【沪江慢速VOA】2月27日: 美国白蜡树面临虫灾威胁(2)
Insect Threatens Ash Trees in US (2/2)
The United States Department of Agriculture is working to save the ash tree. So are agriculture departments and university extensions in a number of states.
In some places, farmers are using "detection trees." These have an area where bark has been cut away. The area circles the tree and is called a girdle. The girdling process weakens the trees. It makes them easier targets for borers, and shows if the insects are nearby.
Efforts to stop the spread of the emerald ash borer include cutting down affected trees. A tree farmer in Maryland, for example, recently faced the loss of hundreds of trees. There are worries that the ash tree might disappear unless the invasion is controlled. To prepare for such a possibility, a government laboratory is collecting seeds from ash trees.
David Burgdorf works in East Lansing, Michigan, for the Natural Resources Conservation Service; the service is part of the United States Department of Agriculture. He is asking people to send in ash seeds. The laboratory examines and x-rays the seeds to make sure there are no living borer embryos.
