Obliquebanded leafroller (OBLR) larvae feed on apple blossoms and developing fruit. Many OBLR-damaged apples drop from the trees prematurely, and those that stay on the trees develop deep, corky scars and indentations. In 1996, Cornell University scientists studied the potential of Trichogramma platneri for control of this pest in New York.
T. platneri was released in large numbers in both a commercial orchard and an unsprayed, research orchard, and the rates of parasitism of OBLR egg masses by the wasps were recorded for several weeks.
The wasp's effect on OBLR damage varied. Damage to McIntosh and Cortland apples at the research orchard was 50-70% lower than in plots where no wasps were released. But damage in the Delicious apples in the same orchard was not reduced at all. In the commercial orchard, damage was reduced by 10% in Jerseymacs, but the wasps seemed to have no effect in the Cortland plots.
It appears that wasps alone are not likely to provide adequate management in orchards heavily infested by OBLR. But using Trichogramma in combination with other control methods could enable growers to reduce pesticide applications for leafrollers by 30-50%. Eliminating at least some of the standard insecticide sprays may also enhance biological control of mites (see MBCN Vol. I, Nos. 1, 2, 3, 4).
New York State Integrated Pest Management Program Annual Report, 1997.
Return to Commodity Menu Vol. IV No. 10
Return to Contents Menu Vol. IV No. 10
Go To Index