Evaluation of application timing and fungicide efficacy on corn diseases in central Indiana, 2018

摘要

A trial was established at the Purdue Agronomy Center for Research and Education (ACRE) in Tippecanoe County, IN. Plots were 10 ft wide and 30 ft long, consisted of four rows, and the two center rows were used for evaluation. The experiment was a randomized complete block design with four replications. Corn hybrid 'P9998AM' was planted in 30 in. row spacing at a rate of 34,000 seeds/A on 23 May using a John Deere six row planter. Standard grain corn production practices for Indiana were followed. Fungicides were applied on 10 Jul at the V12 growth stage and on 18 Jul at the VT/R1 (tassel expansion/pollination) stage. Fungicide applications were applied using a Lee self-propelled sprayer equipped with a 10 ft boom fitted with six TJ-VS 8002 nozzles spaced 20 in. apart. Air pressure was regulated at 40 psi which delivered 15 gal/A at 3.6 mph. Disease severity was assessed on 28 Aug at the R5 (dent) stage. Disease severity was rated by visually assessing the percentage of symptomatic leaf area of theear leaf on five plants in each plot. Tar spot severity was rated on 14 Sep at the R6 (physiological maturity) stage by visually assessing three ear leaves in each plot. Values for each plot were averaged before analysis. The two center rows of each plotwere harvested with a Kincaid plot combine on 27 Sep and yields were adjusted to 15.5% moisture. Data were subjected to analysis of variance and means were compared using Fisher's Least Significant Difference (LSD; a = 0.05).