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Hollow tine core cultivation is practiced for the management of creeping bentgrass [Agrostis stolonifera L. var. palustris (Huds.) Farw.; syn. A. palustris Huds.] golf course greens and fairways to increase water infiltration, increase turf root and shoot growth, and control thatch. Benomyl [methyl 1‐butylcarbamoyl)‐2‐benzimidazole carbamate] is commonly used on turf as a soil drench for the control of disease such as dollar spot (caused by Sclerotinia homoeocarpa F.T. Bennett). Our objective was to determine the effect of core cultivation on the movement of a systemic pesticide in thatch and soil and the uptake by turfgrass using benomyl as a model. Core cultivation was conducted 1, 7, and 14 d before benomyl application in a field trial during 1992 and 1993 to study the effect of coring and time of coring on the movement and uptake of benomyl and control of dollar spot disease. Fungicide levels in turfgrass clippings, thatch and soil were determined by bioassay. Core cultivation 1 d before benomyl treatment provided the longest lasting uptake of benomyl and control of dollar spot disease compared with 7 and 14 d before benomyl treatment. Clipping, thatch, and soil samples from areas close to the coring holes had significantly higher (P = 0.05) levels of fungicide residues than those farther from the coring holes. This study suggests that core cultivation shortly before benomyl application can increase movement of benomyl into thatch and soil, thereby increasing uptake of benomyl by turfgrass and improving disease control.

Bioassays using pellets of agar, thatch-agar and turfgrass-agar were developed using benzimidazole-sensitive Penicillium expansum Link, to detect the fungicide methyl benzimidazol-2-ylcarbamate (MBC) which is the major fungitoxic degradation product of benomyl [methyl 1-(butylcarbamoy1)benzimidazol-2-ylcarbamate] in thatch and turfgrass clippings. These bioassays were used to estimate the amount of fungicide that was biologically available and hence, by subtraction from that applied, the amount that remained bound and biologically unavailable. The limit of quantitation was 0.5 mg kg-'. From 19.9% to 93.2% of the applied fungicide was bound by thatch and 46.2% to 56.9% was bound to turfgrass clippings depending on the concentrations used. In-vitro degradation studies showed that MBC had a half life of approximately 2.5 weeks at 23°C in non-sterilized thatch.

Bioassays using pellets of agar, thatch‐agar and turfgrass‐agar were developed using benzimidazole‐sensitive Penicillium expansum Link, to detect the fungicide methyl benzimidazol‐2‐ylcarbamate (MBC) which is the major fungitoxic degradation product of benomyl [methyl 1‐(butylcarbamoyl)benzimidazol‐2‐ylcarbamate] in thatch and turfgrass clippings. These bioassays were used to estimate the amount of fungicide that was biologically available and hence, by subtraction from that applied, the amount that remained bound and biologically unavailable. The limit of quantitation was 0·5 mg kg−1. From 19·9% to 93·2% of the applied fungicide was bound by thatch and 46·2% to 56·9% was bound to turfgrass clippings depending on the concentrations used. In‐vitro degradation studies showed that MBC had a half life of approximately 2·5 weeks at 23°C in non‐sterilized thatch.

No abstract