Agrimycin 17 21.2W (streptomycin sulfate), Aliette WDG (fosetyl-Al), Kocide 101 77W (copper hydroxide), Phyton 27 (copper sulfate pentahydrate), and the experimental fungicide fluazinam 500F were evaluated for the control of fire blight (Erwinia amylovora) on field-grown crabapple. A block of bare-root flowering crabapple (Malus sp.) ‘Snowdrift’ was established in 1995, and the study was conducted in 1996, 1997, and 1998 at the Brewton Experiment Field in Brewton, AL (USDA Plant Hardiness Zone 8a). In all three years, streptomycin sulfate was the only product that significantly reduced the severity of fire blight. Typically, damage on the Agrimycin 17-treated trees was unobtrusive and restricted to the death of a few scattered bloom clusters (strikes). In two of three years, fire blight damage levels on the Kocide 101-treated trees were intermediate between those sprayed with streptomycin sulfate and the unsprayed control. Although intermediate disease control was also obtained in 1996 with Phyton 27, this fungicide/bactericide failed to significantly reduce disease severity in 1997 and 1998 as compared to the unsprayed control. In all three years, no significant reduction in the severity of fire blight was obtained with Aliette WDG or fluazinam 500F.
2Professor, Department of Entomology and Plant Pathology; e-mail: <email@example.com.>
3Superintendent, Brewton Experiment Field.