By Kathryn Carter, Fruit Specialist (Tender fruit and Grape), OMAFRA
In March the growng 2020 growing season appeared to be running about 1-2 weeks ahead of 2019 (which was a very late season). Consistently cool temperatures returned in April (Figure 1) slowing crop development considerably. Tree planting and pruning is ongoing in tender fruit orchards.
Niagara-on-the-Lake: Apricots in bloom (with some frost damage), peaches are at 25% bloom, early golden/shiro plums at bloom, nectarines at bloom
Beamsville: Apricots at bloom (with some frost damage), early golden plums at bloom, Shiro plums at 1st bloom, peaches at pink, nectarines at pink, pears close to first white
Norfolk: Tart cherries at green tip
Harrow: Apricot in bloom, pears early white, plums white to first bloom, peaches bud swell
With warm weather in the forecast for Friday, Saturday and Sunday, bloom will be advanced. Currently the forecasted temperatures are anticipated to be above freezing for the next week. However, where buds and bloom are present, watch the weather conditions and forecast for frost. There is considerable variation in the susceptibility to freezing between orchards, cultivars, crops and stages of development. As flowers begin to swell and expand into blossoms, they become less resistant to freeze injury. Buds that develop slowly tend to be more resistant. As a result, some buds are usually killed at higher temperatures, while others are resistant at much lower temperatures. The table of critical spring temperatures in this blog post shows the average temperatures required to kill 10 percent and 90 percent of buds. Keep in mind that weather conditions proceeding cold nights can affect bud hardiness. Prolonged cool weather tends to increase bud hardiness during the early stages of bud development.