Summer is a great time of year to be a gardener as bright sunshine and warm days encourage plant growth and development, but it’ also the time of year that Extension offices get an increase in calls about plant diseases and pest problems. One of the most common problems I hear about is called blossom end rot, which is commonly found on tomato, but can also occur on pepper, eggplant, and squash. This disorder can completely destroy the fruit of a plant, rendering it useless to the consumer, so it’s important to understand what it is and how to manage it if you suspect it’s a problem in your garden.
Blossom end rot most often occurs on the first fruits formed by plants, and usually occurs more often on plants grown in pots. It will initially look like small bruises or water-soaked spots on the blossom ends of the fruit, which enlarge, become sunken and leathery, and turn a dark brown to black color. Occasionally there will not be any visual evidence of the disorder on the outside of the fruit, but the interior will be discolored and shrunken. Usually, if the spot is small enough, you can simply trim it off and consume the fruit as you normally would.
There is some good news if you suspect blossom end rot to be an issue in your garden- it is not caused by a disease or pest! Instead, blossom end rot is caused by calcium deficiency in the plants. A calcium deficiency can occur for a number of reasons. It could be that there is an issue with the soil itself- such as improper soil pH or low calcium levels in the soil. It is critical as a gardener that you soil test regularly in order to correct soil pH and fertility issues before they cause problems with plant growth. The other possible cause of calcium deficiency is an inability for the plants to absorb and transport calcium from the soil to their fruit. Root damage can cause plants to be unable to absorb nutrients and water, but drought stress, fluctuations in soil moisture, and weather conditions that limit transpiration can also reduce calcium uptake in the plant.
If you’re having trouble with blossom end rot, there are a few things you can consider doing to help manage and prevent it. First, select cultivars of vegetables that are tolerant of calcium deficiencies and less susceptible to blossom end rot problems. Remember to soil test and make corrections to soil pH and fertility as directed by your soil test report. It’s important to note that over-fertilizing is not the solution to blossom end rot- having too much nitrogen in the soil will actually cause the plant to grow more leaves, which tend to pull calcium away from fruit, making the problem worse. Finally, one of the biggest causes of calcium deficiency is inconsistency in watering. During wet periods, be sure that you have adequate drainage in your soil and that the soil is able to dry out. In dry periods, be sure to water consistently and evenly, and use mulch to help retain soil moisture. A good rule of thumb is that most plants need approximately 1 inch of water each week.
If you suspect you have blossom end rot issues, or if you need help identifying a pest or disease in your garden, let us know at uge3181@uga.edu or 706-359-3233.
