Kelly Jackson
Christian County Extension Office
Fruit Cracking
Fruit cracking is a major physiological disorder that can cause significant damage to a wide variety to fruit including tomato, cherry, apple, pepper, peach, watermelon, and cantaloupe.
If you have ever went to pick a tomato and seen either concentric (as in concentric circles around the stem) or radial (radiating from the stem) cracks on the fruit, then you are seeing the effects of fruit cracking. If this occurs when the tomatoes are still green, they will likely rot on the vine before they ripen. In tomato, this is most likely to occur when heavy rainfall is preceded by dry weather. Tomatoes have a dense and fibrous root system that is very efficient in picking up water. So efficient, it seems, that when we have heavy rain it can quickly absorb an influx of water into the fruit causing it to crack. Rain is not the only factor however as some tomato cultivars are more susceptible or more resistant to cracking. The difference seems to be due to the pliability of the fruit skin rather than thickness. Jet Star, Mountain Fresh, Mountain Spring, Mountain Pride, Floralina and Sun Leaper are few cultivars proven to resist cracking in a study done by Kansas State University.
Cantaloupe, especially smooth-skinned types such as the canary melons, have also been known to crack. Temperature extremes between day and night, extreme soil moisture levels during ripening, close plant spacing, and very high or very low fertility rates are some of the reasons melons may crack. Some apple cultivars, including Stayman, Fuji, and Gala, may crack during the second half of their growing season especially in periods of high humidity following rains. The absorption of water through the fruit skin and that from the roots results in rapid enlargement of cells within the fruit and this pressure causes cracks in the skin. Not all the apples will show this symptom however and damage seems to appear mostly on those around the periphery of the tree canopy or fruit with higher sugar concentration. Similarly, cherry fruit will crack when the fruit absorbs extra water through the skin at the stem end or from excessive water being pulled into the fruit from the roots.
While we can’t control rainfall there are few things we can do to minimize problems. Most crops need around one inch of water per week to remain productive. Soaker hoses and drip irrigation systems are the best way for getting water to the roots and keeping the leaves dry to reduce diseases. Since cracking can sometimes be caused by dry weather followed by a rain, even consistent watering can reduce this problem. Mulching is also important as it helps regulate soil moisture. Selecting cultivars less prone to cracking is also recommended. However, keep in mind you can do everything right and still have problems with cracking in some years.
