Evaluating seed treatment and in-furrow treatments for control of potato common scab in Wisconsin

摘要

A trial was established 29 May at the Langlade County Research Area, Antigo, WI, to evaluate fungicide efficacy for control of potato common scab. Approximately 2 oz seedpieces were cut mechanically on 15 May from US#1 Yukon Gold tubers. Seedpieces healed for 7 days before planting. A randomized complete block design with four replications was used for the trial and treatment plots consisted of four 24-ft-long rows spaced 36 in. apart with 12 in. spacing in the row. In-furrow treatments were appliedthe day of planting using a CO2 backpack sprayer equipped with a single TeeJet 8002VS flat fan nozzle calibrated to deliver 12 gal/A at a boom pressure of 40 psi. Seed treatments were applied to cut seed prior to planting using same sprayer equipment aspreviously described. Treated seedpieces were allowed to dry thoroughly before planting. After planting and in-furrow treatments, furrows were mechanically covered using hilling disks. The soil type was Antigo silt loam and fertility, insects, weeds, andfoliar diseases were maintained during the growing season according to standard grower practices for the region. To minimize soil compaction and damage to plants in rows used for foliar and yield evaluation, drive rows for pesticide application equipment were placed adjacent to plots. Seed emergence data were collected 21 June from 10 linear feet of each of the center 2 rows of each plot. Vines were chemically killed with Reglone 1.0 pt/acre on 16 and 23 Sep 2013. The center two rows of each plot wereharvested 30 Sep 2013. Tubers were graded into marketable (US#1), undersize, and cull categories on the day of harvest. After undersize tubers were graded out and tubers washed, but before scabbed tubers are removed, 20 tubers from each plot were chosenarbitrarily and assessed for scab incidence and severity. Disease severity was rated on a scale of 0-3 with 0=no disease, 1=<10% surface area symptomatic, 2=10-25%, 3=>25%, and an average tuber severity was calculated. Data were analyzed using ANOVA (a=0.05) and Fisher's LSD atalpha=0.05.