaged. This damage generally occurs in late summer, but we are experiencing this problem earlier than normal this year due to the high humidity and temperatures.

Sunscald is common on pepper and tomatoes and is the result of overexposure to bright and direct sunlight. We all know that these plants require over 6 hours of sun a day to be productive, but what we may not always take into account is the need to cover the fruit to protect them from too much sun. Excess light can cause the fruit to become woody, tough, and even increase the chance of rot. Damaged areas on fruit can range from light, tough tissue to sunken and leathery spots on the fruit. These areas can be entry points for fungus and bacteria, allowing the fruit to rot. While the damage does not ruin fruit, most often the area can be pared off and the rest of the fruit can be eaten, there is the potential that rot can set in and the sunscald can make the fruit and vegetables subpar for the market.

Sunscald can be prevented by ensuring that there is plenty of leaf cover on the plant to shade the fruit from light. Many people that prune plants, especially tomatoes, are likely to see sunscald, along with those that do not fertilize or have disease problems. For those that prefer to prune tomatoes, remember that you need plenty of leaves, not only for shading the tomatoes, but also for production of sugars through photosynthesis. These sugars are needed to make the fruits sweet, juicy and delicious. Poor fertility can lead to a lack of leaves, so it is important to fertilize LIGHTLY throughout the season to ensure that the tomato can stay healthy and vigorous. Remember that too much fertilizer, especially Nitrogen, can lead to large, healthy plants with lots of leaves but no fruit, so there is a fine balance to be kept. Diseases like Early Blight, Septoria Leaf Spot and Bacterial Spot can exasperate the situation, causing damaged and diseased leaves to fall of prematurely, exposing the fruits to harsh light. Lastly, and most importantly, maintain constant moisture levels throughout the season to make sure that you have happy and healthy plants. Other methods of prevention include planting sunscald resistant plants, especially bell peppers, and using row covers to shade plants in the heat of the day.

As with most problems that occur in the garden, being aware and on top of things can help with most situations. Catching diseases or physiological disorders early can be the difference in a great harvest or one that leaves you wanting more. For more information about sunscald or other gardening topics, contact your local Extension Office.

Sunscald on tomatoes and peppers can be a common problem for home gardeners and commercial producers alike. Picture compliments of Beacon Ranch, Douglas Alabama.

Garden Talk is written by Hunter McBrayer, Urban Regional Extension Agent, of the Alabama Cooperative Extension System (ACES). He is housed at the Marshall County Extension Office, which is based at the Marshall County Courthouse in Guntersville, AL. This column includes research based information from land-grant universities around the country, including Alabama A&M and Auburn Universities. Email questions to Hunter at rhm0015@aces.edu or call (256) 582-2009.

ACES (Alabama A&M University and Auburn University) is committed to affirmative action, equal opportunity and the diversity of its workforce.  Educational programs serve all people regardless of race, color, national origin, age, disability, sex, gender identity.