NO ADVERSE EFFECT OF EARLY-SEASON FUNGICIDE AND ZINC SPRAYS ON LEAF-AREA, FRUIT-SET, AND NUT QUALITY OF PECAN

Propiconazole, a fungicide, suppressed leaf area of a wide variety of young pecan [Carya illinoinensis (Wangenh.) K. Koch] seedling genotype s but did not reduce leaf area of orchard trees, Leaf area declined li nearly as dosage increased from 0.16 to 1.25 mL . L(-1). Suppression o f leaf area by propiconazole was inversely proportional to leaf age, N o reduction of leaf area was detected in orchards where 'Cheyenne', 'D esirable', and 'Pawnee' were treated with three applications (14-day i ntervals) of fungicide (either propiconazole, fentin hydroxide, or fen buconazole) from budbreak to early May, Spring application of the thre e fungicides alone or in combination with zinc sulfate did not influen ce fruit set, Control of pecan scab [Cladosporium caryigenum (Ell, et Lang) Gottwald] was achieved with either fentin hydroxide or fenbucona zole for the full season, or with early season use of dodine, then pro piconazole, and then followed by fentin hydroxide for late-season dise ase control, Fungicide treatments had no effect on nut weight. These d ata indicate that fungicides applied to pecan during pollination at co mmercially recommended dosages and intervals, with or without zinc sul fate, do not adversely influence leaf area or fruit set of orchard tre es, Chemical names used: n-dodecylguanidine acetate (dodine); tripheny ltin hydroxide (fentin hydroxide); 2-(2,4-dichlorophenyl)-4-propyl-1,3 -dioxolan-2-yl] methyl]-1H-1,2,4-triazole (propiconazole); l]-alpha-ph enyl-1H-1,2,4-triazole-1-propanenitrile (fenbuconazole).