Mosquitoes thriving, Md. crops suffering amid rainy weather

Jun 18, 2009      The Baltimore Sun

Frank D. Roylance

Jun. 18, 2009 (McClatchy-Tribune Regional News delivered by Newstex) -- As Marylanders slosh through their third straight month of rainy weather, the state's mosquito control chief says we have more to worry about than gloomy skies and spoiled picnics.

Mosquito populations have exploded, and they're looking for blood.

"This could very well be the worst year we have had in a couple of decades if this rainfall pattern keeps up," said Mike Cantwell, chief of the Maryland Department of Agriculture's mosquito control division.

His crews measure mosquito populations by counting how many land on their arms in a minute. On the lower Eastern Shore, 12 per minute is enough to call for aerial spraying.

"We've had counts... of over 90 a minute at some sites in southern Dorchester County. The average is about 54 landings per minute," Cantwell said. "Somerset and Wicomico counties have landing rates on average of 30 to 40 a minute."

Mosquito counts are also high and rising across Central Maryland. Counts of three to five landings per minute are common in Baltimore County, with five to 10 a minute along the Back, Middle and Gunpowder rivers.

Those are mostly salt marsh and culex species, which breed early in the season.

In urban areas, Asian tiger mosquitoes -- persistent daytime biters -- are busy breeding in clogged gutters and backyard containers. "At some point, I would expect we will ultimately be above normal levels for tigers this year, too," Cantwell said.

So far, no mosquitoes have tested positive for diseases such as West Nile fever or encephalitis. But the first positive "pools" generally don't turn up until July, he said.

Last year, four batches from the Patuxent Wildlife Research Center tested positive for the deadly eastern equine encephalitis.

About 2,100 Maryland neighborhoods are participating in the state's voluntary mosquito aerial and ground spraying programs, and the money is going fast.

"At this pace, we will expend our budget probably in midseason," Cantwell said. "We'll have to slow down or we'll have to request [more] funding." But given the state of the economy, he's not hopeful of getting an emergency appropriation.

Meteorologists blame a pattern of cold fronts that have stalled across the region since April. The fronts have funneled showers and thunderstorms across the mid-Atlantic states, and there are few signs that the pattern is changing.

"It's just day by day, week by week," said Jay Searles, a meteorologist with Penn State Weather Communications. "There are some indications [the front] is starting to shift farther north, especially in the west."

But for now, the Maryland forecast calls for more showers and thunderstorms through the weekend.

The wet weather began early in April, ending a very dry stretch through the fall and winter that by late March had reached drought proportions.

Since April 1, Baltimore-Washington International Thurgood Marshall Airport has reported more than 17 inches of rain, nearly double the long-term average and a surplus of 8.6 inches.

Eleven weeks of abundant rain have restored stream flows across the state, raised water levels in the region's wells and filled the Baltimore reservoir system to nearly 99 percent of capacity.

Drinking water quality remains fine despite the added runoff. But the Maryland Department of the Environment reminded residents with wells to have their water tested once a year.

In the 77 days since April 1, the National Weather Service says, there have been only 10 days at BWI it could rate as "clear."

Across the state, the rainy weather has delayed winter grain crop harvests, slowed spring planting and cut yields, even as it washes away some crop pests and encourages others.

"The wheat crop probably concerns me the most. ... Every day it rains reduces the quality and prices," said Maryland Agriculture Secretary Earl "Buddy" Hance. "There's never a dull moment in agriculture."

Jason Scott of Hurlock on the Eastern Shore farms about 1,700 acres of corn, soybeans, wheat, barley and, this year, peas.

"We were late getting started planting corn, which in turn makes us late with our soybeans," he said. "It was just too wet to get out there."

The rain delayed his winter barley harvest and diminished the yield by 20 percent. "I also had to replant about, probably, 10 percent of my corn," he said.

Some of his corn is stunted, he said. "And instead of being a nice, bright green, it's yellow."

Rainy weather can mean hard times for crop pests, such as thrips and cabbage worms, and for beneficial insects, said entomologist Galen Dively, professor emeritus at the University of Maryland.

While the rain has kept clover and other flowering plants in bloom longer this spring, honeybees have had a hard time getting out to forage among the blossoms.

"I just came from the farm," Dively said, "and they're just snuggled in the hive."

Newstex ID: 35856743

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