Watch for Early Harvest of Cultivars Going Into Long Term Storage

One of the more outstanding trends I have observed in the last decade or two is the movement of average harvest dates away from the historical timings. Growers are having to make labour and equipment arrangements earlier on average than they have ever done in the past. 

Decisions around harvest date can be very complex especially with the introduction of new and various strains of cultivars. The range in maturity dates can be quite varied even for a variety like McIntosh. In Ontario, we now grow several different strains of Macs including Marshall®, Summerland, Imperial, Rogers, and Spur types, Marquis Mac, Pioneer Mac™ and now Miracle Mac. They each have their own peculiarities including the ways in which they ripen. This year we have had reports from growers who watch dates carefully saying that they are picking various tree fruit cultivars including some of the tender fruit varieties several days ahead of what we would call average and indeed several days ahead of their earliest ever dates found in their records. 

Earlier picking dates can be influenced by several things, not the least of which is the bloom date and date of pollination. When we mix in stress factors like heat, high UV or runaway mite populations acting directly on the foliage and fruit along with moisture deficits and various sprays that can influence the generation of ethylene in the tree canopy we have a recipe for earliness. 

Growers using aggressive treatments of calcium or perhaps a season long program of Surround Crop Protectant as we have found out can influence the best picking date for long term storage of fruit from a given block. It is only in recent years that we have had the ability to slow down the production of ethylene in the canopy and in the individual fruit with the use of ReTain. The problem here though is that ReTain is unlikely to over-ride the effects of various forms of tree and/or canopy stress. 

Growers are advised to watch the starch degradation in varieties like McIntosh very carefully and to plan accordingly.