Efficacy of foliar fungicides in the control of frogeye leaf spot in soybean in Northwest Missouri, 2018

摘要

Fungicides were evaluated for their efficacy in the control of frogeye leaf spot (FLS) in soybean in Northwest Missouri. The trial was conducted in a non-irrigated, no-till field near the campus of Northwest Missouri State University in Nodaway County, MO. Plots were planted on 23 May to the soybean cultivar Pioneer 37T09L at a seeding rate of 143,743 seeds/A. Agronomic management of the plot followed the recommended practices for soybean in Northwest Missouri. The experimental plots consisted of four 27-ft long rows, spaced 30-in. apart. The fungicide treatments were assigned to the experimental units in a randomized complete block design with four replications per treatment. The fungicides were applied at reproductive stages R2 at different application rates, using a CO2 pressurized sprayer equipped with four TeeJet TXVS-10 nozzles, flow rate 15 gal of water/A at 30 psi. Incidence of FLS per plot was determined from five images that were taken over the canopy of the center rows on September 14, keeping the camera's field of view about 30 to 40 cm from the top plant canopy level and at a similar angle between each photo shot. Incidence was calculated as the quotient of number of leaflets showing at least one FLS lesion by the total number of visible leaflets in each photo. A leaflet was regarded as visible if it showed at least 75% of its foliar blade in the photo. Plots were harvested on 28 Oct and yield was adjusted to 13% moisture. Pairwise treatment comparison for FLS and yield were carriedout by an unprotected Fisher's least significant difference (LSD) test.