Although this is the time of the year we usually talk about rescue thinning treatments, this might not be necessary this year. The several days of cloudy and rainy weather last week (April 13-18) had resulted in natural fruit abscission in many varieties. Although the carbohydrate thinning model did not predict any natural abscission to occur, it showed a severe carbohydrate deficit in the last ten days. Today I was examining some apple blocks in our research farm, and I noticed a lot of apple fruitlets under the un-thinned trees. The size of abscised fruit ranged between 11.1 mm in Gala to 13.6 mm in York (see the figure below). Although this predicts over-thinning in blocks sprayed with chemical thinners early last week, it could be just fine with some varieties like Fuji where chemical thinning is not always effective. If natural fruit abscission or over-thinning is the case in your blocks, it might be wise to reduce the number/amount of return bloom applications as this might result in excessive blooming next season.