Submitted to: American Peanut Research and Education Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 7/17/2006
Publication Date: N/A
Citation: Interpretive Summary: None required.
Technical Abstract: Small-plot, irrigated field trials were conducted at 2 locations in 2005 (Tifton, Dawson) to evaluate the influence of imazapic and 2,4-DB on tomato spotted wilt virus (TSWV) infection, yield, grade, and seed quality of three peanut varieties (Georgia Green, C-99R, GA-01R). A split-plot design (variety X herbicide) with four replications was used at both locations. Each peanut variety was treated with imazapic (0.07 kg ai ha-1) at either 30 or 45 days after planting (DAP) or 2,4-DB (0.28 kg ai ha-1) at either 75 or 90 DAP. Plot areas were maintained weed-free throughout the growing season with a preemergence application of pendimethalin plus diclosulam followed by plowing and/or hoeing as needed. Yield and pod samples were collected using a stationary plot harvester in mid to late-September, depending on variety. Pod samples were segregated and one portion used to determine an official farmer stock grade (total sound mature kernels, TSMK). The remaining pods were shelled and medium seed collected for germination and vigor evaluation. Standard percent germination at 25 C and cold germination (15 C) tests were conducted by the Georgia Department of Agriculture in early-December. All data were subjected to analysis of variance and means separated using Fisher’s Protected LSD Test (P = 0.05). No variety by herbicide interaction was detected. The main effect of variety strongly influenced TSWV infection, yield, grade, germination, and vigor. There were no differences in TSWV infection between Georgia Green and C-99R at Tifton. However, both of these varieties had 45% more TSWV than GA-01R. Variety had no effect on TSWV at Dawson as TSWV infection was extremely low (mean < 1%). GA-01R yielded 5380 kg ha-1 which was greater than C-99R (4800 kg ha-1), both of which yielded greater than Georgia Green (3780 kg ha-1) at Tifton. Yield at this location closely followed TSWV infection rates. At Dawson, Georgia Green produced the highest yields (5210 kg ha-1) and C-99R produced the lowest yields (4230 kg ha-1). GA-01R graded highest at Tifton (TSMK 77%) followed by C-99R (75%) and Georgia Green (73%). At Dawson, variety had no effect on grade with mean TSMK 76%. Seed germination at Tifton was greatest with Georgia Green (93%) and lowest with GA-01R (67%). Both Georgia Green and C-99R had greater germination than GA-01R at Dawson. Cold test results mirrored standard germination results with Georgia Green having highest percent germination at both locations (88%). When compared to the non-treated, the herbicides evaluated in these studies had no effect on TSWV, grade, seed germination, and cold germination. However, the main effect of herbicide was significant for yield at the Dawson location only. A late application of 2,4-DB (95 DAP) produced higher yields than any of the imazapic treatments or 2,4-DB at 75 DAP. First-year results from this series of field studies suggest that the intrinsic differences between varieties influence TSWV infection, yield, grade, and seed germination/vigor greater than the herbicides imazapic and 2,4-DB.