Heavy rain and humidity increase crop disease Up North

Jul 9, 2019

Fire blight on an apple tree in Leelanau
Credit Peter Payette / Interlochen Public Radio

Fruit growers in northern Michigan are battling crop diseases this summer caused by heavy rain and humidity.

Nikki Rothwell coordinates research at the Northwest Michigan Horticultural Research Station in Leelanau County. She says she hasn’t seen outbreaks like these in the 15 years she has worked at the station.

Rothwell says rainfall at the research station was about twice what it normally is in June and the conditions are perfect for cherry leaf spot, a disease that is causing some tart cherry trees to lose all their leaves. At least one tree in her orchard has spots on the stems and fruit, something she almost never sees.

“If we have a hard winter, this could easily kill the tree,” she says.

Meanwhile apple trees are being hit with fire blight, a bacterial disease that Rothwell did not see last year and one that has not been a common problem up north. She says wet conditions like these may become more common in northern Michigan with climate change and make it hard to keep fruit trees healthy.

“It’s like growing things in a petri dish," Rothwell says. “You have that relative humidity that stays up, those pathogens are going to go crazy.”

Rothwell also expects the tart cherry crop this year will be harvested later than usual. That could mean growers will have an extra week or more to fight off diseases with sprays.