Evaluation of fungicide programs for control of apple scab and cedar apple rust, 2014

摘要

A trial was conducted at the New York State Agricultural Experiment Station in Geneva, NY to evaluate the effectiveness of fungicide programs for the management of apple scab and cedar apple rust. The orchard site is a mature planting of 16-yr-old trees on MM.111 rootstocks with M.9 interstems interplanted in discrete replicated plots. Each plot consisted of one 'Golden Delicious' tree and another tree where the lower scaffold limbs were 'Mcintosh' and the upper scaffolds were 'Ginger Gold'. Betweeneach tree 10 ft tall cedar trees were planted to reduce inter-plot drift and provide a high level of cedar apple rust disease pressure. Treatments were applied dilute (300 gal/A) to drip using a handgun (250 PSI) at 7-10 day intervals (18 Apr-green tip,25 Apr-half-inch green, 2 May-tight cluster, 9 May-pink; 16 May-late bloom, 23 May-petal fall, 30 May-1st cover, 12 June-2nd cover). Summer cover sprays (3rd through 6th cover) were applied to all programs with a Unigreen Turboteuton Mistblower sprayer (Uni-green Crop Protection, S.p.A., Reggio Emilia, Italy). Apple scab infection events based on Mills predictions using estimated leaf wetness occurred 15 Apr, 29 Apr, 8 May, 22 May, and 9 Jun. Five additional infection events occurred between 3rd and 6thcover. The incidence of apple scab symptoms on 'Mcintosh' was assessed for immature fruit and terminal shoots on 9 Jun, and again on terminal shoots and mature fruit on 19 Aug. The incidence of cedar apple rust symptoms on 'Gingergold' was assessed forterminal shoots on 9 Jun. The incidence of apple scab symptoms on fruit was calculated from the number of fruit with apple scab lesions out of five randomly collected fruit. For each of four treatment replications, 10 such collections were assessed. Theincidence of apple scab and cedar apple rust symptoms on terminal leaves was calculated from the number of terminal leaves with apple scab lesions or cedar apple rust lesions with pycnidia out of eight fully expanded leaves from the distal end of the shoot. For each of four treatment replications, the incidence of 10 shoots was assessed. Disease incidence data were subjected to analysis of variance (ANOVA) for a randomized block design using accepted statistical procedures and software (i.e. GeneralizedLinear Mixed Models (GLIMMIX)) procedure of SAS (version 9.4; SAS Institute Inc., Cary, NC). All percentage data were subjected to arcsine square root transformation prior to analysis.