bluuebunny/crossref_metadata_2025 huggingface dataset:
Temporal and Spatial Distribution of Hormones in Peanut Ovules During Early Development
Authors: Feng Q. L. , Mohapatra S. C. , Pattee H. E. , Stalker H. T.
Published: April 2010

Study of hormonal regulation of fruit development requires quantitative measurement of reproductive tissues at different developmental stages. This study reports the application of ELISA (enzyme-linked immunosorbent assay) for the measurement of free indole-3-acetic acid (IAA), dihydrozeatin riboside (DHZR) and abscisic acid (ABA) in ovules of peanut (Arachis hypogaea L., cv. NC 6). IAA levels in apical and basal ovules gradually increased with aerial peg elongation from 4 to 10 d after pollination (DAP), but decreased when peg elongation ceased by 14 DAP. Higher DHZR levels were observed in aerial ovules at 10 DAP, and the ABA level was highest at 1 DAP. Aerial apical ovules contained higher IAA and DHZR levels than basal ovules. At day 1 after soil penetration (DASP), IAA and ABA levels in both ovules decreased, whereas DHZR levels increased. Peg tip swelling and ovary enlargement at 5 DASP were accompanied by increased levels of all three hormones. The highest levels of the hormones were observed in both ovules at 7 DASP, i.e., when embryos were at the globular stage and ovaries were rapidly enlarging to form pods. Basal ovules also had higher hormonal levels than apical ovules after soil penetration. Progressive changes in hormone levels during peanut ovule and embryo development suggest a physiological relationship between the two events.
The Impact of Tillage Practices on Thrips Injury of Peanut in North Carolina and Virginia1
Authors: Brandenburg R. L. , Herbert D. A. , Sullivan G. A. , Naderman G. C. , Wright S. F.
Published: April 2010

Reduced tillage peanut production is gaining popularity and the impact of this practice on insect pests is not well understood. This study monitored thrips (Frankliniella fusca Hinds) damage and abundance on peanut (Arachis hypogaea L.) in North Carolina and Virginia on peanuts grown under different tillage regimes from 1986-92. A general trend for less thrips damage in reduced tillage plots was consistent in all years except 1992 in North Carolina. In many instances, damage to plants in reduced tillage peanuts was significantly less than in a conventionally tilled system. The implications for future pest management strategies involving reduced pesticide use as well as research needs to meet these goals are discussed.
Effect of Water Stress on Composition of Peanut Leaves
Authors: Ali-Ahmad M. , Basha S. M.
Published: April 2010

Water stress was induced in peanut (Arachis hypogaea L. cv. Marc 1) plants by withholding water for 5 to 20 d. Leaves from the water-stressed plants were analyzed to determine the effect of water stress on amino acids, sugars, protein content, and polypeptide composition of peanut plants. The results showed that the total protein content of the leaves significantly increased when peanut plants were subjected to water stress for 5 to 20 d as compared to irrigated controls. Analysis of the leaf protein by SDS polyacrylamide gel electrophoresis showed higher levels of polypeptides in stressed leaves compared to the control leaves. Peanut leaves from water-stressed plants also showed higher amounts of free amino acids and soluble sugars as compared to the irrigated plants. Thus, water stress enhanced accumulation of proteins, free amino acids, and soluble sugars in the peanut plants.
A Screening Attachment for an Amadas Peanut Combine1
Authors: Blankenship P. D. , White J. W. , Lamb M. C.
Published: April 2010

Some farmers mechanically screen farmer stock (FS) peanuts after combining to remove undesired materials for value and quality improvement. Screening is accomplished with low capacity, portable screens at the field after combining or with high capacity cleaners or screens at buying points. An alternative method for FS peanut screening has been developed cooperatively by Amadas Industries and USDA-ARS, National Peanut Research Laboratory utilizing an experimental combine screening attachment. The attachment is a hydraulically driven, rotating cylindrical screen (trommel) with an axis inclined less than 10° from horizontal during operation. Peanuts are screened with the trommel prior to entering the combine basket, and smaller, unwanted materials are returned to the soil. Thirty-eight lots of FS peanuts averaging 3.27 t/lot were combined throughout all U.S. peanut-producing regions to examine performance. Foreign materials for the screened lots averaged 2.15% less than the unscreened lots (P = 0.05). Hulls were 0.62% less in the screened lots (P = 0.05). None of the other grade factors or market values per hectare were significantly different for runner peanuts. Foreign materials for screened virginia peanuts were 2.44% less than in unscreened (P = 0.01). Loose shelled kernels were 0.44% higher (P = 0.05), hulls 0.67% lower (P = 0.10), and damage 0.56% higher in screened peanuts than in unscreened. None of the other grade factors or market values per hectare were significantly different for Virginia peanuts. Although most grade factors and values per hectare were not significantly different for screened and unscreened peanuts tested, foreign materials were reduced significantly providing needed quality improvement. Possible cleaning costs also could be reduced with the attachment.
Correcting Current Moisture Calculations for Purchasing High Moisture Farmers Stock Peanuts1
Authors: Butts C. L.
Published: April 2010

The U.S. peanut industry may eliminate the 10% moisture content threshold for purchasing peanuts to facilitate implementing continuous flow drying systems and to increase the efficiency of the postharvest processing system. Equations based on the theoretical definition of wet basis moisture content were proposed to determine the weight of various components in a load of farmers stock peanuts. These equations more accurately describe and account for the distribution of moisture within a load of peanuts. Accurate descriptions of the amount of loose shelled kernels, foreign material, and in-shell peanuts would enable improved tracking of losses during storage. Compared to the current price structure, the proposed equations predict reduced payments to growers no more than $30 per 5-mt load of peanuts. The maximum reduction of $30 occurred if peanuts were delivered and marketed at 30% w.b. moisture content. A reduction of approximately $8.50 would occur for a 5-mt load delivered at 15% moisture content. The cumulative economic impact warrants adjustment of the peanut support price schedule if accurate accounting of moisture is implemented.
Yield of Peanut Genotypes Resistant to Root-Knot Nematodes1
Authors: Starr J. L. , Simpson C. E. , Lee T. A.
Published: April 2010

Yields of six runner-, two spanish-, and one virginia-type breeding lines of peanut with resistance to the root-knot nematode, Meloidogyne arenaria, were compared to yields of susceptible cultivars in nematode-infested and noninfested field plots in 1996. Pod yields of resistant runner-, virginia-, and one of the spanish-type breeding lines were 1.5 to 4 times greater (P = 0.05) than pod yields of the susceptible cultivars Florunner, NC-7, and Tamspan 90 in two nematode-infested fields. Final nematode population densities on most resistant breeding lines were lower (P = 0.05) than those on the susceptible cultivars. In the noninfested field, all but one runner- and the two spanish-type resistant breeding lines had pod yields that were not different from that of the susceptible cultivars. Yields of the resistant breeding lines ranged from 3890 to 5152 kg/ha in the noninfested field. In 1997, yields of three of the runner-type breeding lines were compared to the yields of Florunner and Tamrun 96 in three fields not infested with M. arenaria. In one field, no differences were observed in pod yield among the breeding lines and cultivars; in the second field the yield of two of the breeding lines were not different from the susceptible cultivars; and in the third field, only TP259-3-5 had pod yield equivalent to that of the susceptible cultivars. These data indicate that resistant runner-type genotypes with high yield potential have been developed, but additional breeding efforts are needed to develop nematode resistance in high yielding spanish- and virginia-type peanuts.
Application of Direct Solvent Extraction to the LC Quantification of Vitamin E in Peanuts, Peanut Butter, and Selected Nuts
Authors: Lee J. , Landen W. O. , Phillips R. D. , Eitenmiller R. R.
Published: April 2010

Direct solvent extraction with hexane:ethyl acetate (90:10, v/v), saponification, and Soxhlet extraction with hexane were evaluated for their usefulness as extraction methods to determine vitamin E in peanuts and peanut butters. The direct solvent extraction procedure yielded higher values for each tocopherol homolog in peanut and peanut butter compared to the other methods. Coupling of the rapid, direct solvent extraction with normal phase chromatography on Si 60 provides a highly reproducible procedure to quantitate vitamin E in peanuts and peanut products. The overall % recoveries (means ± S.D.) of this study for α-, β-, γ-, and δ-tocopherol were 99.9 ± 3.29, 100.4 ± 11.7, 98.9 ± 5.94, and 100.3 ± 4.87, respectively. Limits of detection and limits of quantitation were 0.21, 0.06, 0.11, and 0.08 ng and 0.39, 0.14, 0.23, and 0.13 ng, respectively, for α-, β-, γ-, and δ-tocopherol. Repeatability, reproducibility, and accuracy of the methods were excellent with % CVs for accuracy of 1.19 (α-T), 1.55 (γ-T), and 2.69 (δ-T). Accuracy was not acceptable for β-T due to its extremely low concentration in the peanut and because peak purity was not obtained for β-T. The method was applied to other seeds with good success. Major homologs were γ-T in peanuts, pecans, cashews, walnuts, and pistachio; α-T in almonds; and α-T3 in macadamia.
Variation in Intensity of Sweet and Bitter Sensory Attributes Across Peanut Genotypes1
Authors: Pattee H. E. , Isleib T. G. , Giesbrecht F. G.
Published: April 2010

Genetic improvement of sweet, bitter and roasted peanut attributes of peanut (Arachis hypogaea L.) flavor is predicated on the existence of genetic variation for the attributes. A total of 1136 SMK samples representing 122 cultivars and breeding lines and 42 year-by-location combinations from three major peanut-producing regions were roasted, ground to paste, and submitted to a trained sensory panel for evaluation of flavor attributes. Data were subjected to analysis of variance to separate genetic, environmental and GxE interaction effects following adjustment for roast color and intensity of the fruity attribute. Genotypic variation was significant for all three attributes as was location-to-location variation within year and region. Large year effects were observed for bitter and roasted peanut attributes. Estimates of broad-sense heritability (H) among inbred lines and cultivars were 0.28 for sweet, 0.06 for bitter, and 0.06 for roasted peanut attributes, indicating that selection for sweetness should result in relatively rapid genetic gain. The ranges of genotypic means were 2.33-4.12 flavor intensity units (fiu) for sweet, 2.43-4.46 fiu for bitter, and 3.75-5.22 fiu for roasted peanut. Correlations among least squares means for the three attributes were highly significant (r = −0.80 for bitter and sweet, r = 0.59 for roasted peanut and sweet, and r = −0.59 for roasted peanut and bitter), indicating that indirect selection based on the more highly heritable sweet attribute could be more effective than direct selection for increased intensity of the roasted peanut and decreased intensity of the bitter attribute. Specific genotypes with superior aspects of roasted peanut flavor were identified.
Quality and Economic Evaluation of Peanut Stored in Modular Containers1
Authors: Wright F. S. , Butts C. L. , Lamb M. C. , Cundiff J. S.
Published: April 2010

Handling problems at buying/drying points have significantly increased with the increased harvesting rate of the 4-, 6-, and 8-row combines. Peanuts (Arachis hypogaea L.) can be cured and dried, stored, and moved to the shelling plant when placed in the modular container (box) at the field location. Boxes sized 1.8 m deep x 2.3 m wide x 7.3 m long will hold about 10 Mg of peanuts with two boxes making a semitrailer load. In 1995 and 1996, standard 4.3-m peanut wagons and 4.3-m boxes were used to study a) changes in peanut moisture, b) handling concerns of boxes, and c) the economic feasibility of handling peanuts in boxes. Peanut moisture content decreased from about 10.3 to 6.2% during the two storage periods of 140 and 160 d. Differences in temperature and relative humidity caused the average moisture content to decrease from 9.6 to 7.5% in 70 d during 1995 compared to a drop from 9.5 to 7.5% in 140 d during 1996. Maximum and minimum temperatures in the top 15 cm lagged behind the ambient temperature by 6.4 and 4.3 hr, respectively. Daily average temperatures and relative humidities in the paired boxes and wagons were similar. Relative humidity in the middle of the boxes and wagons did not fluctuate with ambient humidity. Transferring peanuts by an elevator failed to simulate warehouse system handling damage. The economic analysis, after adjusting for reduced shrink loss and handling loss, showed an on-farm operation cost of $19.54/yr/Mg for the box system concept compared to $19.98/yr/Mg for the current wagon-warehouse system. For a buying point operation, the cost was $9.80/yr/Mg for the box system concept compared to $9.93/yr/Mg for the wagon-warehouse system. The two systems are approximately equal in total cost.
Determination of Peanut Maturity Using a Hunter Colorimeter
Authors: Grimm C. C. , Champagne E. T. , Sanders T. H.
Published: April 2010

Peanut maturity has previously been correlated with the color of the mesocarp of the peanut hull going from light to dark as the peanut matures. In this study, peanuts were sorted into maturity classes of yellow, orange A, orange B, brown and black based on the hull scrape method of Williams and Drexler. The Hunter L*, a*, and b* values were also measured on the dry pods for each class. The color of the mesocarp of freshly harvested peanuts was determined using a Hunter colorimeter. Hunter L*, a*, and b* values on individual peanuts, representative of each class using wet and dry hulls, were reproducibly determined with standard deviations of less than 0.8%. Yellow peanut pods had a median L* value of 70.0, while mature black peanut pods had a median L* value of 51.7 and median values for orange A, orange B and brown pods were, 68.0, 63.7, 57.0, respectively. A similar inverse relationship was observed for the b* value and maturity, while the a* value reached a maximum at orange A. No correlation was observed between the peanut maturity and L*, a*, and b* values acquired with the exocarp intact. Hunter L* and b* values of mesocarps show potential for determining physiological maturity of peanuts.
Peanut Irrigation Management Using EXNUT and MOISNUT Computer Programs1
Authors: Davidson J. I. , Bennett C. T. , Tyson T. W. , Baldwin J. A. , Beasley J. P. , Bader M. J. , Tyson A. W.
Published: April 2010

Economic benefits from irrigating peanuts in the humid Southeast are often marginal or negative because proper consideration must be given to the complex relationships of plant, soil, pest and weather. Computer programs EXNUT and MOISNUT were developed to consider these complex relationships and to recommend timely irrigation of peanuts. A 3-yr study was conducted to evaluate the feasibility of using these computer programs for scheduling peanut irrigation on sandy and medium textured soils in Georgia. During 1994-1996, irrigation was applied two to nine times as recommended by these two computer programs. Net returns to irrigation were $490/ha higher for irrigated plots with these two programs than for nonirrigated plots. Serious compaction problems negated irrigation benefits in 1994 on the medium textured soil, and poor fertility and high disease pressure on the sandy soil negated irrigation benefits in 1995. Without these problems, the average benefit was $920/ha. During 1996, the irrigation benefits from using EXNUT and MOISNUT programs and the fungicide Folicur averaged $1098/ha and $1011/ha for sandy and medium textured soils, respectively. On the average, market grade of the irrigated peanuts were higher than for the nonirrigated peanuts. No aflatoxin (< 1 ppb) was found in edible grade peanuts where these computer programs were used to manage irrigation. Based upon this study and previous research, the EXNUT and MOISNUT computer programs are very useful for scheduling irrigation on peanuts. Proper use of these computer programs should minimize the negative aspects of irrigation for fields with high disease pressure and fields that produce plants with shallow root systems.
Influence of Adjuvants on Efficacy of Imazapic and 2,4-DB
Authors: Jordan D. L.
Published: April 2010

Adjuvants can have a major influence on efficacy of postemergence herbicides. Imazapic and 2,4-DB are applied postemergence in peanut (Arachis hypogaea L.) to control a variety of weeds. Determining how adjuvants influence efficacy of these herbicides could lead to more efficient weed management. Field experiments were conducted during 1997 and 1998 to determine the influence of nonionic surfactant, crop oil concentrate, organosilicone surfactant, and a blend of organosilicone surfactant and methylated seed oil on efficacy of imazapic and 2,4-DB. No-adjuvant and nontreated controls were also included. Adjuvants did not increase redroot pigweed (Amaranthus retroflexus L.) or common cocklebur (Xanthium strumarium L.) control by imazapic. Only minor differences in control of eclipta (Eclipta prostrata L.), entireleaf morningglory (Ipomoea hederacea var. integriuscula Gray), and pitted morningglory (Ipomoea lacunosa L.) by imazapic were noted among adjuvants. Sicklepod [Senna obtusifolia (L.) Erwin and Barneby] and pitted morningglory control increased when 2,4-DB was applied with adjuvants. Common cocklebur control was improved in one of three experiments when adjuvants were applied with 2,4-DB. Redroot pigweed and entireleaf morningglory control by 2,4-DB was not affected by adjuvants.
Physico-Chemical and Sensory Characteristics of Defatted Roasted Peanuts During Storage1
Authors: Brannan G. L. , Koehler P. E. , Ware G. O.
Published: April 2010

Full-fat (53% oil) and defatted (22% oil) blanched, whole, roasted peanuts were stored at 4,25, and 63 C for 12 wk. Defatted peanuts were lighter in color as indicated by a higher Hunter L and b values and a lower a value. The a value which indicated redness also decreased during storage until week 9. Defatting also resulted in roasted peanutty scores that were lower and decreased during storage and decreased pyrazine peak areas (Peaks 24 and 25). Rancidity-related attributes were generally more intense in defatted samples and increased during storage. PV and TBA values were higher in defatted peanuts and increased during storage. A higher moisture content in defatted peanuts may have contributed to its lower storage stability. TBA correlation with rancidity-related attributes indicated secondary oxidation in the samples during storage. The compounds 1-methylpyrrole, 2-methylpyrazine, 2,5 dimethylpyrazine, ethanol, hexanal, and pyridine were tentatively identified by gas chromatography.
Economic Feasibility of Screening Farmer Stock Peanuts Prior to Marketing
Authors: Lamb M. C. , Blankenship P. D.
Published: April 2010

Screening farmer stock peanuts prior to marketing provides a method to increase the per-ton value of peanuts. The mechanical separation of larger, higher value pods (overs) from smaller, lower value pods—which includes foreign material (FM) and loose shelled kernels (LSK) (thrus)—results in significant changes in farmer stock grade. Based on data from 394 runner lots in the Southeast, the percentage of sound mature kernels and sound splits (SMKSS), LSK, FM, and other kernels (OK) was changed by +0.61, −4.31, −2.32, and −0.3 between overs and unscreened lots, respectively. The average value of farmer stock peanuts was $29.15/ Mg higher in the screened lots (overs) compared to the unscreened lots. Although the average per-ton value of screened peanuts is increased, economic feasibility of screening is dependent upon several factors. Two specific marketing scenarios for farmers are analyzed including production of quota poundage only and production in excess of quota poundage where additional peanuts are used to replace peanuts removed during the screening process. Thus, opportunity cost must be included. Typical investment in high capacity (minimum 18 Mg/hr) screening equipment is approximately $150,000. Amortized at 10% rate of interest over a 6-yr period with depreciation allowances and labor and energy cost included, a minimum of 4536 Mg/yr must be screened to effectively ldquo;spread” fixed cost, thus indicating that only exceptionally large farmers, groups of farmers, or buying points have sufficient volume for screening. Further, the quality of peanuts prior to screening also impacts economic feasibility. These factors will be incorporated to estimate probability decision thresholds to determine if individual lots can be profitably screened prior to marketing.
Cold Storage and Tempering of Shelled Peanut1
Authors: Wright F. S. , Butts C. L.
Published: April 2010

The fiberboard box (121×102×124 cm) used to transport and store shelled stock peanuts was compared with an unvented and vented plastic box (121×121×124 cm) for potential condensation during cooling in cold storage (2.5 C and 72% RH) and tempering (20 ± 5 C and 72 ± 20% RH) after removal from cold storage. The boxes held 1000 kg of shelled runner peanuts at about 6.3% w.b. moisture content. In cold storage, the time required for the temperature to change 50% (t50) was 87 and 63% for unvented and vented plastic boxes of the t50 of the fiberboard box, respectively. In the tempering phase, the center peanut temperature began to change after 50 hr in the fiberboard box compared to 19 hr in the vented plastic box. During tempering, the t50 for the unvented and vented plastic boxes were 63 and 36% compared to the fiberboard box. The temperatures in the vented plastic box responded faster to the surrounding conditions and the time for potential condensation to occur in the peanuts was less. These results suggest that a temperature-controlled area for tempering may be needed if the difference between the cold storage and tempering area temperatures is greater than 15 C.
Effects of Postemergence Herbicides on Cercospora arachidicola Hori and Early Leaf Spot of Peanut1
Authors: Baysinger J. A. , Melouk H. A. , Murray D. S.
Published: April 2010

Early leaf spot is a common disease of peanut caused by the fungus Cercospora arachidicola Hori. Experiments were conducted to evaluate the effect of postemergence herbicides on the conidial germination of C. arachidicola and on the incidence of early leaf spot disease in peanut (Arachis hypogaea L.) in a greenhouse. Conidial germination was enhanced (≥ 100%) at concentrations of 1, 100, and 1000 mg/L of 2,4-DB compared with the untreated control. Lactofen reduced conidial germination by 42% compared with the control at concentrations as low as 100 mg/L and completely inhibited germination at concentrations ≥ 5000 mg/L. A concentration of 10,000 mg/L acifluorfen and 2,4-DB completely inhibited conidial germination. Acifluorfen, acifluorfen plus 2,4-DB, and lactofen decreased the sporulation of early leaf spot lesions. Lactofen reduced leaf spot incidence 12% and decreased sporulation of lesions 22% compared with the control. None of the herbicides increased the incidence of early leaf spot on peanut plants or the number of early leaf spot lesions per leaflet when compared with plants that received no herbicide.
Effect of Blanching on Peanut Shelf-Life1
Authors: Sanders T. H. , Adelsberg G. D. , Hendrix K. W. , McMichael R. W.
Published: April 2010

Blanching, seed coat removal, is often a processing step in peanut manufacturing but the general peanut industry consensus is that shelf-life reduction occurs as a result of the process. In order to examine the effects of blanching on shelf-life, runner-type peanuts were blanched using total heating time and final temperature in a 3 × 3 factorial experiment. In each of nine treatments, heating began at 32 C and increased incrementally through six heating zones over a total time of 30,45, or 60 min to a final temperature of either 76.7, 87.8, or 98.9 C. Blanched peanuts from each treatment and nonblanched control samples were stored at 26 ± 1C and ambient RH and were sampled over a 28-wk period. Peroxide value (PV) and oxidative stability index (OSI) of blanched and nonblanched peanuts were similar indicating no meaningful shelf-life differences. Descriptive sensory analysis of peanuts roasted when taken from storage indicated no significant differences in intensity of painty and cardboardy descriptors between blanched and nonblanched peanuts. Mean separations of attributes, including roast peanutty, for which significant differences were noted revealed only a weak, inconsistent relationship between descriptor intensities and final blanching temperature.
Florida Beggarweed (Desmodium tortuosum) and Sicklepod (Senna obtusifolia) Control in Peanut Using Herbicides Applied Through a Wick-Bar1
Authors: Johnson W. C. , Colvin D. L. , Littlefield T. A. , Mullinix B. G.
Published: April 2010

Tall weeds in peanut fields cause losses other that yield reduction from competition by intercepting fungicides and insecticides, and interfering with harvest efficiency. Studies were conducted at Archer, FL and Tifton, GA in 1994 and 1995 to determine an effective means to selectively control tall Florida beggarweed and sicklepod late season in peanut using herbicides applied with a wickbar. Herbicides evaluated were glyphosate, paraquat, and dimethylalkylamine salt of endothall (DMAA endothall); each applied at 0, 25, 50, 75, and 100% by volume. Treatments were applied in two passes at opposite directions midseason at both locations. Glyphosate and paraquat, at concentrations as low as 25% by volume, effectively controlled Florida beggarweed and sicklepod at both locations. DMAA endothall did not adequately control Florida beggarweed or sicklepod at either location, regardless of rate. Peanut yields were not increased by weed control from any herbicide applied with a wick-bar. The only benefits from late-season Florida beggarweed and sicklepod control with a wick-bar appear to be improved fungicide deposition and more efficient mechanical harvest.
Use of Loose Shelled Kernels to Estimate Aflatoxin in Farmers Stock Peanut Lots1
Authors: Whitaker T. B. , Giesbrecht F. G. , Hagler W. M.
Published: April 2010

Loose shelled kernels (LSK) are a defined grade component of farmers stock peanuts and represented, on the average, 33.3% of the total aflatoxin mass and 7.7% of the kernel mass among the 120 farmers stock peanut lots studied. The functional relationship between aflatoxin in LSK taken from 2-kg test samples and the aflatoxin in farmers stock peanut lots was determined to be linear with zero intercept and a slope of 0.297. The correlation between aflatoxin in LSK and aflatoxin in the lot was 0.844 which suggests that LSK taken from large test samples can be used to estimate the aflatoxin concentration in a farmer's lot. Using only LSK allows large test samples to be used to estimate the lot concentration since LSK can be easily screened from a large test sample. If LSK accounts for 7.7% of the lot kernel mass, a 50-kg sample will yield about 3.9 kg of LSK which can be easily prepared for aflatoxin analysis. Increasing the test sample size from 2 to 50 kg reduced the coefficient of variation associated with estimating a lot with 100 parts per billion (ppb) aflatoxin from 114 to 23%, respectively. As an example, a farmers stock aflatoxin sampling plan with dual tolerances (10 and 100 ppb) that classified lots into three categories was evaluated for two test sample sizes (2 and 50 kg). The effect of increasing test sample size from 2 to 50 kg on the number of lots classified into each of the three categories was demonstrated when measuring aflatoxin only in LSK.
Integrated Method of Organizing, Computing, and Deploying Weather-Based Disease Advisories for Selected Peanut Disease
Authors: Bailey J. E.
Published: April 2010

Epidemiological information can be used with weather data to anticipate disease onset. These disease advisories can be applied to reduce the unnecessary use and improve the timing of fungicide sprays. Delivery of weather-based disease advisories to peanut growers in North Carolina was expedited by streamlining programming and information deployment procedures. This approach utilized a standard method of organization of weather data collection and analysis for all diseases, and daily reports were posted to the web. A standardized method of analysis is described which is flexible, and it allows information from epidemiological studies and practical experiences to be integrated to create a specific model for individual diseases. Included is a description of the research and extension activities over a 17-yr period during which weather-monitoring hardware and disease advisories were developed, tested, and utilized for advisories in peanuts at the farm level. Advantages and limitations to this approach with reference to its use in other crops are discussed.
Variation in Aggressiveness and Virulence Among Isolates of Cercospora arachidicola
Authors: Tuggle J. C. , Smith O. D. , Starr J. L.
Published: April 2010

Forty-three isolates of Cercospora arachidicola, incitant of early leaf spot of peanut, were collected from peanut fields in Florida, Georgia, North Carolina, and Texas. Variation in aggressiveness among these isolates using the susceptible peanut cultivar Spanco was examined in greenhouse tests. Variation (P ≤ 0.05) among the isolates was observed for the parameters of incubation period (IP), the reciprocal of the latent period (an estimate of sporulation rate), and number of lesions per leaflet (LN). Additionally, as a group, the isolates from Texas were more aggressive in terms of having a shorter latent period and greater number of lesions per leaflet than isolates from other states. When a subset of eight isolates, which differed in aggressiveness based on IP and LN, were tested on Spanco and three early leaf spotresistant breeding lines (TX957910–5, TX957910–27, TX957910–68), the breeding lines were resistant to all isolates and, except for lesion diameter, no host genotype-by-isolate interaction was detected (P > 0.05). These observations suggest that success of efforts to identify resistance to early leaf spot can be affected by the aggressiveness of the pathogen isolate. Additionally, the resistance of the breeding lines tested is likely to be effective against a wide array of isolates of C. arachidicola.
Antigenic Diversity Among Peanut Stripe Potyvirus (Family Potyviridae) Isolates
Authors: Bhat A. I. , Pappu S. S. , Pappu H. R. , Todd J. W.
Published: April 2010

Several geographically and biologically distinct isolates of peanut stripe Potyvirus (PStV) were tested against available polyclonal and monoclonal antibodies. In direct antigen-coated, enzyme-linked immunosorbent assay (DAC-ELISA), the polyclonal antisera prepared against the purified virus reacted with all the isolates tested. However, a monoclonal antibody, 3AB5, also prepared against the purified virus showed dramatic difference in its reactivity to the same isolates. Tested against blotch isolates from Georgia, Virginia, and Florida, 3AB5 reacted with two of 10 isolates. The reaction was either strongly positive or negative. Antibody 3AB5 did not react with a necrotic strain of PStV from Taiwan. Results indicate the existence of antigenic diversity among PStV isolates.
Modeling Leaf Age-Related Susceptibility and Rust Eruption Dynamics in Peanut
Authors: Wang Z. Z. , Lin K. H.
Published: April 2010

To improve simulation of epidemics of peanut rust, information on the effects of leaf age and pustule eruption dynamics is needed. An analysis was made of the change of leaf susceptibility of rust with leaf aging using plants exposed to field inoculum. The youngest leaf was most susceptible to rust infection. As leaves aged, susceptibility decreased quickly. The relationship of infection frequency (Y, relative number of pustules) to leaf age (X, leaf position downward on the main stem) was described by a mathematical model Y = 2.17X(-0.83). The dynamics of pustule eruption also was studied using artificial inoculation. Analysis showed that after inoculation, pustule eruption over time was distributed in a logistic pattern. Rust eruption began at 130 and reach a peek at 250 rust degree days—that is, between 7 and 15 d after inoculation. Mathematical models of leaf age-related susceptibility and rust eruption dynamics will be incorporated into simulation model of rust epidemics.
Imazapic-Based Herbicide Systems for Peanut and Factors Affecting Activity on Florida Beggarweed
Authors: Wehtje G. , Padgett D. , Martin N. R.
Published: April 2010

Field studies were conducted over 3 yr to evaluate imazapic, applied either alone or combined with other commonly used herbicides for peanut weed control. Imazapic applied early postemergence alone at 71 g/ha provided excellent weed control, maximum yields, and optimum economic returns. Variations of this treatment—such as half rate of imazapic applied alone, tank mixed with other herbicides, or supplemented with other herbicides—frequently had equivalent weed control and yield. However, these variations did not improve economic return. Greenhouse studies evaluated Florida beggarweed control as influenced by weed age, imazapic rate, and application type. The three application types were foliage only, soil only, and soil plus foliage. Control was independent of application type when Florida beggarweed seedlings were less than 20 d old. The soil-only application did not adequately control older seedlings. Foliage-only and foliage plus soil application were equally effective. Averaged across all other factors, imazapic was less effective controlling seedlings older than 20 d. At this age, seedlings produced trifoliate rather than unifoliate leaves. Absorption of 14C-imazapic by unifoliate and trifoliate leaves was equivalent. However, translocation was greater in unifoliate leaves. Reduced translocation by trifoliate foliage contributes to imazapic tolerance of older Florida beggarweed seedlings.
Preharvest Aflatoxin Contamination in Drought-Tolerant and Drought-Intolerant Peanut Genotypes1
Authors: Holbrook C. C. , Kvien C. K. , Rucker K. S. , Wilson D. M. , Hook J. E. , Matheron M. E.
Published: April 2010

Peanuts become contaminated with aflatoxins when subjected to prolonged periods of heat and drought stress. The effect of drought tolerance on aflatoxin contamination is not known. The objectives of this research were to evaluate preharvest aflatoxin contamination in peanut genotypes known to have drought tolerance and to determine the correlation of drought tolerance characteristics with aflatoxin contamination. Twenty genotypes with different levels of drought tolerance were grown in Yuma, AZ (a desert environment) and under rain-protected shelters in Tifton, GA. Two drought-tolerant genotypes (PI 145681 and Tifton 8) and an intolerant genotype (PI 196754) were selected for further examination in a second experiment with two planting dates in 1997 at Tifton. Drought and heat stress conditions were imposed for the 40 d preceding harvest. The drought-intolerant genotype had greater preharvest aflatoxin contamination than Florunner (the check cultivar) in the tests conducted in 1997. Both drought-tolerant genotypes had less preharvest aflatoxin contamination than Florunner in these tests. Significant positive correlations were observed between aflatoxin contamination and leaf temperature and between aflatoxin contamination and visual stress ratings. Leaf temperature and visual stress ratings are less variable and less expensive to measure than aflatoxin contamination. Leaf temperature and visual stress ratings maybe useful in indirectly selecting for reduced aflatoxin contamination in breeding populations.
Alterations of Leaf Epicuticular Wax of Peanut (Arachis hypogaea) by Applications of Herbicides and Adjuvants1
Authors: Baysinger J. A. , Melouk H. A. , Murray D. S.
Published: April 2010

Leaf surface morphology of untreated peanut leaves and peanut leaves treated with herbicides and adjuvants were examined using scanning electron microscopy. Electron micrographs revealed that the adaxial surface of untreated peanut leaves was covered with crystalline wax platelets above an amorphous layer of wax. Electron micrographs revealed that peanut leaves treated with acifluorfen plus nonionic surfactant, bentazon and lactofen with crop oil concentrate, and 2,4-DB, altered the leaf surface morphology when compared to nontreated peanut leaves. Alterations in the leaf epicuticular wax structures appeared amorphous-like rather than normal plate-like structures. Nonionic surfactant and crop oil concentrate applied alone to peanut leaves altered the epicuticular wax structures similarly to that of herbicides plus adjuvants.
Impact of Plant Spacing and Population on Yield for Single-Row Nonirrigated Peanuts (Arachis hypogaea L.)
Authors: Sternitzke D. A. , Lamb M. C. , Davidson J. I. , Barron R. T. , Bennet C. T.
Published: April 2010

Poor peanut emergence often results in lower yield and loss of revenue. Farmers attempting to recapture lost income sometimes lose even more by replanting because replant costs may exceed the benefits of added yield. The purpose of this study was to develop an empirical equation to predict peanut yield based on total emergence 21 d after planting and an estimate of yield for a full stand of peanuts. Field experiments were conducted in Terrell Co., Georgia during 1997 and 1998 for nonirrigated peanut (cv. Georgia Green) grown in an Americus sand (thermic Rhodic Paleudults). To mimic poor emergence and concomitant random plant spacing, rows within plots were thinned at random locations to attain populations of 4.4, 3.3, 2.6, 2.1, and 1.6 plants/m-row. Control plots were not thinned and total emergence was approximately 12.7 plants/m-row. As total emergence and population decreased, yield also decreased whereas pod mass per plant increased. This increase was likely attributed to a reduction in competition from adjacent peanut plants for water, nutrients, and light. Higher population treatments had smaller pod mass/plant and greater overall yield than lower population treatments with higher pod mass/plant. Random plant-to-plant spacing associated with poor emergence was used to predict pod mass/plant as a function of average plant spacing. Results from this research established models defining the relationship of the rate of change of pod mass per plant with average plant spacing and provided a new method of predicting yield in the event of poor emergence.
Effects of Storage Environment on Farmers Stock Peanut Grade Factors in an Aerated Warehouse in West Texas
Authors: Blankenship P. D. , Grice G. M. , Butts C. L. , Lamb M. C. , Sanders T. H. , Horn B. W. , Dorner J. W.
Published: April 2010

Temperature and relative humidity (RH) in an aerated warehouse in west Texas were monitored during storage of 1994 and 1995 crop farmer stock (FS) peanuts. Temperature and RH were measured at various positions throughout a vertical cross section of the peanut mass in the overspace and outside the warehouse. Data were collected at 1-hr intervals throughout storage. Peanut mass temperatures averaged 9.6 C during storage for the 1994 crop and 10.3 C for the 1995 crop. Relative humidity for the 1994 crop storage averaged 68.3 and 57.9% for the 1995 crop storage. Farmer stock grades were collected at warehouse loading and unloading for 10- to 12-t lots of peanuts stored in the warehouse (Wpnuts) and for samples (Spnuts) positioned at temperature and RH sensor locations. Wpnuts, in approaching equilibrium moisture with ambient RH, lost 2% moisture content both storage years. Spnuts lost 1.4% moisture content during storage of both crops. Percentage sound mature kernels (SMK) from Wpnuts decreased by 3.3% during 1994 crop storage and 6.6% during 1995 crop storage. Percentage SMK from Spnuts decreased 2.2 and 6.2% for the two storage years. Percentage sound splits (SS) for the Wpnuts increased 2.2% during 1994 crop storage and 4.2% during the 1995 crop storage. Percentage SS for Spnuts increased 2.4 and 6.1%, respectively. Changes in other grade factors were not consistent comparing percentage values for Wpnuts and Spnuts. Data indicate that maintaining grade and quality during FS peanut storage in west Texas will require knowledge of moisture content of peanuts placed into the warehouse and environmental monitoring in order to determine storage length. For 3- to 5-mo storage, it is recommended that FS peanuts have a moisture content close to 10% when placed into storage for peanuts to be above 7% when unloaded from the warehouse.
Feasibility of Purchasing Screened Farmer Stock Peanuts: The Sheller's Perspective
Authors: Lamb M. C. , Blankenship P. D.
Published: April 2010

Mechanical screening to separate foreign material, loose shelled kernels (LSK), and smaller, lower value pods (thrus) from larger, higher value pods (overs) increased the value of peanut lots compared to unscreened lots. The average value of overs was $29.15 per Mg higher than unscreened peanuts. Marketing overs translates into higher purchase cost to shellers. The percentage of LSK in unscreened peanuts was a key factor in whether shellers would prefer to purchase screened lots because, as LSK of unscreened lots increases, the value per Mg of farmer stock (FS) peanuts decrease. The value of unscreened lots with 1% LSK was $12.33 per Mg less (not significant) than the resulting value of lots after screening, while the value of unscreened lots with 10% LSK was $57.57 per Mg less (P = 0.01) than the resulting value of lots after screening. LSK in screened lots were generally reduced to less than 1% limiting the availability of LSK for shellers to recover and use in edible channels. However, removal of high risk components (LSK and small kernels) should reduce aflatoxin levels in overs lots compared to unscreened lots. Significant increases in jumbo and medium outturn and decreases in No. 1 outturn were associated with shelling screened lots. Gross shelled stock value increased $32.37 per Mg for screened lots with no LSK recovery and $10.82 per Mg for unscreened lots with total LSK recovery. The differences in dollar returns from purchasing and shelling screened lots were compared to unscreened lots for different levels of LSK in unscreened lots and varying LSK recovery levels into edible channels.
Winter Fallow Management of Volunteer Peanut (Arachis hypogaea L.) and Cutleaf Eveningprimrose (Oenothera laciniata Hill)
Authors: Johnson W. C. , Baldwin J. A. , Mullinix B. G.
Published: April 2010

Volunteer peanut and cutleaf eveningprimrose are part of the epidemiology of spotted wilt disease of peanut and other susceptible crops in the Southeastern U.S. Coastal Plain. Studies were conducted on the timing and frequency of fallow harrowing, integrated with applications of glyphosate or tribenuron-methyl, for control of volunteer peanut and cutleaf eveningprimrose. Spring harrowing was generally more effective in controlling volunteer peanut than fall or winter harrowing. Conversely, cutleaf eveningprimrose was controlled by sequential harrowing in the fall, winter, and spring, with single harrowing less effective. In general, spring applications of glyphosate or tribenuron-methyl were equally effective in controlling volunteer peanut and cutleaf eveningprimrose in absence of tillage.
Comparison of Virginia and Runner Market-Type Peanut (Arachis hypogaea) Grown in the Virginia-Carolina Production Region
Authors: Jordan D. L. , Swann C. W. , Spears J. F. , Brandenburg R. L. , Bailey J. E. , Tucker M. R.
Published: April 2010

Research was conducted in North Carolina and Virginia from 1997 through 1999 to compare runner and virginia market-type peanuts as influenced by cultivar selection, fertility practices, and pest management strategies. The runner market-type cultivar Georgia Green yielded and provided gross market value equivalent to the virginia market-type cultivar NC-V11 under a wide range of edaphic and environmental conditions. Calcium (as gypsum) applied at initial pegging increased the percentage of extra large kernels, the percentage of total sound mature kernels, and market value (c/kg) of the virginia market-type cultivar Gregory. The runner market-type cultivars Georgia Green and GK-7 were less responsive to calcium. Response of both market types was dependant upon environmental conditions. Pest management strategy affected pod yield, gross value, and economic return of peanut similarly for both virginia and runner market types. Results from these studies suggest that runner market-type peanut can provide pod yield, gross value, and economic returns similar to commonly grown virginia market-type peanut when grown in the Virginia-Carolina region. However, the peanut industry in the Virginia-Carolina region is designed for virginia market-type peanut used for the in-shell market, and popularity of growing runner market-type peanut in this region will most likely depend upon market pressures rather than agronomic potential.
Expression of Nematode Resistance in Plant Introductions of Arachis hypogaea
Authors: Timper P. , Holbrook C. C. , Xue H. Q.
Published: April 2010

The peanut root-knot nematode (Meloidogyne arenaria, race 1) is a world-wide pest of peanut (Arachis hypogaea L.). Several moderately resistant genotypes have been identified in the cultivated peanut species. Our objective was to determine the expression of resistance for six of these genotypes. We examined four potential expressions of resistance—(a) fewer second-stage juveniles (J2) penetrate the roots, (b) fewer J2 establish functional feeding sites, (c) slower maturation, and (d) reduced fecundity (eggs per female). Seedlings of the susceptible cultivar Florunner and the resistant genotypes were inoculated with J2 of M. arenaria, and transplanted 3 d later to synchronize nematode development. Penetration was assessed at 3 and 10 d; development at 10 (or 12), 17, 22, and 27 d; and fecundity at 60 d after inoculation. The experiments were conducted in a greenhouse or growth chamber. The number of J2 within the roots was similar in resistant and susceptible peanut after 3 d; however, numbers were lower in two of the resistant genotypes than in Florunner after 10 d. A greater percentage of J2 failed to develop in all of the resistant genotypes (72 to 79%) than in Florunner (50%) after 17 d. Of the J2 that did begin to develop, the rate of maturation and fecundity was similar in resistant and susceptible genotypes. A lack of development indicates that the J2 failed to establish a feeding site. Therefore, the primary expression of resistance in the six peanut genotypes appears to be a reduction in the percentage of J2 that establish a functional feeding site. The decline in J2 after infection may be related to the failure to establish a feeding site.