POSTERS: Chemical control
Management of black leaf spot of rose with fungicides
Fulya Baysal-Gurel - Tennessee State University. Mary Holden- Tennessee State University, Terri Simmons- Tennessee State University
Black spot (Diplocarpon rosae) is a destructive leaf disease of rose in the landscape and nursery production. The efficacy of fungicides against black spot of rose were assessed on rose 'Queen Elizabeth'and ‘Louis Philippe’. Six single-plant replications per treatment were arranged under 45% shade in a randomized complete block design.Treatments were Orkestra Intrinsic SC, Mural 45WG, Eagle 20EW and Broadform SC (4 and 8 fl oz/100 gal). Severity of black spot resulting from natural infections was determined during the experiment and expressed as the percentage of foliage area affected. All of the treatments significantly reduced black spot severity and area under the disease progress curve (AUDPC) throughout the experiment compared to the non-treated control for both cultivars. The treatments that most effectively reduced black spot severity were the high and low rates of Broadform, Eagle and Mural for ‘Queen Elizabeth’ and the treatments that most effectively reduced black spot severity were the high rate of Broadform, Eagle and Mural for ‘Louise Philippe’. There were no significant differences in disease progress between fungicide treatments for ‘Queen Elizabeth’. Treatment with the high and low rates of Broadform, Mural and Eagle were more effective in reducing AUDPC in ‘Louis Philippe’ than Orkestra Intrinsic. Non-treated control ‘Queen Elizabeth’ plants were not commercially acceptable due to the level of disease at the end of the trial.