ABSTRACTS

Shigo, A.L. and Alex Shigo. 1974. Detection of discoloration and decay in living trees and utility poles. USDA Forest Service Research Paper NE-294. Upper Darby, Pa. 11 p.

Discoloration and decay are major causes of damage to living trees, utility poles, and wood products throughout the world. They are caused by bacteria and fungi that digest wood inside of trees and poles, hidden from view. A method is described for detecting discoloration and decay in living trees and creosoted utility poles. The method and devices have come from research involving many people over a seven-year-period. A probe was inserted into a 3/32-inch diameter hole made by drill bits 8 inches and 12 inches long mounted in a portable, light-weight, battery-operated drill. The probe was attacehd by a flexible cable to a portable, light-weight, battery-operated meter, a “Shigometer”, that delivered a pulsed electric current and measured resistance to it. As the probe was inserted into the hole, the meter measured in ohms the resistance of the wood in contact with the probe tip. As the probe was pushed inward, if the tip contacted only sound tissues, slight changes in resistance were measured. When the probe tip passed from sound wood to discolored or decayed wood there is an abrupt decrease in resistance. The magnitude of the decrease in resistance indicated the degree of discoloration or decay. The depth of the probe when the needle on the meter began to decrease indicated the position of the discolored or decayed wood.

Loomis, R.C. and W.H. Padgett. 1975. Air pollution and trees in the East. USDA Forest Service State and Private Forestry, NE and SE Areas. 28 p.

The benefits from trees are not limited to the rural countryside. Their importance in urban areas is recognized today more than ever. Among other benefits, they provide esthetic settings, cooling shade, and protection from wind, dust, and noise. Air pollution levels are high enough in some areas to cause plant injury. This is true not only in and around some of the larger cities, but also in rural areas where large pollution sources are present. The air pollutants discussed in this publication are sulfur dioxide, oxidants, fluorides, ethylene, oxides of nitrogen, ammonia, chlorine and hydrogen chloride, and particulates.