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As expected, the apple trees in Michigan are showing snowball bloom after freezes in 2012 gave them a year off from crop production. Michigan State University extension fruit educators are telling growers to take a “nibble thinning” approach to reduce crop load, or face a whopping crop this year, a small crop in 2014, and biennial bearing for years in the future.

“Nibble thinning is a strategy to chemically thin often and multiple times throughout the bloom and fruit set window,” said Phil Schwallier and Amy Irish-Brown in a document they e-mailed to growers on May 17. They also announced thinning meetings to be held this week.

They called the heavy bloom currently under way a “green snowball” because many varieties are well leafed out. Because the cold spring delayed the emergence from dormancy, there has been only one damaging freeze event, when temperatures on May 13 dropped to 24 ˚F at some locations.

“Growers will have to carefully assess frost damaged sites and adjust their thinning program accordingly,” they said. “Excellent sites and frost‐protected areas have almost no frost damage and need to be thinned aggressively. Bee activity, pollination, and even fertilization appear to be good. Temperatures for the next 7 to 10 days are forecast to be warm, ideal for excellent fruit set.”

To see Schwallier and Irish-Brown’s “apple thinning pointers for 2013,” including an excellent table describing rates and timing of thinner applications, go to msue.anr.msu.edu. Under the Agriculture tab, choose “Fruits & Nuts” and find it in the list of News topics.