Tomato Problems

Many of us have waited all summer to eat fresh tomatoes. Sometimes though, as the first tomatoes mature, we see that many may be deformed, cracked or somehow have problems. In this case, the weather, not microorganisms, is usually to blame. Four conditions are especially common locally. These include sunscald, cat-facing, cracking and blossom-end rot.

Sunscald appears on fruit as a white or yellow patch. It is usually found during hot, dry weather and is especially common when tomato plants are pruned and underlying fruit is suddenly exposed to the sun. There is no foolproof way to prevent sunscald. However, avoiding pruning in mid to late summer will help. Additionally, keep foliage as healthy as possible. Sunscald is also common on peppers.

Cat-facing is a condition that looks like something scratched and damaged the bottom surface of the tomato when it was young, and then the fruit scarred over and continue to heal. This condition is caused by extreme temperature fluctuations when the first tomatoes were set earlier in the season. The damaged area can be cut off, and the tomatoes are fine to eat. The condition usually disappears does not occur later in the season.

Cracking occurs when the skin of the tomato is not elastic enough to handle its growth rate. It can occur either horizontally or vertically on fruit. It is especially common with alternating periods of cool, wet weather and hot, dry weather. Additionally, it is common with faster growing plants with certain types such as heirloom purple colored varieties. Over fertilization and sporadic watering can also cause cracking. For prevention, keep tomatoes evenly moist to do not over fertilize. As with cat-facing, damage can be removed in the tomatoes can be eaten. Smaller tomatoes, such as grape and cherry tomatoes, seem to cracked glass often than larger varieties.

Blossom-end rot is usually caused by conditions that disrupt calcium uptake in the root zone of the plant, such as abnormally cool weather, irregular irrigation and infrequent summer rainstorms. The condition occurs at the bottom of the tomato (the blossom end) where a ‘dry rot' takes hold and the flesh develops a leathery feel and turns black or brown. More than half of an individual fruit may be affected. Blossom-end rot can be prevented by keeping the roots of the plant evenly moist. Allowing the soil around the roots to dry excessively after deeply irrigating can cause the rot. Mulch around plants helps keep water from evaporating from the soil too quickly and can prevent blossom-end rot. Various sprays labeled to prevent or mitigate the condition are available at garden centers but are not usually very effective in our climate. The best prevention is to irrigate correctly. Blossom-end rot can also occur in other plants, such as peppers and eggplants.