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Feature_article__Green_Trees

Feature Article July 10

Feature Article July 10,2003

LAND O' LAKES NewsWeb Home

Green Trees are BrownThis summer many conifers that should be green are brown to various degrees, including completely brown. There are several causes.

White pine close to highways, especially on the downwind side, are brown because of the salt spray shot onto them by snowplows. Modern snowplows can shoot a powerful spiralling twister of snow and salt powered by the movement of the truck. Under some conditions, fast-moving plows can throw salty slush many metres to the side and up in the air. White pines are particularly sensitive to such salty slush. It dries out their needles. Other conifer species also are sensitive, so people put up burlap and plywood to protect hedges.

Most conifers also have suffered from severe droughts in the last two summers. Some medium-sized balsams and white pines died as a result, especially on upland shallow soils.

Some green needles may be brown because of a very warm period last March. It thawed their tissue, which then froze in the following cold temperatures.

White cedars can have any of these problems, plus one more called cedar leaf miners. Four species of these little insects burrow inside the tips of cedar leaves. Periodically they cause problems for people who sell cedar branches for cedar oil. This year the cedar leaf miners seem to have caused a lot more brown cedar foliage. Wayne Ingraham, forest disease specialist with the Ministry of Natural Resources in Kemptville, visited the Highway 7 corridor to inspect the damage. He suspects that drought stress may have made some cedars more susceptible to the miners. Fortunately cedars can lose up to 80 percent of their foliage and still survive. However, even in wet areas some cedars appear dead.

With the participation of the Government of Canada