Experiments were conducted during 2003 and 2004 to determine if peanut yield and market quality factors differed when paraquat was applied 24 to 28 days after emergence or when 2,4-DB was applied in mid August when peanut was seeded during the early, mid-, and late May and during early June.In other experiments conducted from 2003-2004, peanut was planted with or without aldicarb in the seed furrow to control tobacco thrips (Frankliniella fusca Hinds).In a final set of experiments conducted during 2005, treatments consisted of seeding with or without aldicarb followed by no paraquat or paraquat applied 24 to 28 days after emergence.Peanut yield and percentages of extra large kernels, total sound mature kernels, and farmer stock fancy pods were affected by planting date and pesticide treatment independently.Pod yield was higher in one of two years when peanut was planted in early and mid May compared with late May and June planting.In the other year peanut yield was higher when seeded in mid-May compared to early or late May or early June.In three of nine experiments failure to control tobacco thrips by not applying aldciarb reduced pod yield.In five experiments pod mesocarp color was used to determine if damage form tobacco thrips or paraquat delayed pod development and maturation.No differences in percentages of pods considered ready for digging were noted even though significant tobacco thrips damage and injury from paraquat was observed early in the season.A number of differences in canopy reflectance were noted when hyperspectral imaging was used within 1 wk of digging and inverting vines but were not associated with pod maturation.Further research was conducted in North Carolina from 2003-2005 to determine if reflectance of the peanut canopy could be used as an indicator of pod maturation.The cultivars VA 98R and NC-V 11 were planted beginning in early May through early June during each year and reflectance was measured in mid- to late September and was compared with the percentage of pods in the brown and black mesocarp color.The cultivars Gregory and NC 12C were dug weekly beginning in mid September through mid October.Reflectance was determined at two dates spaced approximately 2 weeks apart for the cultivar Gregory.Experiments were also conducted to determine differences in reflectance of the cultivars Gregory and Georgia Green and to determine if reflectance differed when comparing the cultivars VA 98R and Perry seeded in single and twin row planting patterns.Pod yield was affected by planting date with optimum yield occurring when peanut was planted in mid-May.Although pod yield differed among experiments, percentages of extra large kernels (%ELK) and total sound mature kernels (%TSMK) increased as digging was delayed.Pod yield of the cultivars Georgia Green and Gregory was similar in 4 of 6 experiments; yield of Georgia Green exceeded that of Gregory in two experiments.Planting peanut in twin rows resulted in higher yields than planting in single rows regardless of year or cultivar.Reflectance differed in only 1 of 3 years for the cultivar VA 98R and in no years for the cultivar NC-V 11 even though the percentage of mature pods ranged from 15 to 69% when assessed in mid- to late September.Differences in reflectance were noted when comparing the cultivars Gregory and Georgia Green but not the cultivars VA 98R and Perry.Reflectance did not differ when comparing row patterns. Research was conducted during 2004 and 2005 to develop spectral signatures of peanut with visual symptoms of nitrogen (N) deficiency, injury from a combination of low pH and Zinc (Zn) toxicity, drought stress, early leaf spot (Cercospora arachidicola Hori) and web blotch (Phoma arachidicola Marasas et al.) lesions, and following application of acifluorfen, bentazon, clethodim, imazapic, paraquat, and 2,4-DB.Each of the studies showed some differences in spectral reflectance.However, it was difficult to distinguish the herbicide treated plants from the nutrient- and drought-stressed plants due to the similarities in spectral characteristics. Research was conducted in North Carolina during 2003, 2004, and 2005 to determine the relationship between canopy defoliation and peanut yield.Applying fungicides bi-weekly beginning in early July through mid September resulted in less canopy defoliation than applying only two sprays in July or not applying fungicide and in many instances increased pod yield.When peanut canopy defoliation exceeded approximately 50%, digging 6 to 12 days prior to projected optimum maturity resulted in higher yields than digging at optimum maturity.However, response to early digging was variable when defoliation at the early digging date was less than approximately 50%.
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Potential Use of Hyperspectral and Multispectral Remote Sensing Imagery to Enhance Management of Peanut (Arachis hypogaea L.)