Spraying sweet cherry trees with the plant growth regulator ethephon in autumn can delay spring flowering by more than a week in some cultivars, researchers at the University of Göttingen report, offering orchardists a possible tool against frost damage as warmer winters bring earlier bloom. The study, led by Wiebke Kämper, appeared in BMC Plant Biology.

The team applied ethephon, which releases the plant hormone ethylene, at 500 and 750 ppm in early and late autumn to Bellise and Kordia cherries and Elstar and Kanzi apples. In Kordia, 88 percent of untreated trees' buds were in bloom by 9 April, against 56 percent after an early high-concentration treatment and 63 percent after a late lower-concentration one.

But results were strongly cultivar-dependent, and the late high-concentration treatment on Kordia cut final fruit set from 16 percent to 6 percent. The researchers call the work a first demonstration of feasibility; growers would need cultivar-specific data on both bloom delay and fruit-set loss before adopting it.

Photo: Johan Neven / Wikimedia Commons (CC BY 2.0)

Source: Global Agriculture