Did You Know… Blossom End Rot Is Easy to Avoid

— Written By Nicole Sanchez and last updated by Pam Brylowe

Home Gardening Season is upon us, and for many, that means tomatoes. Tomatoes are both the best selling fresh vegetable at the grocery store and the best selling vegetable bedding plants purchased for home gardens. Blossom End Rot (BER) is an expression of nutrient deficiency, and is common in the sandy soils found in many parts of eastern NC. While most often associated with tomatoes, BER can also be found in other squash, and, less frequently, in peppers.

Blossom end rot is NOT a plant disease, though it is often treated as such in manuals and planting guides. It is actually a deficiency of calcium and is considered a physiological disorder. Calcium is not easily mobile in a plant, so its deficiency is expressed in the extremities of the plant, much the way frostbite and poor circulation in humans is first expressed in the fingers and toes.

So how is the home gardener to avoid BER? The answer lies in supplying the correct pH and consistent water to your crops. Our soils in Eastern NC tend to have lower pH (and are therefore more acidic) than is ideal for most vegetables. Most gardeners address low pH by adding lime, also known as calcium carbonate, to the soil. So if you have recently limed, there is likely enough calcium in your soil for your tomatoes, peppers, and squash. (If you need guidance on this, remember that soil test kits are available at your Extension office.) But here’s the kicker: just because the calcium is in the soil doesn’t mean the plant can access it. Consistent, adequate watering is key to keeping the calcium available to the plant’s root zone and keeping it mobile in the plant. Plants that get water stressed, such as drying out completely and wilting between waterings, are particularly prone to BER. So are over-fertilized plants that are growing too rapidly and have access to too much nitrogen.

Consistent watering is most important when the fruits are actually developing. There are sprays you can apply to the fruits, but BER is best addressed with proper pH and watering. Smaller fruited varieties, such as cherry tomatoes, are much less prone to BER. As a final note, calcium deficiency and inadequate water cause a myriad of symptoms in other vegetables, like internal browning in cabbage and tip burn on lettuces, or general poor performance. BER in tomatoes is distinct and easy to identify; in other vegetables, calcium deficiency looks similar to problems from other causes, and is difficult to distinguish from other issues. Because soils in our region tend to be acidic, home vegetable growers who are aware of their soil pH and watering practices will likely be more successful in their cultivation of many different vegetables.

North Carolina State University and North Carolina A&T State University commit themselves to positive action to secure equal opportunity regardless of race, color, creed, national origin, religion, sex, age, veteran status, or disability. In addition, the two Universities welcome all persons without regard to sexual orientation. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.

This article will be published in the Jones Post newspaper on May 9, 2013 and was written by Nicole Sanchez, Area Agent – Commercial Horticulture.