High orchard performance depends on good thinning programmes

2015-11-08 | Written by John Wilton, AgFirst | Australian Fruitgrower article

John Wilton argues that thinning is one of the most important orchard husbandry tasks for maximising both yield and fruit quality. OrchardNet™ data showed productivity gains in modern intensive systems, with top-performing blocks of major varieties reaching very high yields, but sustaining those yields depends on bringing crop load to optimum levels early.

The article stresses that chemical thinning should not be expected to remove the need for hand thinning. For strongly biennial varieties, optimum fruit numbers should be reached within roughly four to six weeks after full bloom. Fuji, Braeburn, Golden Delicious and Scifresh are highlighted as varieties where delayed crop-load reduction increases the risk of poor return bloom.

Fruit and cluster counts provide the basis for a block-specific thinning strategy. Wilton recommends using branch cross-sectional area as a guide to fruit number, generally around three to five fruit per square centimetre BCA depending on variety, and monitoring hand thinners against those targets.

Crop load also has a major effect on colour and harvest value. Early thinning to well-spaced fruit, followed where appropriate by a later quality pass, can improve size and colour while reducing the cost of harvesting and handling fruit that will not meet Class 1 specifications.