Effect of Repeated Fungicide Applications on Creeping Bentgrass Turf
- Zachary J. Reicher and
- Clark S. Throssell
Though fungicides are regularly applied to creeping bentgrass (Agrostis palustris Huds.) turf throughout a growing season, little is known about possible non-target effects of these applications on turfgrass growth and metabolism. The objective of this field study was to determine the effect of 3 yr of multiple applications of fungicides to ‘Penncross’ creeping bentgrass maintained under putting green conditions and on a native silt loam soil. Benomyl [methyl-1-(butylcarbamoyl)-2-benzimidazolecarbamate] at 3.05 kg ha−1, iprodione [3-(3,5-dichlorophenyl)-N-(1-methylethyl)-2,4-dioxo-1-imidazolidinecarboximide] at 3.05 kg ha−1, and propiconazole [1-(2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolan-2-ylmethyl)-1H-1,2,4-triazole] at 0.84 kg ha−1 were applied weekly or alternated with chlorothalonil (tetrachloroisophthalonitrile) at 6.36 kg ha−1. Sixteen applications were made in each of 3 yr. Propiconazole applied weekly or alternated with chlorothalonil increased clipping weights, turned bentgrass dark green, and decreased visual quality throughout the study. Chlorothalonil, propiconazole, and benomyl reduced water-soluble carbohydrate (WSC) concentrations of clippings during the study, this effect was most common in the heat of late summer. Benomyl applied weekly and chlorothalonil applied weekly or alternated with the other fungicides decreased earthworm activity. Propiconazole applied weekly or alternated with chlorothalonil increased damage from pink snow mold (Microdochium nivale Samuels and I. C. Hallett). Chlorothalonil applied weekly and alternated with the other fungicides increased rooting the last year of the study. Fungicides applied frequently did not have serious negative non-target effects on Penncross creeping bentgrass.
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