Summer Pruning and Finalizing Crop Load

One of the great advantages of summer pruning that has really only recently been talked about very much is its apparent influence over the rate of transpiration of the apple tree canopy (Figure 1). Trees that are sufficiently summer pruned do not move as much moisture out of the orchard ecosystem than trees left with a full canopy. Coupled with other water conservation practices that include mowing, mulching, thinning, and efficient watering, the well-managed orchard has a higher probability of producing a larger fruit. All these practices of course add to the cost of production but create a positive cost/ benefit ratio.

Selective Hand thinning fits well with the practice of summer pruning and most growers looking for larger fruit of selected cultivars will remove a lot of inferior looking apples at the same time. By thinning the canopy through selective shoot removal, these poor looking smallish fruit come out of hiding. A small apple will always remain small in relationship to a large apple during the post fruit set period. Small apples do not make up size deficiency during the growing season.

Figure 1. Thinning down the apple canopy. Avoid removing an excessive amount of foliage. If you think you have overdone it with summer pruning, you probably have. The figure above shows a good summer pruning job with the removal of some fruit and up to 20-30% of the shoot growth.

This process of canopy management can be started before mid July in earlier areas of Ontario. It does take some practice to know just how far to space fruit apart on the limb to get those larger size classes. If we suggest a rough measurement from stem to stem of lets say 8 inches or around 20 cm. that would leave about 4 inches or 10 cm. between the edges of apples grown to a size of 3 inches or 113 count size at maturity.

There remains less and less logic in growing smaller fruit for North American fresh markets in general. One of the outstanding problems facing the average grower is that of handling a crop of smaller apples. Not only is it more costly to handle the crop in terms of picking, the value of the crop diminishes significantly with each reduction in size class.

A grower would have to grow several bushels of smaller fruit to equal the value of a couple of bushels of large well-finished apples. Two bushels of 113 size fruit could return as much as 5 or more bushels of lets say 150 size fruit. This is after the cost of picking with associated wastage from dropped fruit while picking. The cost of harvesting a large crop of small apples could be double the cost of harvesting an average crop of larger apples. Picking crews always move faster in a well-thinned block.