Effects of foliar fungicides and fungicide-insecticide combinations on hail damaged soybean

摘要

Soybean plots were planted at the University of Nebraska South Central Agricultural Laboratory near Clay Center, Nebraska. The experimental area was planted to soybean the previous year and was no-till. Post emergent weed control was carried out through applications of glyphosate at 32 fl oz/A with 2 lb of NH4SO4/A on 27 Jun. Plots were 10 ft (four rows spaced at 30-in.) wide by 18 ft long. Applications were made at R3 growth stage (beginning pod), 7 days after a 3-in. hail/rain event occurred on 2 Aug, which caused plant stem breakage and estimated 50 % defoliation of the plants. The treatments were applied at a rate of 15 gal/A with a CO_2 pressurized sprayer with a 10 ft boom equipped with 6 TeeJet 8002VS nozzle tips at 20-in. spacing. Eleven fungicide and fungicide-insecticide combination treatments and a control (non-treated) were applied to the experimental plots in a randomized complete block design with four replications. Irrigation was applied as needed throughout the growing season. Severity of brown spot (Septoria glycines), canopy greenness (%) and yield were assessed on the two center rows of each plot. Brown spot severity was rated on a 0-100 % scale at 14, 28 and 43 days after treatment application. Percent of canopy still green (0-100%) was assessed at maturity (3 Oct). Plots were harvested on 23 Oct with a Gleaner plot combine model 'K2' equipped with on-board scale and data logger. Mean treatment separation for each measured variable was achieved using Fisher's protected LSD.