Summer Weather Leaves It's Signature on Apple at Harvest

Characteristic growing conditions for any area of Ontario can change dramatically from year to year. The summer of 2005 will be remembered for its volume of heat and sunshine from spring right through to first pick of early cultivars. For most growers, irrigation was critical in achieving fruit size and volume this year. Lack of rainfall had a definite effect on fruit size in some blocks. This is especially true where apple fruitlet thinning results were not satisfactory.

Trees can handle larger volumes of fruit through to maturity if they are not in a stressed situation. Irrigation in combination with particle films have played a large role in alleviating tree stress this year.

2005 has been an excellent year in which to grow ‘Golden Delicious’ in Ontario. ‘Golden Delicious’ is notorious for its inability to resist russeting and poor skin finish under average Ontario growing conditions, which include a good volume of cool wet weather in the spring and early summer. We did not really get those conditions this year.

We had lots of heat, sunshine and warm air beginning the first few days of spring. ‘Golden Delicious’ cannot be grown everywhere in the Province, however some surprisingly good looking Goldens were produced this year in areas considered to be marginal. Growers producing ‘Golden Delicious’ types of apples, including the various strains and look alikes, have had an excellent year in which to test finish of some of these newer yellow skinned apples. Many of these ‘Golden Delicious’ types mature weeks ahead of the well known ‘Golden Delicious’.

Cultivars that express a high susceptibility to mildew did not fair so well this year. Mildew usually expresses itself as a coarse russeting on the skin surface, which can show up almost overnight on the fruit in the late summer and in the preharvest period. Varieties like ‘Fuji’ and ‘Honeycrisp’ are very susceptible to mildew induced skin russeting.

Due to the warm, sunny summer in 2005 it should be a low risk year for low temperature disorders, such as core browning and flesh browning.

However, there is a high risk for senescent breakdown, external CO₂ injury, and superficial scald for the same reason.

Research has also shown that cooler temperatures in the preharvest period result in less watercore and a reduced susceptibility to superficial scald on apple.