Maple decline

Sugar maple along a city boulevard showing signs of decline due to environmental stresses.

Multiple-year stress events continue to take their toll on the southern region?s sugar maples. The city of Rochester estimates 250 maples were removed from boulevards in 2002. They estimate 200 more will be removed in 2003.

A string of warm winters, unseasonably warm days in spring and hot, dry summers have stressed urban sugar maples. It was deja vu again in 2002. Despite the early season rainfall, the weather turned hot and dry by mid-July. Acute leaf scorch and early fall coloration were common. By August, widespread dieback and mortality was observed.

What is maple decline?

Long time US Forest Service researcher, Dave Houston defined maple decline in 1967 as A A progressive disease condition that begins when the trees are altered initially by stress and continues as they become invaded by organisms of secondary action. Maple decline is primarily the failure of sugar maples to be grown successfully as shade trees in many locations,? according to Terry A. Tatter, author of Diseases of Shade Trees.

Why do problems arise in the urban environment?

Sugar maples are found in northern hardwood forests, where the soils are deep, fertile and well-drained and where there is abundant organic matter. Sugar maples cannot take the climatic stresses associated with urban sites and cultural issues involving poor planting practices compound the problem.

Sugar maple along a city boulevard showing signs of decline due to environmental stresses - this one showing stem girdling roots.

Field examinations and excavations of symptomatic maples in urban areas this season consistently found that trees were planted too deeply and trees had stem girdling roots. An example is shown in the photo above.

Note the decline in the foreground maple and the stem girdling roots seen with just a brief soil excavation around the root collar. Also note the older non-symptomatic sugar maple in the background planted many years before. In rural areas it has been common to find Armillaria root disease associated with symptomatic trees. In these recent surveys, evidence of Verticillium wilt was not seen.