Dollar spot, caused by Schlortinea homeocarpa F.T. Bennett, is a common turfgrass disease on golf courses, particularly, on creeping bentgrass (Agrostis stolonifera L.) putting greens. Fungicide resistance to Thiophanate-methy, iprodione, and /or propiconazole in this pathogen was observed in nine of ten golf courses sampled in Tennessee and Northern Mississippi. As a result, two studies were conducted to determine the effect of volatiles generated from Indian mustard (Brassica juncea L. Czerniak) seed meal, as a bio-control for dollar spot. In vitro results indicated that the isothiocyanates emitted by the mustard seed meal residues (MR) significantly inhibited mycelial growth by 100% at 0.05, 0.1, 1.0, 2.0, 5.0, and10.0 g MR L-1, respectively. Mycelial growth was only inhibited for 48 hours at 0.01 g MR L-1, and for 24 hours at 0.001 g MR L-1. The phytotoxicity effect of the isothiocyanates emitted by the MR was evaluated in field studies on two Crenshaw creeping bentgrass putting greens. MR were applied as a dry granule to the surface of the putting green and irrigated. Unacceptable injury occurred between the 0.5 and 1.0 g MR L-1 rates. These studies demonstrate the potentials for mustard residues as a bio-control for dollar spot on creeping bentgrass putting greens. Field studies to determine application frequencies/intervals and control of dollar spot mycelial growth in putting green conditions is warranted.
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