Disease reaction and yield response of experimental peanut lines in Southeast Alabama, 2014

摘要

The study site was turned with a moldboard plow on 3 Apr and rows were formed on 12 May with a KMC strip till rig with rolling baskets. Peanut cultivars were planted on 13 May at a rate of approximately 6 seed/ft of row in a field in a fine Dothan sandy loam (OM<1%) soil at the Wiregrass Research and Extension Center in Headland, AL. Gypsum was applied at a rate of 600 lb/ acre in a 14-in. band over the row middle on 9 Jun. A pre-plant incorporated application of 1.0 qt/A of Sonalan + 0.45 oz/A of Strongarm + 1 pt/A Dual Magnum on 25 Apr was followed by a broadcast application of 3 oz/A Valor. Escape weeds were plowed with flat sweeps or pulled by hand. Orthene 97S at 0.6 lb/A was broadcast on 30 May for thrips control. The study site received between 0.4 and 1.0 in. of water on 21 May, 7 Jul, 24 Jul, 29 Jul, 7 Aug, and 25 Aug. Equus 720 6F at 1.5 pt/A was applied on 13 Jun, 27 Jun, 22 Jul, 18 Aug, 2 Sep, while Abound 2.08SC at 18.5 fl oz/A was broadcast on 17 Jul and 4 Aug. Plots consisted of two20-ft rows, spaced 3 ft apart, arranged in a randomized complete block, with four replications. Tomato spotted wilt (TSW) loci counts (1 locus was defined as < 1 ft of consecutive severely TSW-damaged plants per row) were made on 15 Sep. Early and late leaf spot were rated together on 15, Sep, 30 Sep, 7 Oct, and 15 Oct for the early, mid-season, late, and very late maturing cultivars, respectively, using the 1-10 Florida peanut leaf spot scoring system where 1 = no disease, 2 = very few lesions in canopy, 3 = few lesions noticed in lower and upper canopy, 4 = some lesions and < 10% defoliation, 5 = lesions noticeable and < 25% defoliation, 6 = lesions numerous and < 50% defoliation, 7 = lesions very numerous and < 75% defoliation, 8 = numerous lesionson few remaining leaves and <90% defoliation, 9 = very few remaining leaves covered with lesions and < 95% defoliation, and 10 = plants defoliated or dead. Stem rot loci counts (1 locus was defined as < 1 ft of consecutive stem rot damaged plants per row) were made immediately after plot inversion on 25 Sep, 30 Sep, 7 Oct, and 21 Oct for the early, mid-season, late, and very late maturing cultivars, respectively. Plots were combined about 3 to 5 days after inversion. Yields are reported at 7% moisture.Statistical analysis on leaf spot intensity as well as TSW and stem rot incidence was done on rank transformations of data. Non-transformed data are reported. Means were separated using Fisher's protected least significant difference (LSD) test (i><0.05).