Sweet Cherry Cracking
Another aspect of Dr. Schrader's program is to provide growers with a means to protect sweet cherries from cracking or splitting during or after rain. Rain events can be devastating to a cherry crop (Fig.7). When more than 25% of the cherries crack, labor costs for sorting out split cherries usually exceed the value of the crop. Two causes of this cracking phenomenon have been identified. Most cracking occurs as a result of direct water absorption through the fruit skin or cuticle. High relative humidity around the fruit and warmer fruit temperatures enhance water absorption by cherries. The second cause is water supplied to the fruit through the trees's vascular system.
RainGard® (U.S. Patent No. 7,222,455) was invented in Schrader's laboratory as a cherry protectant and became commercially available in 2007. The concept was to coat the fruit with a protective covering to slow water absorption and decrease cracking. A program of applying three to four applications of RainGard® prior to harvest has reduced cracking losses up to 50%. Because of the high values of cherries, the use of RainGard® to reduce cracking in rain-induced events serves as inexpensive insurance. Its use can potentially save growers millions of dollars each year and in some years make the difference between harvesting a crop or losing it entirely.
Fig. 7. Rain cracking of 'Bing' sweet cherries.
Larry Schrader, Horticulturist/Plant Physiologist
Tree Fruit Research & Extension Center, Wenatchee
Office Ph: 509-663-8181 x265
Office Hours: by appointment