2013-02-07 / Life in Leelanau

Research may help control leaf spot

By Eric Carlson Of The Enterprise staff


CHERRY LEAF spot is a disease for which researchers have found a specific gene in cherry trees — a gene that could be used to control resistance to the disease. CHERRY LEAF spot is a disease for which researchers have found a specific gene in cherry trees — a gene that could be used to control resistance to the disease. Although last year’s weather obviously hurt Leelanau County’s cherry crop badly, a cherry tree disease that reached epidemic proportions last year was also a major factor in the dismal harvest.

Cherry leaf spot, with the scientific name Blumeriella jaapil, was a particularly difficult problem last year because it infects young tart cherry leaves during rainy weather. The weather last year left cherry trees particularly vulnerable to cherry leaf spot.

There are remedies to the disease, but they include spraying expensive chemicals on the trees — something farmers don’t like to do because it costs money. In addition, chemicals on their fruit is something consumers don’t want either.

“Wouldn’t it be great if we could not spray as much to control (cherry leaf spot) in trees?” Phil Korson, director of the national Cherry Marketing Institute asked rhetorically at last month’s Orchard and Vineyard Show in Grand Traverse County.

Michigan State University researcher Dr. Amy Iezzoni, in collaboration with many other researchers around the world, has been working on a genetic solution to cherry leaf spot. Researchers have discovered the very gene in cherry tree chromosomes that control resistance to cherry leaf spot. If they can breed cherry trees that activate the gene, they will likely solve the problem of cherry leaf spot.

“More chemicals are applied to control cherry leaf spot than any other tart cherry pest,” Iezzoni said. “Fortunately, the wild cherry species P. canescens is known to be resistant to cherry leaf spot,” she added.

Research is currently underway to test leaf spot resistance in commercial cherry trees cross-bred with the disease resistant wild cherries — and a solution may be on the way.

In the meantime, spraying fungicides on cherry trees may be the only solution to the problem. In 2012, researchers reported a “major cherry leaf spot epidemic” in northwest lower Michigan. A repeat of last year’s weather could result in another epidemic of cherry leaf spot in 2013, according to researchers.

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