Early Curative Dollar Spot Control in Creeping Bentgrass as Influenced by Fungicide Spray Volume and Application Timing

摘要

The importance of spray volume and application timing of a fungicide targeting dollar spot (Sclerotinia homoeocarpa F. T. Bennett) has been investigated, but with conflicting results. The objectives of this field study were to assess the influence oftwo spray volumes (468 and 935 liters water/ha) and two application timings (AM to a canopy wet with dew versus PM to a dry canopy) for fungicides targeting dollar spot curatively. Chlorothalonil (8.5 kg a.i./ha), propiconazole (0.5 kg a.i./ha), and a tank-mix of chlorothalonil + propiconazole were compared on fairway height stands of renshaw?(2007 and 2008),ackspin?(2008), and rovidence(2009) creeping bentgrass (Agrostis stolonifera L.). There were no spray volume differences in 2007 or 2009. In 2008 in Crenshaw, there was less dollar spot in chlorothalonil-treated plots using the low versus high spray volume, but the opposite occurred in Backspin. Less dollar spot developed in propiconazole-treated plots subjected to the low versus high spray volumein Crenshaw in 2008. Higher levels of dollar spot developed in plots treated with propiconazole in the PM compared to the AM in 2009. The tank-mix of chlorothalonil + propiconazole was unaffected by spray volume or application timing at all sites. The preponderance of data indicated that the curatively applied fungicides generally provided similar levels of dollar spot control at the two spray volumes and application timings evaluated.