Evaluation of bactericide programs for the management of fire blight on ‘Idared’ apples in NY, 2012

摘要

A trial was conducted at the New York State Agricultural Experiment Station in Geneva, NY to evaluate the effectiveness of bactericide programs for the management of blossom blight and shoot blight in an apple orchard. The orchard site is a young planting of 5-yr-old ‘Idared’ trees on B.9 rootstocks. Treatments with foliar applications, designated ‘foliar’, were applied dilute (300 gal/A) to runoff using a handgun or gas powered backpack sprayer (200 PSI). Treatments were made at 10% bloom (Apr 19) 50% bloom (24 Apr), 70% bloom (27 Apr) 80% bloom (30 Apr), and during terminal shoot growth (8 Jun). ‘Idared’ trees were inoculated at full bloom (1 May) with Erwinia amylovora strain Ea 273 at 1x107CFUml-1 using a hand-pumped Solo backpack sprayer.Shoots for the shoot blight treatments were inoculated on 15 Jun by bisecting the two youngest leaves with a pair of scissors dipped in the same inoculum. Blossom blight and shoot blight symptoms were assessed on blossom clusters and terminal shoots on6 Jun and 9 Jul, respectively. The incidence of blossom blight was expressed as the number of blighted blossom clusters out of 100 clusters assessed with 5 replicate trees per treatment. Shoot blight was assessed as the length of canker extending from the site of wounding with 10 shoots assessed for 5 replicate trees. Additional non-inoculated and non-wounded checks (not shown) were included for both blossom blight and shoot blight evaluations to determine a background level of infection. Disease intensity data were subjected to analysis of variance (ANOVA) for a randomized block design using accepted statistical procedures and software (i.e. Mixed Models (MIXED)) procedure of SAS (version 9.3; SAS Institute Inc., Cary, NC). All percentage data were subjected to arcsine square root transformation prior to analysis.