Abstract
To assess the effectiveness of Remedy Ultra® (triclopyr), two studies were conducted during 2008–10 to control citrus stump sprouting after HLB-infected tree removal. The first study (2008–09, Arcadia) examined various application rates of Remedy (25%, 50%, and 75% mixed with diesel fuel) whereas, the second study (2009–10, Arcadia and Lake Placid) looked at the impact of delaying application of Remedy on the control of sprout formation. During the first study, 12 of the 15 (80%) untreated stumps sprouted. Sprouts were noted over the study period with 0, 5, 3, 1 and 3 of the 15 stumps sprouting initially at approximately 30, 60, 90, 120, and 150 d after tree removal, respectively. All treated stumps, regardless of the treatment rate, remained sprout free during the study period. For the second study, treatments of Remedy were applied at 25% or 50% solution mixed with diesel fuel at time of clipping, 24, 48, and 72 h later and compared to untreated controls. At Lake Placid, 7 (100%) untreated stumps sprouting by 150 d after tree removal. Four stumps within the 56 treated stumps had root sprouts but not from the treated stump. Remedy Ultra was slightly less effective in controlling sprouts when applied at the 25% Remedy/75% diesel than at the 50% rate. Delaying application and using the lower herbicide concentration rate also had a slight negative impact on sprout control. At Arcadia, 86% of the untreated stumps sprouted within 90 d of clipping with only one treated stump sprouting. These studies support the use of Remedy Ultra as an effective tool in controlling sprout formation and the importance of timely application to stumps, within 72 h of clipping, for sprout control.
