Disease susceptibility of 11 hard-cider apple cultivars in southeastern New York, 2006-2007

摘要

Eleven European cider apple cultivars were planted in spring of 2003. All trees were propagated on M.9 rootstock (Nic.29 strain), and trees were trained as a slender spindle using conduit posts supported by a wire that connected the posts 6 ft above ground. Trees were planted 7 ft apart within rows in a randomized block design with six single-tree replications for each cultivar. Trees were evaluated for susceptibility to diseases in 2006 and 2007. In 2006, trees were maintained with standard insecticide and herbicide applications, but no fungicides were applied at any time during the year. Incidence of apple scab and cedar apple rust on leaves was evaluated during summer. All fruit (regardless of maturity) was harvested on 6 Sep 06, moved to cold storage, and then evaluated for fruit decays in mid-November. In 2007, trees were again maintained with standard insecticides and herbicides, but they also received the following fungicide sprays (expressed as rates/A): 21 Apr – Dithane 75DF 3 lb; 1 May – Penncozeb 75DF 3 lb plus Nova 40WSB 5 oz; 10 May – Dithane 75DF 3 lb plus Nova 40WSB 5 oz; 17 May (full bloom) – Dithane 75DF 3 lb plus Topsin M 70WSB 6 oz; 26 May (petal fall) — Dithane 75DF 3 lb plus Flint 50WDG 2 oz; 5 Jun – Dithane 75DF 3 lb plus Topsin M 70WDG 12 oz; 21 Jun – Flint 50WDG 2 oz; 7 Jul – Topsin M 70WDG 15 oz plus Captan 80WDG 36 oz; 21 Jul – Topsin M 70WDG 12 oz plus Captan 80WDG 36 oz; 11 Aug – Topsin M 70WDG 8 oz plus Captan 80WDG 24 oz. (All of these cider apple cultivarsbegin growth later in spring than conventional apple cultivars and bloom 10 to 15 days after other cultivars.) All of the sprays were applied with a Rears three-point-hitch airblast sprayer calibrated to apply 100 gal of spray solution per acre. The fungicide sprays provided excellent control of foliar diseases in 2007, and therefore we did not evaluate disease incidence on leaves. However, fruit were harvested for evaluation in 2007 at the time that the first mature fruit were noted on the ground. Harvest dates are shown in Table 2.All of the apple cultivars were relatively resistant to apple scab infections on both leaves and fruit (Table 1).