Good Fruit Grower

May 15

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Cherries Cherry cracking TEST by Melissa Hansen T he Washington Tree Fruit Research Commission has developed a simple test for growers to determine the susceptibility of their cherries to rain cracking. All that's needed are around 50 randomly collected cherries from trees, distilled water, a large pan, and two hours of time. Through years of study to find effective antisplitting materials for cherries, Dr. Ines Hanrahan has learned that cracking susceptibility varies from year to year, by variety, and changes during the growing season. Although she continues her trials on anticracking agents, she's yet to find a material completely eliminating cherry splitting induced by rain. However, in many cases, she says the material can make the difference between a crop that can be harvested profitably and one that is a complete loss. Hanrahan has perfected a test for growers to use in determining the cracking susceptibility of different blocks of fruit in real time. "If you know you're susceptible, then you can decide if it's cost effective to try to prevent the cracking," she said earlier to the Good Fruit Grower. Some materials require —Ines Hanrahan weekly applications for a month before harvest when fruit may not be susceptible. Four applications can be costly and time consuming, Hanrahan said. "If you know you're susceptible, then you can decide if it's cost effective to try to prevent the cracking." Steps for cracking test 1. Randomly sample five healthy cherries from each of ten typical trees early in the morning (50 fruit total). 2. Within one to two hours of picking, fully submerge fruit for two hours in distilled water at room temperature (a disposable, large aluminum pan works well). 3. Count cracked fruit. Cracking index 0 cracked fruit: The block is not susceptible to cracking. Rain protection is not recommended. 1 to 5 cracked fruit: The block is becoming susceptible. Rain protection is recommended, especially if rain is forecast. More than 5 cracked fruit (10% of sample or greater): The block is highly susceptible. Rain protection is strongly recommended. If reusing the pan, be sure to rinse with distilled water and air dry. Washing the pan with soap and tap water will leave trace ionic residues and change how the fruit cracks. • GOOD FRUIT GROWER May 15, 2013 31

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