Abstracts

Byrd, B. C., W. G. Wright, and L. E. Warren. 1975. Vegetation control with 3, 5, 6-trichloro-2-pyridyloxyacetic acid. Northeastern Weed Science Society Proceedings 29: 238.

3, 5, 6-Trichloro-2-pyridyloxyacetic acid, at rates from 0.5 to 9.0 lb. ae/a, has exhibited excellent herbicidal activity on a broad range of woody plants in performance trials on industrial sites in 15 states throughout the United States. These results suggest that this compound is more effective at lower rates than 2, 4, 5-T on a broader range of woody species. Established grasses were not permanently injured by the rates used in these tests. Forestry and rangeland trials are underway in one or more of eight states and trials of various kinds have been established in other countries around the world. Grass residue and watershed runoff programs are at various stages prior to completion and preliminary estimates of impact on non-target organisms are underway. Preliminary toxicological information indicates that the chemical has a moderate acute oral toxicity to mammals and should pose no problem from ingestion incidental to handling and spraying. The chemical also has a very low toxicity to fish and birds.

Dunbar, D. and G. Stephens. 1974. The two-lined chestnut borer, killer of oaks in Connecticut. Frontiers of Plant Science, fall, p. 4-5. Conn. Agr. Expt. Sta., New Haven.

Growing concern over the increasing numbers of dying oaks in the State in recent years has led us to investigate the role of a small beetle called the two-lined chestnut borer, Agrilus bilineatus (Weber). We have been studying the biology, life history, and control of this insect since the summer of 1972, when oak mortality became most noticeable. The adults feed upon oak foliage. Laboratory tests show that the leaves of scarlet and chestnut oaks are preferred over other species. However, the real damage results from larval feeding in the phloem and cambium. Oak mortality during the period 1969-73 ranged from 18 to 79 per cent. Mortality was least in areas where there was either no defoliation or a single defoliation in 1972 or 1973. The most mortality occurred where there was heavy defoliation in both 1970and 1971. Because adult beetles feed on oak leaves, control by conventional foliage spraying was attempted. Sprays of Imidan, Orthene, methoxychlor and Sevin applied to oak leaves and fed to caged beetles in the laboratory killed all beetles up to one week after application.

Kozel, P. C., E. K. Toth, and T. L. Mannell. 1975. Superior shade trees for the nursery/landscape industry. American Nurseryman, Jan. 1, p. 7, 8, 130-136.

The following selections of trees are those included in the shade tree evaluation planting at the Ohio Agricultural Research and Development Center, Wooster, Ohio, in cooperation with several Ohio utility companies, the Ohio Chapter of the International Shade Tree Conference, and the Ohio Nurserymen’s Association. Based on evaluations of members of an appointed shade tree evaluation committee, these trees have outstanding attributes and should be used more often in the nursery/landscape industry: hedge maple, Lavalle hawthorn, Washington hawthorn, Winter King hawthorn, and Snowdrift crabapple. Trees that are 30 to 45 feet in height at maturity are as follows: Autumn Flame red maple, Shademaster honeylocust, hop hornbeam, Chancellor little-leaved linden, Greenspire little-leaved linden, and little-leaved linden. The trees that are larger than 45 feet in height at maturity are as follows: Cleveland Norway maple, Emerald Queen Norway maple, Summershade Norway maple, October Glory red maple, Red Sunset red maple, Tilford red maple, Fraxinus, Autumn Purple white ash, Hesse European ash, Marshall’s Seedless green ash, Imperial honeylocust, Skyline honeylocust, Moraine sweetgum, and London plane tree.

• © 1975, International Society of Arboriculture. All rights reserved.