Tomatoes are cracking up after the recent rains, but growers are not amused. Recently, we’ve seen in an increase in the amount of tomato surface cracking. Tomato cracking is an abiotic disorder of tomato fruits that is associated with growing conditions. When tomatoes are left on the vine too long or during periods of rapid fruit growth, the tomato epidermis (or skin) does not have enough elasticity to compensate for the sudden growth. Eventually the skin splits and bursts. There are two main types of growth cracks 1) radial cracking, which is splitting of the skin from the stem scar towards the blossom end and 2) concentric cracking, which is splitting of the skin in a circular pattern around the stem. Radial cracks occur during humid, hot weather. Concentric cracks occur during rapid fruit growth associated with rainy weather following a period of dry weather. The earlier growth cracks occur during fruit development, the more damaging they are. Growth cracks can provide the perfect entry point for secondary fruit rotting organisms.
Photo: Debbie Roos
The most important means of controlling growth cracking is maintaining a steady, adequate supply of water or irrigation flow, especially during hot, dry conditions. Avoid over and under irrigating. Mulching also will help prevent dramatic fluctuations in soil moisture. Be especially wary if weather was cool and overcast followed by sunny, hot, and dry periods, and then high humidity and rainfall. Keeping foliage healthy and disease free is also critical. If the fruit lacks leaf cover, cracking can be more of a problem. Remove mature fruit right after heavy rains to prevent cracking. Follow recommendations from Cooperative Extension about plant nutrition, because high nitrogen and low levels of potassium can contribute to fruit cracking. Some varieties are more prone to cracking and can show cracking when the fruit are still green. Even varieties that show some resistance to cracking in the green stage may crack once the fruit starts turning red. Plum varieties like ‘Heinz’ and ‘Marglobe’ crack less than cherries and the larger fruited varieties like “Better Boy.” If you have a history of tomato cracking in your tomatoes, you may try switching to one of these varieties, ‘Daybreak’, ‘Jet Star’, ‘Pink Girl’, ‘Monte Carlo’, ‘Mountain Fresh’, ‘Mountain Spring’, and ‘Spitfire.’ New varieties are released regularly, so check with your local cooperative extension agent for latest variety recommendations for tomatoes. by: Emma Lookabaugh, Chris Gunter, and Barbara Shew
