Southern Runner Research Articles

Evaluation of Runner Peanut Cultivars and Advanced Georgia Breeding Lines for Yield and Resistance to Late Leaf Spot Under Three Disease-Management Programs1

Abstract Podyield and resistance to late leaf spot, caused by Cercosporidium personatum (Berk. & M.A. Curtis) Deighton, were evaluated on nine advanced Georgia breeding lines and five cultivars of peanut (Arachis hypogaea L.): Florunner, Georgia Runner, GK-7, Southern Runner, and Sunrunner. Peanuts were grown at Tifton, GA during 1987-1988 under three leaf spot programs using diniconazole at 0.14 kg/ha with Agri-Dex® (0.5% v/v): 1) unsprayed, 2) 28-day, and 3) 14-day spray schedule. Final disease ratings (Florida 1 to 10 scale) were made approximately 1-wk prior to harvest. In unsprayed plots, Southern Runner and GaT-2566 had significantly lower leaf spot disease ratings than Florunner, GK-7, Sunrunner, and Georgia Runner. Across all fungicide treatments, yields of Georgia Runner averaged significantly higher than the four other cultivars and GaT-2566. Average yields were 5111, 4497, 4433, 4404, 4377, and 4022 kg/ha for Georgia Runner, Southern Runner, GK-7, GaT-2566, Sunrunner, and Florunner, respectively. In addition to low yield potential of GaT-2566, it was susceptible to Rhizoctonia limb rot (R. solani Kühn, anastomosis group 4). However, Georgia Runner was found to have moderate tolerance to late leaf spot and excellent yield potential.

Effect of New Peanut Cultivar Georgia Browne on Epidemics of Spotted Wilt

Epidemics of spotted wilt, caused by tomato spotted wilt tospovirus, were monitored in plantings of groundnut cultivars Georgia Browne, Southern Runner and Florunner in 5 tests during 1990-93 at Attapulgus, Georgia, USA, and in plantings of the 3 cultivars plus Marc I and AT-127 in 3 tests in Colquitt County, Georgia, in 1993. Final incidence of spotted wilt and area under the disease progress curve values for Georgia Browne were similar to those for Southern Runner but lower than those for Florunner, Marc I and At-127. Pod yields for Georgia Browne were higher than those for Florunner in all tests at both locations and higher than those for the 4 other cultivars in Colquitt County in 1993. Pod yields were similar for Georgia Browne and Southern Runner in 5 tests in Attapulgus. Numbers of tobacco thrips (Frankliniella fusca), western flower thrips (F. occidentalis) or larvae of undifferentiated Frankliniella spp. that colonized the cultivars were similar in most cases. Differences among the cultivars in incidence of spotted wilt could not be attributed to differences in thrips population.

Spotted Wilt Apparent Disease Progress in the Component Lines of Southern Runner Cultivar

Abstract The apparent disease progress of spotted wilt, caused by tomato spotted wilt virus, was monitored in the three component lines of Southern Runner peanut (Arachis hypogaea L.), and in cultivars Southern Runner, Florunner and GK-7 in the field in 1990-1992. In all three years, final incidence and area under the disease progress curves were similar among Southern Runner and all three component lines. Final incidence of spotted wilt in Southern Runner and all component lines was less than for Florunner in all three years. AUDPC values were lower in Southern Runner and two of the three component lines than in Florunner. Incidence and AUDPC of spotted wilt in GK-7 was intermediate between Florunner and Southern Runner and its individual components. Disease increase was linear in all component lines and cultivars. Rate of disease progress was similar among Southern Runner and the three component lines. Disease progressed more slowly in Southern Runner and the component lines than in Florunner.

Effect of Dinitroaniline Herbicides upon Yield and Grade of Five Runner Cultivars1

Abstract Five runner peanut (Arachis hypogaea L.) cultivars were treated with four dinitroaniline herbicide treatments or a postemergence herbicide treatment to determine the effect on pod yield and grade, percentage sound mature kernels + sound splits (SMK+SS). No yield differences due to the dinitroaniline herbicide treatments were noted in the three year study. Southern Runner and GK-7 were higher in yield in one of the three test years, however, no cultivar yield differences were noted in the other two years. Grades were lower with pendimethalin in the three years; grades of trifluralin, ethalfluralin and benefin-treated peanuts were variable from year to year.

White Mold and Rhizoctonia Limb Rot Resistance among Advanced Georgia Peanut Breeding Lines1

Abstract Sclerotium rolfsii Sacc. and Rhizoctonia solani Kuhn are soilborne pathogens causing two major diseases in peanut (Arachis hypogaea L.) production: white mold and limb rot, respectively. Chemical and cultural control has been relatively ineffective in the past, consequently disease resistance is actively being sought as an environmentally safer and cost efficient alternative. Seven advanced breeding lines were evaluated from the Georgia Peanut Breeding Program and compared to four commercial runner cultivars. Among the cultivars, Southern Runner was found to have the highest yield and resistance to white mold but not limb rot. GA T-2741 had the best overall yield and disease resistance to both white mold and Rhizoctonia limb rot of all cultivars and breeding lines.

Peanut Production in Systems Restricting Use of Pesticides Based on Carcinogenicity or Leachability1

Abstract This research was conducted to determine the short-term impact of potential broad sweeping changes in pesticide registrations on peanut production and to compare and improve pest management systems for peanuts. In this research, detailed records on production inputs and returns were kept to access the short-term economic impact of each of six production systems differing in pesticide use. The preventative management strategy required additional pesticide inputs and averaged $180 per hectare less return when compared to the non-restrictive IPM program. When non-restrictive IPM programs were compared to IPM systems that eliminated carcinogens, return to management per hectare declined $1010 and $516 for the cultivars Florunner and Southern Runner respectively. The exclusion of the fungicide chlorothalonil was the primary reason for this loss in revenue. Elimination of compounds most likely to leach, based on their relative leaching potential, had minimal impact on peanut production. All test locations had low nematode pressures. The organic production strategy had the highest pre-harvest variable costs, due to the high input of hand labor required for weeding. To produce returns similar to an unrestricted IPM system, a raw agricultural commodity price 1.95 times that of the IPM system would have to be offered to organic growers.

Fatty Acid Composition, Mineral Content, and Flavor Quality of Southern Runner Peanuts Treated With Herbicides and Fungicides1

Abstract The application of herbicides and fungicides (chemical compounds used to control weed and fungal pests, respectively) generally improve peanut yield and grade, however their effect on peanut composition and flavor quality is not well documented. The effects of herbicides or fungicides and their combinations on mineral content, fatty acid composition and flavor quality of Southern Runner peanut were investigated. Fungicide application [chlorothalonil (C) and diniconazole (D)] alone or in combination, improved the yield. Application of most herbicides or fungicides or their combination decreased the long chain saturated fatty acid, eicosenoic acid (20:1), acetone, methyl pyrrole and hexanal content while increasing pyrazine content. Application of imazquin (I) and most of the combinations increased magnesium (Mg) while decreased zinc (Zn) content. Application of benefin (B), metolachor (M), alachlor (A), (B+V), (M+C), and (M+D) increased the oleic linoleic acid (O/L) ratio which should improve the stability of the peanuts. Application of (B+V+A) decreased the flavor intensity of the roasted peanuts. Application of pesticides affected fatty acid composition and flavor quality of Southern Runner peanuts.

Tocopherols in runner and virginia peanut cultivars at various maturity stages

Alpha‐, beta‐, gamma‐, and delta‐tocopherol (α‐T, β‐T, γ‐T and σ‐T) were determined in peanut (Arachis hypogaea L.) cultivars Florunner, Sunrunner, Southern Runner, AT‐127, GK‐7, NC‐7, NC‐9 and GK‐3. There were significant differences in tocopherol content among runner‐ and virginia‐type peanut cultivars, and these differences were affected by the degree of maturation. α‐T decreased with maturation for all of the cultivars except Florunner. γ‐T increased with maturation for GK‐7, NC‐9 and GK‐3 but decreased for Florunner. For the mature nuts, Florunner and NC‐9 had the highest levels of α‐T while GK‐3 and Southern Runner had the lowest levels. GK‐7 and Sunrunner had the highest levels of γ‐T, while the lowest levels were in Florunner and GK‐3.

Cuticular lipids from wild and cultivated peanuts and the relative resistance of these peanut species to fall armyworm and thrips

Cuticular lipids were extracted from blooms and foliage of the peanut cultivar Arachis hypogaea L. (Southern Runner) and identified by gas chromatography-mass spectrometry. The major components of the bloom surface lipids were n-alkanes, aldehydes, and fatty acids, while fatty alcohols, fatty acids, and n-alkanes were the major components of the foliage lipids. Cuticular lipids of the foliage from five wild peanut species, A. glandulifera, A. batizocoi, A. ipaensis, A. chacoense, and A. paraguariensis differed in composition. Each wild peanut species was more resistant to fall armyworm, Spodoptera frugiperda, than the cultivar was, and each suffered less thrips damage than the cultivar did

Comparative Response of Three Peanut Cultivars To Multiple Herbicide Applications1

Abstract Field studies in 1990 and 1991 at Tifton, GA and Gainesville, FL evaluated the response of Florunner, Southern Runner, and NC 7 peanut to multiple herbicide applications. A split-split plot experimental design was used with peanut cultivars as main plots. Sub-plots were four levels of chloroacetamide herbicides applied sequentially preplant incorporated and at vegetative emergence. Sub-subplots were five postemergence herbicide treatments. All herbicides were applied at registered rates and times of application. There were no interactions between cultivars, choloracetamide, and/or postemergence herbicides for canopy width, yield, and grade of peanut. There were no interactions between chloroacetamide and postemergence herbicides for the same parameters. Main effects were the only sources of significant (P = 0.05) differences in the data. Based on these results, unusual precautions in using these herbicide combinations on these cultivars are not needed.

Chemigation and Ground-Spray Applications of Cyproconazole for Control of Late Leaf Spot of Peanut

In field experiments conducted during 1990 and 1991, chemigation applications of biosynthesis inhibiting fungicide cyproconazole (0.112 kg a.i./ha) were equal to or bether than ground-spray applications of cyproconazole or chlorothalonil (1.26 kg a.i./ha) late leaf spot, caused by Cercosporidium personatum, on peanut (Arachis hypogae) cultivars Florunner and Southern Runner. Late-season leaf spot epidemics and resulting defoliation were severe in nontreated plots in both years. All fungicide treatments provided similar levels of control in 1990 (.)

Supplemental Calcium Application on Yield, Grade, and Seed Quality of Runner Peanut

AbstractThe need for supplemental Ca continues to be the most likely nutritional problem of peanut (Arachis hypogaea L.) production on acid, sandy, and low cation exchange capacity (CEC) soils. The need for supplemental Ca from gypsum for improved yield, quality, and seed germination of four runner‐type cultivars was evaluated on 14 sites with a range in available soil Ca of 48 to 242 mg kg−1 during 1987 to 1989. Yields of all four cultivars were increased by addition of gypsum at the five sites with the lowest Mehlich‐1 extractable Ca (< 158 mg kg−1), although the magnitude of response varied among cultivars. Increases in sound mature kernal occurred for GK 7 and Southern Runner at soil Ca levels higher than that required for maximum yield. Calcium composition of nuts also was affected more by supplemental gypsum than was either yield or SMK. Germination percentage and seedling survival were both highly correlated with seed‐Ca concentration. Minimum seed Ca needed for maximum germination ranged between 368 and 414 mg kg−1 for the four cultivars. Comparable Ca values for seedling survival ranged between 361 and 445 mg kg −1. The correlations between soil Ca and either germination or seedling vigor were less than those between seed Ca and germination or seedling vigor. All correlations involving Ca and germination suggest that soils used to produce seed, probably need a higher level of available Ca than those used for general production.

Resistance to Cercosporidium Personatum Within Peanut Germplasm1

Abstract Late leafspot, caused by Cercosporidium personatum, is prevalent in the southeastern United States and causes extensive defoliation and peanut yield losses if fungicides are not applied. Some sources of resistance to late leafspot have already been identified in the United States peanut germplasm collection. In screening 500 peanut plant introductions from the Southern Regional Plant Introduction Station, Experiment, Georgia, 33 genotypes with partial resistance to C. personatum were identified. These lines were evaluated for leafspot resistance and yield without fungicide protection from 1989 through 1991. Although PI 215695, PI 215696 and PI 215724 were significantly more resistant than all other genotypes over the three years, pod yields were low. During years of high disease severity, resistant selections PI 203396 and PI 162529 had the highest yields. Significant positive correlation occurred between late leafspot ratings and shelling percentage (r = 0.43 and 0.47) in 1990 and 1991. Evaluation of the main-stems of plants during the growing season revealed that the three most resistant genotypes had significantly less defoliation than Southern Runner, the only cultivar grown with resistance to late leafspot. There are important genes for resistance present in the United States peanut germplasm collection and there is a need for evaluation of the entire collection for useful resistance to leafspot and other pests.

Single Leaf Carbon Exchange and Canopy Radiation Use Efficiency of Four Peanut Cultivars1

Abstract Knowledge of the interception of solar radiation by crop canopies and the use of that radiation for carbon assimilation is essential for understanding crop growth and yield as a function of the environment. A field experiment was conducted in 1990 at Gainesville, FL to determine if differences in single leaf carbon exchange rate (CER), canopy radiation interception, radiation use efficiency (g dry matter produced per unit of solar radiation intercepted), and increase in seed harvest index with time exist among several commonly grown peanut (Arachis hypogaea L.) cultivars. Four cultivars (Early Bunch, Florunner, Marc I, and Southern Runner) were grown in field plots on a Kendrick fine sand (a loamy, siliceous, hyperthermic Arenic Paleudult) under fully irrigated, intensive management. Total crop and seed dry matter accumulation were determined, and canopy radiation interception measured at weekly intervals. CER of uppermost, fully expanded sunlit leaves were determined at midday at 2-wk intervals. Single leaf CER's were similar among cultivars (25 to 35 μmol CO2 m-2 s-1) and relatively stable throughout most of the season, before declining during late seed filling. Although interception of radiation differed somewhat among cultivars during early canopy development, total crop dry matter accumulation was linearly related to the cumulative amount of radiation intercepted by all four cultivars (r2=≥0.99). Radiation use efficiency was similar among all cultivars with a mean of 1.00 g dry matter accumulated per MJ of intercepted solar radiation. The increase in seed harvest index with time was linear (r2≤0.94) and the rates of increase were similar among the Early Bunch, Florunner, and Marc I cultivars (0.0058 d-1), but lower (0.0043 d-1) for the later maturing Southern Runner cultivar. Results from this study indicated that the primary differences among these four cultivars were in early-season development of the leaf canopy and resultant radiation interception and the rate of seed growth, rather than the capacity to assimilate carbon dioxide.

The Effects of Chemical Treatment, Harvest Date, and Specific Isolation Media on the Peanut Shell Mycobiota of Two Peanut Cultivars

Peanut (Arachis hypogaea) cultivars Florunner and Southern Runner grown at two locations near Tifton, Georgia, were either treated with the fungicide flutolanil (Moncut) or nontreated. Comparisons of peanut shell mycobiota were made for both treatments at two harvest dates. A total of 12,744 fungal isolates were cultured from 4,200 shells assayed. Over two-thirds of the isolates were Deuteromycotina. Common form-genera isolated were Alternaria, Curvularia, Fusarium, Lasiodiplodia, Nigrospora, Rhizoctonia, and Rhizopus. Isolations of some genera were significantly different between treatments within a cultivar, and between the two cultivars. However, these differences were of small magnitude and inconsistent across farms, harvest dates, or cultivars

Use of a resistant peanut cultivar with copper fungicides and reduced fungicide applications for control of late leaf spot

In field tests conducted in 1988 and 1989, chlorothalonil, propiconazole, or diniconazole applied on a 21-day schedule provided control of late leaf spot ( Cercosporidium personatum) of peanut ( Arachis hypogaea) that was sufficient to prevent yield losses in Southern Runner, a cultivar with moderate resistance to C. personatum. Copper hydroxide in 1988 and 1989, copper oxysulphate in 1988 and copper resinate fungicides in 1989 applied in a 14-day schedule produced yields comparable to chlorothalonil applied in a 14-day schedule, although leaf spot control provided by all of these materials was inferior to that provided by chlorothalonil, propiconazole or diniconazole. In 1990, significant yield loss due to leaf spot did not occur for even the untreated plots. In 1988 and 1989, highest yields were from plots treated with diniconazole, primarily because of superior control of soil-borne diseases by this fungicide.

Response of Florunner and Southern Runner Peanut Cultivars to Chemical Management of Late Leaf Spot, Southern Stem Rot, and Nematodes

A field experiment was conducted in 1989 and 1990 to study the effects of chlorothalonil, flutolanil, and aldicarb, singularly and in combination, on late leaf spot, caused by Cercosporidium personatum, southern stem rot, caused by Sclerotium rolfsii, and root-knot nematodes, Meloidogyne arenaria, on Florunner and Southern Runner peanut (Arachis hypogaea) cultivars. In a split-plot experiment, Florunner and Southern Runner were treated with chlorothalonil at 0, 0.6, or 1.2 kg a.i./ha; flutolanil at 0 or 2.2 kg a.i./ha; and aldicarb at 0 or 3.4 kg a.i./ha. Southern stem rot and nematode pressure were severe in both years, and late leaf spot was severe in 1989. Leaf spot was more severe in Florunner than in Southern Runner in control plots both years and in plots receiving the low rate of chlorothalonil in 1990. In both years, the high rate of chlorothalonil reduced late leaf spot severity more than the low rate. Aldicarb and flutolanil did not affect late leaf spot severity. Flutolanil and aldicarb reduced the incidence of southern stem rot in both cultivars in both years, but flutolanil was more effective than aldicarb. Chlorothalonil had little or no effect on incidence of southern stem rot, and both cultivars were equally susceptible. Aldicarb reduced root-gall indices in both years, but no effects were attributable to cultivar or fungicide. Yields for the two cultivars were not different. In both cultivars, effects of chlorothalonil, flutolanil, and aldicarb were additive on yield increases for both years

Disease Progress of Spotted Wilt in Peanut Cultivars Florunner and Southern Runner

Early season abundance of tobacco thrips (Frankliniella fusca) and incidence and disease progress of spotted wilt, caused by tomato spotted wilt virus (TSWV), were compared in Florunner and Southern Runner peanut (Arachis hypogaea) cultivars in field studies in 1989-1991. In replicated plot experiments and large field quadrat studies, populations of tobacco thrips adults and thrips larvae were similar for the two cultivars. in 1989 and 1991, cultivar, time, and cultivar × time interaction effects on incidence of spotted wilt were significant in all replicated plot studies except one (...)

Variation in Yield and Resistance to Southern Stem Rot Among Peanut (Arachis hypogaea L.) Lines Selected for Pythium Pod Rot Resistance1

Abstract Five Spanish and seven runner peanut (Arachis hypogaea L.) genotypes and five check cultivars were compared for southern blight susceptibility on heavily Sclerotium rolfsii-infested soil. Inoculum density of S. rolfsii at the test site was enhanced by continuous years of residue management. The genotypes derived from crosses with PI 365553 and PI 475871 were selected based on reaction to Pythium pod rot and agronomic performance. Variation for southern blight incidence occurred among lines in both runner and Spanish genotypes. Disease incidence was lower in four runner genotypes, Southern Runner, and TxAG-3 than in Okrun and Florunner. Significantly (p=.05) less disease occurred in one breeding line, Tx855138, than in other Spanish entries. Three-year average yields of runner genotypes ranged to 25% higher than runner cultivars, while Tx855138 averaged 50% higher in yield than Tamnut 74. Over entries, the coefficients of correlation for yield and southern blight incidence, and southern blight incidence and disease discolored pods were not statistically significant.

Combining Center Pivot Irrigation Applications of Chlorothalonil with a Moderately Resistant Cultivar for Control of Late Leaf Spot in Peanut

The efficacy of center pivot irrigation applications (chemigation) of chlorothalonil at recommended rates (1.25 kg a.i/ha) was less than with conventional, ground spray applications for control of late leaf spot (Cercosporidium personatum) in Florunner (susceptible) and Southern Runner (moderately resistant) peanut (Arachis hypogaea) cultivars in 1989 and 1990. Final leaf spot ratings in chemigated plots of Florunner were lower (P≤0.05) than those in untreated plots in both years and in 1989 were higher (P≤0.05) than ratings of unsprayed plots of Southern Runner (...)