New fungicides for controlling early-season apple diseases, 2009.

摘要

Treatments were replicated four times in a randomized block design. Each plot contained three trees, one tree of each cultivar, on M.9 rootstocks. Half of the orchard was planted in 1986 and the other half was planted in 1995. Trees in this test blockare spaced 32 ft between sprayed rows, 7.5 ft between trees within rows, and 15 ft between plots within rows. The space between sprayed rows contained either a buffer row of similar apple trees or a buffer row of stone fruit trees. Plots within rows were separated by cedar trees that provided inoculum for rust diseases and minimized drift between plots. Treatments were applied on dates shown in Table 1. Trts 3-6 involved DMI fungicides. Trts 7-9 involved newer fungicides that either contain a QoI fungicide or were applied in a combination with Flint (trifloxystrobin), and these were compared to Flint applied alone (trt 10). Luna Sensation is a package mix of trifloxystrobin and fluopyram. Fontelis (= LEM-17, penthiopyrad) was applied with a half-rateof Flint. Trts 11-12 involved variations in timing of the mildewcide Torino (=GWN-4617, cyflufenamid) that was alternated in trt 12 with Vintage (=GWN-4616, a new formulation of fenarimol). In both trts 11 and 12, Penncozeb was applied at the above-labelrate of 2 lb/100 gal in sprays that extended beyond petal fall so as to ensure that scab and rust diseases would not compromise our ability to evaluate leaves for mildew. The prebloom period was relatively dry with only one significant scab infection period near tight cluster (20-22 Apr, 52 hr wetting, 47° F, 0.85 in. rain). Another major infection period occurred during bloom (3-9 May, 105 hr, 55° F, 1.76 in. rain). A few primary scab lesions were noted on unsprayed trees in an adjoining block on 6May. Abundant primary scab was evident on unsprayed trees by 15 May. There were nine secondary scab infection periods during the latter half of May, 16 in Jun, 13 in Jul, 7 in Aug, and 4 in Sep. June and July were very wet with leaf wetting recorded for50% of total time in June and 37% of total time in July. Inches of rainfall recorded for June and July were 8.45 and 4.71, respectively. Due to the cool weather, scab remained active throughout summer.