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Two Common Tomato Problems

Two Common Tomato Problems

By Therese Ciesinski, GardenSMART

At this time of year, two problems common to tomatoes frustrate home gardeners. One is blossom end rot and the other is fruit cracking. Both are caused by an inconsistent amount of water: not enough or too much, or more frequently, too little and then a deluge, either by rain or overwatering.

Unlike diseases that infect other parts of the plant, blossom end rot and cracking are especially frustrating because they affect the payoff: the fruit. Here are the specifics on each, and what you can do about them.

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Blossom End Rot

What it is: If your tomatoes have blossom end rot, you’ll know it. Ripe or unripe, the fruit will be black, water soaked, and sunken at the end where the flower was. The rot makes the fruit inedible.

What causes it: Although tomatoes are susceptible to many diseases, blossom end rot is not a disease. It’s a condition caused by a calcium deficiency. Once the condition occurs, fungus or bacteria cause the rotting. This deficiency occurs due to too much or not enough water, cool, rainy weather with high humidity or an imbalance of nutrients in the soil, especially the lack of calcium.

Prevention: Look for blossom end rot-resistant cultivars. Have your soil tested to make sure the pH and nutrient levels are where they need to be for successful tomato growing. Avoid using ammonia-based nitrogen fertilizers which compete with calcium uptake. Epsom salts can also compete with calcium uptake.

What to do: Be consistent with watering; if the weather has been dry, be sure to irrigate your plants before they become stressed. Don’t soak them and then let the soil get too dried out. Mulch plants to conserve soil moisture. Promptly remove any fruit showing symptoms.

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Photograph by Askepott5, CC BY-SA 4.0 <>, via Wikimedia Commons

Fruit Cracking

What it is: The skin of the tomato splits, exposing the inside of the fruit, which is then invaded by bacteria and fungus. The cracks be radial, starting at the stem end, or in concentric circles around the tomato. It can occur in green or red tomatoes. In fact, the longer a tomato remains on the vine the greater the chance of it cracking.

What causes it: A period of drought when the fruit is ripening, followed by an abundance of water (either by rain or irrigation). The rapid growth expands the interior of the fruit, splitting the skin. Excessively high temperatures can also cause cracking.

Prevention: When choosing seeds or plants, look for crack-resistant varieties. Plant in raised beds or areas with good drainage and no standing water. Don’t let ripe tomatoes stay on the vine for too long.

What to do: As with blossom end rot, consistent watering and mulch, i.e., not allowing plants to dry out, helps prevent the fruit from cracking. Tomatoes with cracks can be harvested and eaten as long as no rot has set in. Fruit with cracks will deteriorate quickly, so use ASAP. Black streaks, fuzz, oozing or a sour smell indicate rot, and the tomato should be thrown away.

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