Evaluation of experimental fungicides for disease control on Loring peach and Redgold nectarine, 2014

摘要

Several fungicides were compared for broad-spectrum disease control on 22-yr-old trees, focusing especially on scab in the petal fall to second cover spray period. The test trees were not treated with fungicides in 2013 to allow the buildup of scab inoculum for 2014. Dilute treatments were applied to the point of run-off (approximately 200 gal/A) with a single nozzle handgun at 350 psi in a randomized block design with four replications as follows: 1 Apr (BS, bud swell); 24 Apr (PF, petal fall); 2 May (SS, shuck split); 1st through 5th covers (1C-5C): 19 May, 6 Jun, 20 Jun, 10 Jul, 24 Jul (3-wk pre-harvest, 3PH); 8 Aug (1-wk pre-harvest, 1PH). Commercial insecticides were applied to the entire test block with an airblast sprayer. Leaf curl incidencewas rated on 50 shoots per tree 27 May. Scab and rusty spot were assessed on 40 fruit on each tree 11 Aug. Samples of 40 apparently rot-free fruit per replicate tree were harvested from both Loring and Redgold on 13 Aug. Fruit were selected for uniformripeness, grouped into 20-fruit subsamples, and placed on fiber trays. One set was misted with de-ionized water, and the other set was inoculated with a suspension of 40,000 M. fructicola conidia/ml. All fruit were incubated in polyethylene bags at ambient temperatures (68-79°F) while rating rot development at the indicated intervals.