Issue link: http://read.dmtmag.com/i/675334
22 MAY 15, 2016 Good Fruit Grower www.goodfruit.com T hree German researchers have shed significant light on the process of fruit cracking in cherries. While researchers have known for many years the presence of too much water — either within cherries or cherry trees — results in cracking, little was known about the exact mechanism causing it until a few months ago. Moritz Knoche, Max Ossenbrink and Andreas Winkler of the Institute for Horticultural Production Systems at Leibniz-University, Hannover, believe they have identified a crucial link in the chain reaction leading to cracking. The culprit is malic acid, a naturally occurring compound imparting tartness to such fruit and vegeta- bles as apples, rhubarb, grapes and cherries. What led them to this conclusion? "We observe a surprising and dramatic increase in cracking when sweet cherry fruit are brought into direct contact with the expressed juice of sweet cherries," they wrote in an article published in the July 2015 issue of the Journal of the American Society for Horticultural Science. Sweet cherry juice caused rapid fruit cracking when water intake was limited. Cracking also occurred when cherries were placed in an artificial juice made of the majority of compounds normally passing through its cell walls as the fruit matures. Proof came when cracking occurred at a very high rate when cherries were placed in a solution made only of malic acid. Trail of evidence In 2014, Knoche found what he called "a surprisingly low turgor in Stage III sweet cherries." Turgor refers to the amount of pressure pushing against the plasma Researchers crack the case on why cherries crack Cherries Too much water is a known cause of cherry cracking, but malic acid is a newly identified culprit. by Dave Weinstock