A hand-held mechanical blossom thinning device for fruit trees.

摘要

Blossom or green fruit thinning is a common practice for producing larger and higher quality fruit in tree fruit production. Mechanical blossom thinning could decrease production costs when compared to hand thinning of either blossom or green fruit. In stone fruit, a few chemical thinning agents are available or reliable. In apple, chemical thinning agents are under regulatory scrutiny, and efficacy is highly dependent on weather. This study aimed to develop a hand-held mechanical thinning device suitable for thinning blossoms on fruit trees pruned to different architectures. Research prototypes of different configurations have been developed, fabricated, and tested in blossom thinning operations in commercial orchards. Results obtained from field tests verified that a hand-held mechanical blossom thinner could effectively remove blossoms from apple, stone fruits, and sweet cherry. Among all evaluated parameters, spindle speed appeared to have the greatest direct effect on the capacity to remove blooms. Field test results indicated that the test device could remove 61.1%, 30.8%, and 18.0% flowers on a single branch with a swipe around 0.5 m.s-1 under high (2500-3000 rpm), medium (1500-1800 rpm), and low (500-800 rpm) speed settings, respectively. In trees trained to central leader architecture, 85 s was required to remove 50% of blossoms using the hand-held mechanical thinner and at least 180 s when the task was accomplished by hand. Field tests also revealed that a better ergonomic design of the device could further improve operational efficiency.