Disease resistance of shrub roses in a simulated landscape planting, 2008.

摘要

On 14 Feb 08, bare-root roses were transplanted into raised beds in a Benndale (A) sandy loam soil on 8 ft centers with 13 ft between rows. Prior to planting 600 lb/A of 5-10-15 analysis fertilizer was applied to the beds and incorporated. After a drip irrigation system was installed on 12 Mar, the beds were mulched on 1 Apr with fresh aged pine bark. An application of 0.4 oz/plant of ammonium nitrate on 7 Apr was followed by 29May and 16 Jul applications of 1.1 oz/plant of a 16-4-8 analysis fertilizer. Pre-emergent weed control was obtained with 28 Feb and 9 Sep applications of 2 qt/A of Surflan + 1.0 lb/A of Gallery. Sedgehammer at 1.3 oz/A was applied to the beds on 17 Jun to control yellow nutsedge. The experimental design was a randomized complete block with five three-plant replicates. The study consisted of a split plot with five replications of roseselections as the main plot and fungicide treatment as the split-plot. Daconil Weather Stik 6F at 2 qt/A was applied at two or four wk intervals to one plant in each plot. The remaining plant in each plot was left untreated. Fungicides were applied at the above intervals with a hand wand with a TX-8 nozzle to run-off using a tractormounted sprayer from 30 Apr to 1 Oct. Black spot and Cercospora leaf spot incidence was visually rated using a modified 1 to 10 Florida peanut leaf spot rating scale where 1= no disease, 2 = very few lesions in canopy, 3 = few lesions noticed in lower and upper canopy, 4 = some leaf spotting and <= 10% defoliation, 5 = lesionsnoticeable and <= 25% defoliation, 6 = lesions numerous and <= 50% defoliation, 7 = lesions very numerous and <= 75% defoliation, 8 = numerous lesions on few remaining leaves and <=90% defoliation, 9 = very few remainingleaves covered with lesions and <= 95% defoliation, and 10 = plants defoliated on 19 Jun, 22 Jul, 21 Aug, 24 Sep, and 11 Nov. Significance of treatment effects were tested by analysis of variance and Fisher’s protected leastsignificant difference (LDS) test (P<=0.05).