Disease reaction of Maturity Group IV conventional soybean cultivars to stem canker in western MS, 2016

摘要

The stem canker (SC) disease ratings of six Maturity Group IV conventional soybean entries were evaluated in field trials conducted in 2016 near Stoneville, MS. A stem canker susceptible cultivar, J77-339, was included as a susceptible check. Soybeancultivars were planted in a Bosket fine sandy loam soil on 5 Jun at a rate of 11 seed/row foot in a randomized complete block design with four replications. Plots were one 40-in. row wide and 10 ft. long. The first 8 plants of each plot were inoculated with Diaporthe aspalathi by inserting infested toothpicks in the upper 1/3 of the stem on 28 Jul when plants were approximately V5 to V6. Disease ratings were conducted on 28 Sep when plants were approximately R6.5 using a modified (0-9) scale based on stem lesion severity. Where a canker did not appear, a rating of 0 (resistant) was assessed. A reaction that produced a visible canker that did not extend up the length of the stem, but stayed in the area of the toothpick received a rating of 1. Dead plants with lesions that extended up most of the plant stem received a score of 9. Disease ratings are reported as the means of four replications. Disease rating data were analyzed using the SAS GLM procedure (Version 9.3, SAS Institute, Cary, NC) and are presented as the mean of eight plants from each plot across the four replicates (n=32 for each entry). Means separation was conducted using Fisher's Protected least significant difference (LSD) at P=0.05.