Optimizing Manganese Fertilization for the Suppression of Take‐All Patch Disease on Creeping Bentgrass

Abstract

Take‐all patch, caused by Gaeumannomyces graminis (Sacc.) Arx. & D. Olivier var. avenae (E.M. Turner) Dennis, is a destructive disease of creeping bentgrass ( Agrostis stolonifera L.). Previous research has shown that Mn fertilization can reduce the severity of take‐all patch, but further research is needed to assess the impact of Mn rate and the time of its application on disease development and on the extended residual impact of Mn fertilization on disease suppression. The objective of the current study was to determine the best rate and time of Mn application for the suppression of foliar symptoms of take‐all patch on creeping bentgrass. On a golf course fairway naturally infested with G graminis var. avenae , Mn (as MnSO 4 ) treatments were applied as single applications in either October or April of 1998, 1999, or 2000 at 0, 2.25, 4.50, 6.75, or 9.00 kg ha −1 of Mn. The severity of take‐all patch was assessed each year during May and June when foliar symptoms were apparent. Throughout the study, compared with untreated turf, Mn effectively reduced disease severity when applied either in April or in October. Moreover, the 2.25 kg ha −1 Mn application rate was generally as effective in suppressing the disease as were higher application rates, except in the third year of the study when higher rates were more effective. Findings also suggest that across time previous applications of Mn fertilizer were less effective in suppressing take‐all patch than were the most recent applications of Mn.