Thinning with fats: lipids can be effective thinning agents in conventional and organic tree fruit production

摘要

Chemical thinning is widely practiced in tree fruit production to reduce labor cost, enhance fruit size, color, and maturity, and to ensure return bloom. Currently, two types of chemical thinning agents are used. The first is known as blossom thinner, which comprises caustic or desiccating compounds and is often applied during late bloom (around 80 percent full bloom). Examples are lime sulfur, sulfcarbamide, endothal, pelargonic acid, or ammonium thiosulfate. These compounds bum stigmas and stylesof open flowers, preventing fertilization and seed formation. The early-opened, fertilized flowers or unopened flower buds are not affected. A narrow time window is a disadvantage with these compounds. Blossom thinners do not kill unopened flowers and applying too early may kill the king bloom and leave the unopened lateral flowers to set smaller fruit. Timing to remove these lateral flowers by late application, on the other hand, may result in fruit russet or leaf injury. Another problem is inconsistency. The compound's efficacy depends on the percentage of fertilized flowers at application. If most of the opened flowers were pollinated and fertilized, application of a cartstic blossom thinner at 80 percent full bloom may produce inadequate thinning.However it may cause overthinning if few opened flowers were fertilized at 80 percent full bloom.