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Common Tomato Disorders

When you harvest your tomatoes they don’t all have that “Perfect 10” look. Some of the misshapen fruit is caused by a physiological disorder (environmental stress – too hot, too cold, too dry, and too wet).

One of the more common disorders is blossom-end rot (BER). The blossom-end, as opposed to the stem end, is characterized by a large, leathery brown or black spot. BER is caused by a lack of calcium in the fruit which causes cells to collapse. Fluctuating soil moisture will also cause BER. Make sure your calcium levels in the soil are adequate (soil test) and you mulch your plants to stabilize the soil moisture. Calcium sprays are worthless, since movement of calcium into the fruit is inadequate to correct calcium deficiencies. Some varieties are less susceptible to BER, so select accordingly.

Catface: Severe scarring on the blossom end of the fruit giving the appearance of a cat’s face. If temperatures are in the 50 degree F. range during flowering, catface can occur. Consequently, the disorder is more prevalent on the first fruits formed.

Fruit Cracking: Heavy rain or heavy watering will cause rapid uptake of water by the fruit resulting in fruit cracking. Crack resistant varieties are available. Also maintain uniform soil moisture by mulching and steady watering.

Yellow or Green Shoulders: The tops of the fruit never ripen completely. This is a genetic problem that can be eliminated by growing plants with uniform ripening genes. Most seed catalogs will say in the variety descriptions, if it is prone to this problem.

Sun Scald: Yellowish to white water soaked areas appears on the fruit exposed to the sun. Keep the plants well fertilized, so leaves shade the fruit. Also, don’t prune plants late in the season after the fruit has formed.

For more information contact George McVey, Program Assistant, Horticulture and Union County Master Gardener Coordinator at 937.644.8117 or toll free for Union County Residents 800.859.8584 or e-mail him at gmcvey@ag.osu.edu.