Tuesday, March 25, 2008

Week of March 23

Updated March 27

Climate Change May Be Fueling A New Generation Of More Aggressive Weeds

Research shows that global warming may be fueling a new generation of more aggressive weeds that compete with crops and are more difficult and costly to control. Already backyards across America are seeing bigger poison ivy plants with a more virulent form of the oil that causes an itchy rash. And studies show that a doubling of carbon dioxide can lead to a quadrupling of the pollen produced by ragweed -- bad news for hay fever sufferers.

One of the major characteristics of a warming planet is an increase in the amount of carbon dioxide in the atmosphere. Rising carbon dioxide has been shown to help vegetable and grain crops grow more quickly, become more drought-resistant and produce potentially higher yields. Unfortunately, though, the impact of rising carbon dioxide seems to be far more pronounced in the weeds that compete with crops than in the crops themselves.

"Weeds are survivors," said Lee Van Wychen, director of science policy for the Weed Science Society of America. "They can fill various niches and thrive under a wide range of conditions. While we have about 45 major crops in the U.S., there are more than 400 species of different weeds associated with those crops. There is always another weed species ready to become a major competitor with a crop if growing conditions change, such as an increase in carbon dioxide levels."

The impact of rising carbon dioxide levels on weeds can be striking. In a study conducted by Dr. Lewis Ziska of the U.S. Department of Agriculture's Agricultural Research Service, weeds grown under urban conditions of warmer temperatures and more carbon dioxide - conditions anticipated for the rest of the world in 50 years - grew to four times the height of those in a country plot 40 miles outside the city, where carbon dioxide and temperature reflected background conditions.

Ziska's research shows that common ragweed plants exposed to higher levels of carbon dioxide dramatically increased the amount of pollen they produced. A doubling in carbon dioxide led to a quadrupling of pollen. Some people are allergic to ragweed pollen, resulting in the "hay fever" response, including sneezing and watery eyes. Additional work by Ziska also suggests that even recent increases in carbon dioxide during the last 50 years may have led to bigger poison ivy plants with a more virulent form of the oil that causes people to break out in a rash. Full Article


Herbicide treatment postponed at Glenmere Lake, Florida

By Matt King, Recordonline.com

A controversial plan to treat Glenmere Lake with herbicide is off — at least for a year, and maybe for good. You can either blame or thank the northern cricket frog, the tiny amphibian that seems to have more power than Florida village officials.

Although the state Department of Conservation just awarded the village a $48,000 grant to treat the village’s drinking water supply with herbicide to kill an invasive plant species, it’s stopping the project unless the village can prove the herbicide won’t harm the frog.

Village officials will consider other options, much to the delight of [some] environmental advocates who maintain removing the plant manually or by stocking the lake with watermilfoil-chomping critters would be cheaper and more effective. Full Article


Insect-killing worms may help New York

By William Kates, Associated Press Writer

Each spring, tens of millions of alfalfa snout beetles rise from the soil to continue their slow, methodical march across upstate New York, laying waste to fields of alfalfa in a single growing season.

Now, after 20 years of research, Cornell University scientists have discovered a pair of microscopic, insect-killing worms that prey on the beetle, an invasive species that has infested 500,000 acres in nine counties - nearly 14 percent of the state's cropland - since it was first identified in 1933. Scientists hope the nematodes will be part of a two-pronged approach to thwart the wingless weevil. Cornell plant breeders also are working to develop a resistant variety of alfalfa.

The alfalfa snout beetle was first reported in North America in 1896 in Oswego, likely deposited from ship ballast. Farmers first reported it as a pest in 1933, about a decade after alfalfa was planted as a forage crop in New York. The spread of the alfalfa snout beetle has been limited to northern New York and parts of the Canadian province of Ontario. Full Article


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