Evaluation of selected fungicides for control of foliar diseases of soybean in Kentucky, 2009.

摘要

A conventionally tilled, non-irrigated soybean fungicide trial was planted following corn 20 May at the University of Kentucky Research and Education Center in Princeton, KY. The soil type was Crider silt loam. Plots consisted of 6 rows, 20 ft long, with a between-row spacing of 15 in. and a seeding rate of 11.7 seeds/ft. Treatments were arranged in a randomized complete-block design with five replications. A 12 ft alley separated blocks. Weeds were controlled by applying 32 fl oz/A Round-up herbicide on 7 Jul. Fungicide treatments were applied as a foliar spray on the following dates (reproductive growth stages): 24 Jul (R3) and 14 Aug (R5.5). Fungicide sprays were applied using a CO2-pressurized hand-held sprayer fitted with 6 nozzles containing Lurmark 02F80 spray tips, delivering 15 gal/A at 50 psi. Brown spot severity was assessed 14 Sep by arbitrarily selecting 10 leaves from the center two rows the upper part of the soybean canopy of each plot and visually estimating the percentage of leaflet area affected. The extent of leaf defoliation within each plot was measured on 21 Sep by using a LI-COR (LI-2000) plant canopy analyzer. The center four rows in each six-row plot (16 ft length) were harvested on 19 Oct using a Wintersteiger Delta plotcombine. Yields were adjusted to standard moisture content and were based on a 60 lb/bu test weight.