W. B. Dong, Department of Plant Pathology, University of Georgia, Griffin, GA 30223;
S. N. Jeffers, School of Agricultural, Forest, and Environmental Sciences, Clemson University, Clemson, SC 29634; and
J. W. Buck, Department of Plant Pathology, University of Georgia, Griffin, GA 30223
The objectives of this study were to assess the efficacy of various fungicides applied as root dips, soil drenches, or foliar sprays to daylily plants grown in containers and planted in the field to manage rust caused by Puccinia hemerocallidis. Soil drenches and foliar sprays were evaluated in field experiments in Griffin, GA in 2010 and 2011. Dipping bare-root daylily plants for 5 min in azoxystrobin, tebuconazole, or thiophanate-methyl significantly reduced lesion development compared with nontreated control plants. Drenches with azoxystrobin, fluoxastrobin, or tebuconazole, each at three rates (0.06, 0.12, and 0.24 g of active ingredient [a.i.]/container), significantly reduced development of rust lesions on container-grown daylily plants for up to 9 weeks after treatment and 6 weeks after inoculation. One early-season drench of azoxystrobin at 0.12 g a.i‥/plant provided season-long reduction in disease incidence and disease progress that was comparable with foliar sprays with azoxystrobin or chlorothalonil applied at 14-day intervals. Dip or drench applications of fungicides would allow growers to diversify rust management options and could reduce the number of foliar fungicide applications.