September 30, 2012

Climate change may boost state's cranberry take

By North Cairn
Staff Writer

Maine's cranberry harvest is up this year, and one Cooperative Extension specialist believes that warmer weather brought on by climate change might be one reason.

click image to enlarge

John Ewing/Staff Photographer

Charlie Armstrong, a cranberry specialist with the Cooperative Extension at the University of Maine in Orono, said the warming weather since the mid-19th century -- an average 1.5 to 2 degrees Fahrenheit globally -- may be a harbinger of changes to come for agriculture across the state.

If the average temperature were to rise even a couple more degrees, he said, the difference could be significant, opening up parts of Maine to crops such as peaches, ordinarily grown as far south as Georgia, where the peach is the signature fruit.

Now, Maine peaches are so rare they almost qualify as exotics. They are grown only in small numbers in semi-rural areas like Albion and Bowdoin.

"I never thought it would be possible to grow peaches in Maine," said Armstrong. One grower has even decided to plant kiwis.

In contrast to peaches and kiwis, Maine cranberries, which represent a mere 1 percent of the nation's total crop, seem like a large-scale agricultural staple.

Armstrong said the 2012 cranberry harvest, which begins this week in many bogs, is expected to yield 25,000 barrels, or 2.5 million pounds, from a total of only 210 acres of beds and bogs statewide. About half are in Washington County.

This year's yield is still slightly less than the 2010 "best ever" year when more than 29,000 barrels were harvested, Armstrong said. But it exceeds last year's crop of about 23,700 barrels -- and final results are not yet in.

For cranberries, like apples earlier this fall, the misfortunes of other parts of the nation have meant good news for Maine farmers.

Despite an increase in troubles this year with such pests as worms and moths, the cranberry crops "are looking super, overall," Armstrong said. Cranberry fruitworm populations were very high this year -- as much as three times more than normal. But even the most seriously affected growers lost only 5 percent to 10 percent of their crop.

Armstrong blamed the mild winter for high fruitworm and moth populations. More balmy temperatures "favor the over-wintering stage, halfway between the larva and the moth," of the cranberry fruitworm, a pest that can devastate the crop.

A fungus known as root rot also caused an incremental loss in yield this year -- about 1 percent statewide, which is typical, he said.

In many respects, climate change could "prove beneficial," said Armstrong. A further rise in temperatures could have a negative impact on growers in states such as Massachusetts and New Jersey, traditionally big producers. And it would likely mean conditions in Maine would be more favorable for the berries, which can tolerate the warmer temperature but prefer cool nights.

On the flip side, such weather changes could also be a boon to insects, Armstrong said. "For some growers, it might be more of a headache, because there might be more pests."

It's a problem that cranberry growers here struggled with during the growing season in the form of cranberry fruitworms and fruit rot, along with the threat of a new species of fruit fly, the spotted-wing dropsophila.

But "narrow chemistries" in newer pesticides, which have replaced many of the more deadly organophosphates, helped keep yield up by eliminating pests that ordinarily take as much as 40 percent of an untreated crop, Armstrong said.

(Continued on page 2)

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