These studies will be continued to determine the long term effects of multiple oil applications each season for several years. Factors Causing Sunburn in Apple Sunburn or sunscald causes multi-million dollar losses annually to apple growers. Fruit on young apple trees in high density plantings is especially vulnerable. All three practices reduce sunburn, but all are expensive and the long term consequences of using these practices are not understood. Moreover, neither the specific environmental conditions that induce sunburn nor the physiological changes that occur in the fruit during sunburn are understood.
Studies are in progress to determine the importance of each type of injury in apples.
These findings will be confirmed during 1997. As the factors causing sunburn are elucidated, existing technology will be refined to minimize sunburn and more permanent solutions to the sunburn problem through genetic selections will be pursued. Washington State University Tree Fruit Research and Extension Center 1100 N. Western Ave.