Inhibition of Photosynthesis in Pecan Leaves by Fungicides. B. W. Wood, Horticulturist, U.S. Department of Agriculture, Agricultural Research Service, Southeastern Fruit and Tree Nut Research Laboratory, P.O. Box 87, Byron, GA 31008. J. A. Payne, Entomologist, and T. R. Gottwald, Plant Pathologist, U.S. Department of Agriculture, Agricultural Research Service, Southeastern Fruit and Tree Nut Research Laboratory, P.O. Box 87, Byron, GA 31008. Plant Dis. 69:997-998. Accepted for publication 20 May 1985. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1985. DOI: 10.1094/PD-69-997.

Four fungicides used for pest control on pecan (Carya illinoensis) reduced net photosynthesis (PN) of mature leaves in an orchard by 20% within 1 day of treatment. Foliage sprayed with propiconazole, benomyl, or triphenyltin hydroxide recovered within 5 days of treatment, but foliage treated with dodine did not recover until 17–31 days after treatment. Leaves showed no visible damage as a result of treatment. When PN was measured 13 days after each of four applications of triphenyltin hydroxide or propiconazole at 14-day intervals, triphenyltin hydroxide always suppressed PN about 20% and propiconazole had no significant effect.

Keyword(s): pest management, energy reserves.