Peach disease management with organic fungicides, 2008.

摘要

The test block consisted of a 12-year-old ‘Encore’ peach orchard planted at 25 ft x 25 ft spacing. Treatments were replicated four times in a randomized complete block design with single tree plots. Treatment trees were surrounded on allsides by non-sprayed buffer trees. A Rears Pak-Blast-Plot airblast sprayer calibrated to deliver 100 gal/A at 100 psi traveling at 2.1 mph was used for applications. Treatment applications were made on the following dates and tree growth stages: 3Apr (P, pink); 10 Apr (B, bloom); 18 Apr (PF, petal fall); 30 Apr (SS, shuck split); and 14, 28 May 11, 25 Jun 8, 23 Jul and 6 Aug (1C-7C, 1st through 7th cover). During the ripening period in late August and early September, three pre-harvest spraysfor fruit rot control were applied on 19, 29 Aug and 4 Sep (16, 7, and 1 DPH, days preharvest). Conventional insecticides and miticides were applied as needed to the entire block using a commercial airblast sprayer. Conditions were extremelyfavorable for blossom blight development due to several rainy periods and above average temperatures during pink and bloom. The warm weather and long dry periods from the susceptible stages of PF through 2C were favorable for rusty spotdevelopment. Although rainfall for the growing season was below average, high inoculum levels in the form of twig lesions and several rain periods between SS and 40 days pre-harvest created very favorable conditions for scab. The number of raindays with over 0.10 inch accumulation following each spray were: P, 3: B, 1; PF, 2; SS, 2; 1C, 3; 2C, 3; 3C, 0; 4C, 5; 5C, 1; 6C, 1; 7C, 1. Conditions were unfavorable for brown rot due to the dry weather in August and early September. No rainoccurred after any of the pre-harvest sprays. Trees were overhead irrigated on 25 Aug to promote development of brown rot. Blossom blight was evaluated on 7 Jul by examining 20 fruiting shoots per tree for the presence of cankers. Rusty spot wasevaluated on 24 Jun by examining 40 fruit per tree. Scab was evaluated on 27 Aug by examining 50 fruit per tree. Brown rot, Rhizopus rot, anthracnose rot, and other rots were evaluated on 5 Sep by examining all fruit on four or more branches perreplicate tree; a minimum of 100 fruit/tree were examined. For post harvest evaluations, 40 asymptomatic mature fruit were harvested from each tree and placed on benches in two greenhouses (average air temp = 75.4deg F and 75.6deg F). Fruit werelightly sprayed with water immediately after harvest and the following day to promote rot. Brown rot, Rhizopus rot, and other rots were assessed at 3 and 6 days postharvest (dph).