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Cotton (Gossypium hirsutum L.) is a major rotational crop associated with peanut (Arachis hypogaea L.) cropping systems in Southwest Georgia. Since peanut is typically planted in twin-rows for greater yield and grade, use of the same twin-row planter for cotton would be cost effective. It is not clear what effect row pattern would have on cotton lint yield using drip irrigation. The objectives were to compare cotton yield when planted in different row patterns, with two plant densities, at multiple locations, and irrigated with drip and sprinkler irrigation systems. Cotton was planted in single- and twin-row patterns at recommended (1X) and half-recommended (0.5X) seeding rates (93,000 and 54,600 seeds/ha, respectively). Irrigation systems were subsurface drip irrigation (SSDI), shallow subsurface drip irrigation (S3DI), and overhead sprinkler. Row pattern (single- or twin-row), seeding rate, or irrigation system had no effect on lint yield. There were fiber quality differences, probably due to cultivar, but there was no consistency to draw any conclusions. For consistent year-to-year yield and economics, it is recommended to plant cotton near 1X seeding rates using single- or twin-rows with either drip or sprinkler irrigation systems. Seeding rates reduced to half or lower than the recommended rate may increase risk of lower yields and revenue that may not be covered by money saved using less seed.

Wild diploid Arachis species are potential sources of resistance to early (ELS) and late (LLS) leaf spot diseases caused by Passalora arachidicola (syn. Cercospora arachidicola Hori), and Nothopassalora personata (syn. Cercosporidium personatum (Berk. & Curt.) Deighton), respectively. Within section Arachis, limited information is available on the extent of genetic variation for resistance to these fungal pathogens. A collection of 78 accessions representing 15 wild species of Arachis section Arachis from the U.S peanut germplasm collection was evaluated for resistance to leaf spots. Screening was conducted under field (natural inoculum) conditions in Dawson, Georgia, during 2017 and 2018. Accessions differed significantly (P < 0.01) for all three disease variables evaluated, which included final defoliation rating, ELS lesion counts, and LLS lesion counts. Relatively high levels of resistance were identified for both diseases, with LLS being the predominant pathogen during the two years of evaluation. This research documents new sources of resistance to leaf spot diseases selected from an environment with high inoculum pressure. The presence of ELS and LLS enabled the selection of resistant germplasm for further introgression and pre-breeding.

Early leaf spot (ELS) and late leaf spot (LLS) are major fungal diseases of peanut that can severely reduce yield and quality. Development of acceptable genetic resistance has been difficult due to a strong environmental component and many major and minor QTLs. Resistance genes (R-genes) are an important component of plant immune system and have been identified in peanut. Association of specific R-genes to leaf spot resistance will provide molecular targets for marker-assisted breeding strategies. In this study, advanced breeding lines from different pedigrees were evaluated for leaf spot resistance and 76 candidate R-genes expression study was applied to susceptible and resistant lines. Thirty-six R-genes were differentially expressed and significantly correlated with resistant lines, of which a majority are receptor like kinases (RLKs) and receptor like proteins (RLPs) that sense the presence of pathogen at the cell surface and initiate protection response. The largest group was receptor-like cytoplasmic kinases (RLCKs) VII that are involved in pattern-triggered kinase signaling resulting in the production reactive oxygen species (ROS). Four R-genes were homologous to TMV resistant protein N which has shown to confer resistance against tobacco mosaic virus (TMV). When mapped to peanut genomes, 36 R-genes were represented in most chromosomes except for A09 and B09. Low levels of gene-expression in resistant lines suggest expression is tightly controlled to balance the cost of R-gene expression to plant productively. Identification and association of R-genes involved in leaf spot resistance will facilitate genetic selection of leaf spot resistant lines with good agronomic traits.

Although the Southeast U.S. receives an average annual precipitation of 1300 mm, crop yields are often limited by erratic seasonal rainfall distributions. Studies were conducted from 2001 through 2017 at the USDA/ARS Multi-crop Irrigation Research Farm in Shellman, GA (84°36′ W, 30°44′ N) on a Greenville fine sandy loam (fine, kaolinitic, thermic Rhodic Kandiudults). The objective of this long-term study is to evaluate the effects of irrigation and crop rotation sequencing consisting of peanut, corn, and cotton on yield and net economic returns to both variable and total costs. Analysis included the entire study period and was also separated for years with below and above average rainfall. When averaged across all years, irrigation increased peanut, corn, and cotton yield and net returns compared with non-irrigation. Six different rotation sequences were addressed inclusive of continuous peanut, one year out of peanut with corn or cotton, and two years out of peanut with combinations of corn and cotton. In both irrigated and non-irrigated peanuts, the least and greatest yields were from continuous peanut and the two year out rotations, respectively. No peanut yield difference resulted with corn or cotton rotation partners for the rotation sequence. Length of rotation between peanut years did influence peanut yield and net returns. Profitability and optimal rotation sequence within any cropping system depended on irrigation, yield, crop price, and production costs for peanut, corn, and cotton.

Although seed and pod traits are important for peanut breeding, little is known about the inheritance of these traits. A recombinant inbred line (RIL) population of 156 lines from a cross of Tifrunner x NC 3033 was genotyped with the Axiom_Arachis1 SNP array and SSRs to generate a genetic map composed of 1524 markers in 29 linkage groups (LG). The genetic positions of markers were compared with their physical positions on the peanut genome to confirm the validity of the linkage map and explore the distribution of recombination and potential chromosomal rearrangements. This linkage map was then used to identify Quantitative Trait Loci (QTL) for seed and pod traits that were phenotyped over three consecutive years for the purpose of developing trait-associated markers for breeding. Forty-nine QTL were identified in 14 LG for seed size index, kernel percentage, seed weight, pod weight, single-kernel, double-kernel, pod area and pod density. Twenty QTL demonstrated phenotypic variance explained (PVE) greater than 10% and eight more than 20%. Of note, seven of the eight major QTL for pod area, pod weight and seed weight (PVE >20% variance) were attributed to NC 3033 and located in a single linkage group, LG B06_1. In contrast, the most consistent QTL for kernel percentage were located on A07/B07 and derived from Tifrunner.

Indeterminate growth of peanut (Arachis hypogaea L.) creates indecision for best digging date for maturity and economic return. The current standard to determine peanut maturity is the Hull Scrape method. This method uses human observations to place hull scraped peanuts on a color maturity profile board. Human observations may lack precision and repeatability from individual to individual. X-ray technology has the capability of viewing peanut kernels through the hull to possibly ascertain density and maturity. The objective was to determine if x-ray could be used as a quick, non-destructive, and repeatable method to determine peanut maturity of runner, spanish, and virginia market types. Fresh dug peanut pods had 25 percent greater peanut area and gray scale values compared with hull scraped pods (runner and virginia only) and showed no difference in x-ray value between immature and fully mature peanut. Dried peanut showed a linear response of x-ray value versus peanut maturity (hull color). Virginia market type had much higher x-ray values followed by runners, then spanish. The relationship between peanut maturity and x-ray value peaked at the Orange class for runners (Georgia-06G, Georgia-13M), and Spanish (AT9899) while virginia (Georgia-11J) tended to peak at the Brown class. This research demonstrated that x-ray technology may be used to measure peanut density and possible maturity but needs further examination past Orange and Brown maturity class. Final x-ray values determined by this proprietary x-ray equipment may not be transferable due to specific x-ray power, detector precision, background color/scatter, and other electronic nuances.

Napier grass (Pennisetum purpureum (L) Schum) is being developed as a bioenergy crop for production in the southeastern United States. Important criteria for selecting a feedstock are cost, consist...

Scheduling irrigation events in the humid Southeast can be challenging due to unreliable rainfall patterns. The objective of this study was to evaluate three water potential strategies for scheduling irrigation events in cotton (Gossypium hirsutum L.) using shallow subsurface drip irrigation (S3DI) with respect to lint yield and quality, irrigation water-use efficiency (IWUE), and value water-use efficiency (VWUE). Research was conducted in 2012 through 2016 in southwest Georgia, U.S. using an S3DI system. Water potential sensors were installed at 25- and 50-cm soil depth. Irrigation treatments and events occurred when the average water potential values were: -40 kPa (treatment I1), -70 kPa (treatment I2), -70/-40/-60 kPa (treatment I3) (emergence to 1st square/1st square to 1st cracked boll/1st cracked boll to defoliation) and a dryland control. All irrigated treatments had higher yield (1975 kg ha-1) than dryland (987 kg ha-1) except during 2013 (wet year). When 2013 data was deleted, there was no lint yield difference across years (p = 0.07) or across irrigation treatments (p = 0.06). Irrigation treatments I2 and I3 applied 170 mm less irrigation water compared to I1. There were differences in lint quality by irrigation treatment and year, but quality values were within acceptable ranges little or no price deductions. Dry year IWUE for treatments I2 and I3 averaged 3.1 kg lint mm-1 compared with I1 at 2.2 kg lint mm-1. For VWUE, both I2 and I3 had 44% greater value per unit of irrigation applied compared with I1. Either I2 or I3 can be used for scheduling irrigation events efficiently and economically.

Low oxygen or hermetic storage has been successfully used to store several commodities such as corn (Zea mays L.), cowpea (Vigna Savi), cocoa (Theobroma cocao), and coffee (Coffea L.), rice (Oryza sativa L.). However, previous research using hermetic storage for peanut or groundnut (Arachis hypogaea L.) has had mixed results. Research was conducted to determine the effect on aflatoxin contamination, seed germination, and oil chemistry of shelled peanut hermetically stored in the Purdue Improved Crop Storage (PICS) bags for up to 12 months. A 2 x 4 factorial study included 1) normal and high oleic peanut, 2) two initial moisture contents by four storage treatments. The four storage treatments were 1) burlap bags as the control, 2) PICS bags, 3) PICS bags with air extracted by vacuum, and 4) PICS bags with sachets of chlorine dioxide (ClO 2 ) dry fumigant added. There were three replications of each treatment combination. Peanut was stored in an area maintained at a temperature above 21C. The initial seed germination of the normal oleic and high oleic peanuts was 77 and 80%, respectively. Initial aflatoxin concentration in all peanut was less than 2 µg/kg . Bags were opened, sampled, and resealed at 60, 159, 249, and 301 d of storage. Approximately half of the 12 burlap bags suffered significant rodent damage, and all had significant infestation by Indian meal moth ( Plodia interpunctella ). Only 4 PICS bags had rodent damage with damage limited to the outer polypropylene bag. There were no live insects in the PICS bags. Seed germination decreased for all samples to an average of 6.3%. Peanut stored in the burlap bags had an average germination of 19.2% compared to 2.1% for peanut stored in PICS bags. The aflatoxin concentration in one of the burlap bags with normal oleic peanuts was 75 µg/kg, and one of the PICS bags with high oleic peanuts had an aflatoxin concentration of 12 µg/kg. The remaining samples had aflatoxin below the detectable limit of 2 µg/kg.

Peanut smut caused by Thecaphora frezii is a severe fungal disease currently endemic to Argentina and Brazil. The identification of smut resistant germplasm is crucial in view of the potential risk of a global spread. In a recent study, we reported new sources of smut resistance and demonstrated its introgression into elite peanut cultivars. Here, we revisited one of these sources (line I0322) to verify its presence in the U.S. peanut germplasm collection and to identify single nucleotide polymorphisms (SNPs) potentially associated with resistance. Five accessions of Arachis hypogaea subsp. fastigiata from the U.S. peanut collection, along with the resistant source and derived inbred lines were genotyped with a 48K SNP peanut array. A recently developed SNP genotyping platform called RNase H2 enzyme-based amplification (rhAmp) was further applied to validate selected SNPs in a larger number of individuals per accession. More than 14,000 SNPs and nine rhAmp assays confirmed the presence of a germplasm in the U.S. peanut collection that is 98.6% identical (P < 0.01, bootstrap t-test) to the resistant line I0322. We report this germplasm with accompanying genetic information, genotyping data, and diagnostic SNP markers. Fil: Massa, Alicia N.. National Peanut Research Laboratory; Estados Unidos Fil: Bressano, Marina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Fitopatología y Fisiología Vegetal; Argentina Fil: Soave, Juan H.. Criadero El Carmen; Argentina Fil: Buteler, Mario I.. Criadero El Carmen; Argentina Fil: Seijo, José Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; Argentina Fil: Sobolev, Victor S.. National Peanut Research Laboratory; Estados Unidos Fil: Orner, Valerie A.. National Peanut Research Laboratory; Estados Unidos Fil: Oddino, Claudio Marcelo. Criadero El Carmen; Argentina Fil: Soave, Sara J.. Criadero El Carmen; Argentina Fil: Faustinelli, Paola Carmen. National Peanut Research Laboratory; Estados Unidos Fil: de Blas, Francisco Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Lamb, Marshall C.. National Peanut Research Laboratory; Estados Unidos Fil: Arias, Renee S.. National Peanut Research Laboratory; Estados Unidos

Draft genomes of 16 isolates of Aspergillus flavus Link and Aspergillus parasiticus Speare, identified as the predominant genotypes colonizing peanuts in four farming regions in Ethiopia, are reported. These data will allow mining for sequences that could be targeted by RNA interference to prevent aflatoxin accumulation in peanut seeds.

Peanut (Arachis hypogaea L.) is an important food and oilseed crop worldwide. Yield and quality can be significantly reduced by foliar fungal diseases, such as early and late leaf spot diseases. Acceptable levels of leaf spot resistance in cultivated peanut have been elusive due to environmental interactions and the proper combination of QTLs in any particular peanut genotype. Resistance gene analogs, as potential resistance (R)-genes, have unique roles in the recognition and activation of disease resistance responses. Novel R-genes can be identified by searches for conserved domains such as nucleotide binding site, leucine rich repeat, receptor like kinase, and receptor like protein from expressed genes or through genomic sequences. Expressed R-genes represent necessary plant signals in a disease response. The goals of this research are to identify expressed R-genes from cultivated peanuts that are naturally infected by early and late spot pathogens, compare these to the closest diploid progenitors, and evaluate specific gene expression in cultivated peanuts. Putative peanut R-genes (381) were available from a public database (NCBI). Primers were designed and PCR products were sequenced. A total of 214 sequences were produced which matched to proteins with the corresponding R-gene motifs. These R-genes were mapped to the genome sequences of Arachis duranensis and Arachis ipaensis, which are the closest diploid progenitors for tetraploid cultivated peanut, A. hypogaea. Identification and association of specific gene-expression will elucidate potential disease resistance mechanism in peanut and may facilitate the selection of breeding lines with high levels of leaf spot resistance.

A peanut vacuum developed by redesigning an existing grain vacuum (vac) specifically to handle farmers' stock peanuts was tested. The peanut vac consists of a PTO-driven positive displacement blower, two cyclone separators, and a hydraulically-powered airlock valve. The blower pulls air and farmers' stock peanuts through a length of suction hose into the first cyclone separator where the peanuts are separated from the airstream. The air then travels to a second cyclone separator where the suspended dirt and other fine particles are separated from the airstream. The cleaned air proceeds through the blower and is blown through a discharge chute beneath the outlet of an airlock valve mounted on the bottom of the first cyclone. Farmers' stock peanuts from the first cyclone fall from the outlet of the airlock valve into the airstream in the discharge chute and are conveyed up into a waiting trailer. The peanut vac is powered by a 1000-rpm PTO shaft of a tractor supplying a minimum of 75 kW. Initial feasibility tests were conducted while unloading 1/10-scale farmers' stock warehouses to determine the optimum operating parameters to minimize mechanical damage. The optimized peanut vac was taken to two locations in South Georgia and used to extract peanuts from farmers' stock warehouses in addition to the conventional equipment used for warehouse bailout. The weight of peanuts on each truck, time to fill each truck, and the farmers' stock grade factors for the peanuts in each truck was recorded and compared by conveyance method. At the first location, the conventional equipment consisted of a skid-steer loader with an oversized bucket driven into the pile of peanuts. The peanuts were emptied into a surge bin feeding a portable conveyor belt that conveyed the peanuts into a waiting truck. At the second location, a large articulated bucket loader was used in lieu of the skid-steer loader. Peanuts loaded using the conventional method averaged 5.2% foreign material (FM) and 6.7% loose shelled kernels (LSK). Peanuts loaded using the peanut vac averaged 2.7 and 4.9% FM and LSK, respectively. Trucks were loaded at a rate of 187 MT/h using conventional equipment compared to 61MT/h using the peanut vac.

Interest and focus on development of renewable biofuels has been increasing over the past decade leading to the introduction of a wide cadre of renewable feedstocks. As a result, numerous perennial warm-season grasses have been introduced and management practices evaluated to determine their suitability as biofuel feedstocks. “Merkeron” napier grass (Pennisetum purpureum) plots were established in 2010 and harvested during crop years 2011 through 2015 adjacent to an on-going peanut (Arachis hypogaea L.), corn (Zea mays L.), and cotton (Gossypium hirsutum L.) cropping systems study conducted at the USDA/ARS Multi-crop Irrigation Research Farm in Shellman, GA (84 36 W, 30 44 N) on a Greenville fine sandy loam (fine, kaolinitic, thermic Rhodic Kandiudults). Napier grass was produced in both non-irrigated and two irrigated levels with different levels of nitrogen and potassium fertilizers. Peanut, corn, and cotton were produced in non-irrigated and full irrigation regimes. Breakeven prices for napier grass ranged from $65 to $84 Mg−1 at variable and total costs. The breakeven napier grass price was estimated such that the net returns were equal between napier grass and peanut, cotton, corn cropping systems. At variable production cost, comparative breakeven napier grass prices for non-irrigated, 50% irrigated, and full irrigated regimes were $77, $117, and $112 Mg−1, respectively. Napier grass did not compete economically against traditional irrigated cropping systems. Depending on traditional crop prices and bioenergy feed stock prices, napier grass could offer economic opportunities in non-irrigated production environments, riparian buffer zone edges, or non-cropped marginal production areas.

The concentration of mercury, cadmium, lead, and arsenic along with glyphosate and an extensive array of pesticides in the U.S. peanut crop was assessed for crop years 2013-2015. Samples were randomly selected from various buying points during the grading process. Samples were selected from the three major growing regions in order to attain a representative sample of U.S. peanut production. Samples were sent to an independent laboratory for testing. Appropriate statistical techniques were used to account for censored data due to test results below detection limits. Descriptive statistics and confidence intervals for the population mean concentration are presented where possible. For heavily censored data, the probability of a random sample from the population testing below the detection limit is estimated. Overall, concentrations were found to be low relative to health standards and consistent across crop years.

Studies were conducted in small chambers and commercial storage facilities to evaluate the effect of storing shelled peanuts at 3, 13, and 21 C (38, 55, 70 F) for one year. Shelled medium runner peanuts from the 2014 crop were placed in the three different environments in Feb 2015, sampled at 60-d intervals until Feb 2016 (364 days). Difficulty maintaining the desired relative humidity of 65% in the 3 C unit, led to unacceptable mold growth and severely degraded seed germination. Peanuts stored at 21 C developed an infestation of Indian meal moth after 238 d in storage rendering the samples unsuitable for sensory analysis from that point forward. The infestation most likely occurred due to hatches of eggs that were present in the original samples. Sensory analyses showed very little change in the intensity of the Roasted Peanut flavor characteristic in either storage environments. There were no unacceptable increases in free fatty acids or peroxide values during the 1-yr storage period for peanuts stored at 13 C. The percent free fatty acids in peanuts stored at 13 C remained well below 1% throughout the 1-yr study. Commercial studies were conducted from Feb 2015 through Mar 2016. Six 60-d runs were conducted where three totes of medium runner peanuts from the same manufacturing lot were placed in commercial cold storage facilities maintained at 3 and 13 C. There were no differences in the initial moisture content of peanuts when placed in the two storage environments. However, after 30 and 60-d storage, the peanuts stored at 13 C tended to be an average of 0.3% dryer than those stored at 3 C. The peanuts had the highest increase in moisture between June and August 2015, with the moisture content after 30 and 60 d storage at 3 C averaged 8.1 and 7.7%, respectively. The peanuts stored in the 13 C environment averaged 7.6 and 7.3% moisture content after 30 and 60 d in storage, respectively. This study has shown that shelled peanuts can be stored for up to one year with no detrimental effects at temperatures up to 13 C and relative humidity ranging from 55 to 70%. Based on this research, the recommended temperature for storing shelled peanuts can be increased to 13 C, while maintaining the relative humidity between 55 and 70%.

Normal oleic peanuts are often found within commercial lots of high oleic peanuts when sampling among individual kernels. Kernels not meeting high oleic threshold could be true contamination with normal oleic peanuts introduced via poor handling, or kernels not meeting threshold could be immature and not fully expressing the trait. Beyond unintentional mixing, factors contributing to variation in oleic acid concentration in peanut kernels include market type, environment, maturity and/or kernel size; however, the relative influence of these factors, and their interactions, is not quantitatively well understood on the single kernel level. To better understand these factors while simultaneously excluding variation from unintentional mixing, seed from a high oleic spanish cultivar and seed from a high oleic runner cultivar were carefully purified via NIR technology. The purified seed were planted in environmentally controlled test plots to analyze the progeny for oleic acid chemistry. Post flowering, plot sections were either chilled (3.8 -5.0 C below ambient), maintained at ambient or heated (3.8-5.0 C above ambient) in the pod zone to characterize soil temperature effects on oleic acid chemistry development. Fully randomized (4 reps) plots included the purified high oleic spanish and runner cultivars, three soil temperatures, seed maturity (profile board), commercial kernel size classifications, and a late season flower termination protocol. At harvest, the oleic acid concentration of approximately 24,000 individual kernels were measured via NIR technology. Market type, temperature, maturity and size had a significant effect on high oleic chemistry among kernels. Late season flower termination significantly, and positively, influenced high oleic chemistry of runner peanuts, minimized the number of immature kernels not meeting high oleic threshold and resulted in elevated and more consistent distributions in this key chemistry; distributions that were more similar to those of the more botanically determinate, but lower yielding, spanish market type. Data from this study improves our understanding of expected natural variation in high oleic chemistry and suggests late season flower termination of runner peanuts is a viable strategy to maximize high oleic chemistry on the single kernel level.

Aflatoxin contamination is a major constraint in food production worldwide. In peanut (Arachis hypogaea L.), these toxic and carcinogenic aflatoxins are mainly produced by Aspergillus flavus Link and A. parasiticus Speare. The use of RNA interference (RNAi) is a promising method to reduce or prevent the accumulation of aflatoxin in peanut seed. In this study, we performed high-throughput sequencing of small RNA populations in a control line and in two transformed peanut lines that expressed an inverted repeat targeting five genes involved in the aflatoxin-biosynthesis pathway and that showed up to 100% less aflatoxin B1 than the controls. The objective was to determine the putative involvement of the small RNA populations in aflatoxin reduction. In total, 41 known microRNA (miRNA) families and many novel miRNAs were identified. Among those, 89 known and 10 novel miRNAs were differentially expressed in the transformed lines. We furthermore found two small interfering RNAs derived from the inverted repeat, and 39 sRNAs that mapped without mismatches to the genome of A. flavus and were present only in the transformed lines. This information will increase our understanding of the effectiveness of RNAi and enable the possible improvement of the RNAi technology for the control of aflatoxins.

Peanut (Arachis hypogaea) is a botanically indeterminate plant where flowering, fruit initiation, and pod maturity occurs over an extended time period during the growing season. As a result, the maturity and size of individual peanut pods vary considerably at harvest. Immature kernels that meet commercial edible size specifications negatively affect quality during processing due to their increased propensity for off flavors, higher moisture and water activity, and variable roasting properties. As peanuts progress toward maturation, late season flowers set within 40 days till harvest will not have sufficient time to develop into mature, marketable pods prior to harvest. Research was conducted to determine the effect of late season flower termination on peanut yield, grade, and seed germination. Diflufenzopyr-Na (Diflufenzopyr) (BASF Biosciences), a synthetic auxin transport inhibitor, and the herbicide glyphosate were applied at three sub-lethal rates along with a “hand flower removal” and a non-treated control in both irrigated and non-irrigated plots. No differences in non-irrigated pod yield across all treatments were detected. Glyphosate at 56 and 112 g/ha increased non-irrigated sound mature kernels plus sound splits (SMK+SS) and decreased other kernels (OK). Non-irrigated seed germination was negatively affected by glyphosate. Diflufenzopyr at 17 and 25 g/ha increased irrigated peanut yield. Glyphosate at 112 and 168 g/ha increased irrigated SMK+SS and decreased OK and germination.

Common soil fungi, Aspergillus flavus and Aspergillus parasiticus, are opportunistic pathogens that invade preharvest peanut seeds. These fungi often produce carcinogenic aflatoxins that pose a threat to human and animal health through food chains and cause significant economic losses worldwide. Detection of aflatoxins and further processing of crops are mandated to ensure that contaminated agricultural products do not enter food channels. Under favorable conditions, the fungus-challenged peanut seeds produce phytoalexins, structurally related stilbenoids, capable of retarding fungal development. The purpose of the present study was to evaluate the potential influence of peanut phytoalexins on fungal development and aflatoxin formation in the course of peanut-fungus interaction. The present research revealed that during such interaction, aflatoxin formation was completely suppressed in A. flavus and A. parasiticus strains tested, when low concentrations of spores were introduced to wounded preincubated peanuts. In most of the experiments, when fungal spore concentrations were 2 orders of magnitude higher, the spores germinated and produced aflatoxins. Of all experimental seeds that showed fungal growth, 57.7% were aflatoxin-free after 72 h of incubation. The research provided new knowledge on the aflatoxin/phytoalexin formation in the course of peanut-fungus interaction.

Author(s): Sorensen, Ronald B.; Nuti, Russell C.; Lamb, Marshall C. | Abstract: Surface drip irrigation of field crops has been gaining interest in the farming community. However, rodent damage is one of the major drawbacks for SD acceptance. This research documents the cost of repairing drip tubing and effective­ness of several rodent control methods. Four sites were used to identify cost of repairing tubing. Treatments included untreated drip tubing, tubing that was lightly buried, sprayed with an insecticide or animal repellent, and edible rodenticide placed next to the tubing. Once a leak was found, it took an average of 4 minutes to repair the hole. Each repair had an average cost of $0.67 for labor and repair materials. This does not include time or transportation cost to find the leak. Rodent damage was the same in the untreated versus any chemical management technique. At Site 4, the animal repellent, Ropel® did have less rodent damage (2,392 holes/ha) compared with the untreated (6,049 holes/ha); however, the damage was extensive enough that it was more economical to replace than to repair the tubing. The drip tubing that was slightly buried had the best rodent control (5 holes/ ha) compared with all other treatments (1,771 holes/ha). One disadvantage of burying the drip tubing is removal. Strip tillage along with burying the drip tubing showed excellent resistance to rodent damage and appears to be a cost effective management tool for surface drip irrigation

Cultivated peanut (Arachis hypogaea L.) is a major oilseed crop providing edible oil and protein. Oil quality is determined by fatty acid composition including the ratio of oleic acid (C18:1) and linoleic acid (C18:2). A genome-wide association study with 13,382 single nucleotide polymorphisms (SNPs) was conducted to investigate the genetics basis of oil, protein, eight fatty acid concentrations, and O/L ratio (ratio of oleic and linoleic acid) using a diverse panel of 120 genotypes mainly selected from the U.S. peanut mini core collection grown in two years. A total of 178 significant quantitative trait loci (QTLs) associated with those seed composition traits were identified with phenotypic variation explained (PVE) from 18.35% to 27.56%. RNA-Seq analysis identified 282 DEGs (differentially expressed genes) within the 1 Mb of the significant QTLs for seed composition traits. Among those 282 genes, sixteen candidate genes for seed fatty acid metabolism and protein synthesis were screened according to the gene functions.

With global increases in the production of cellulosic biomass for fuel, or “biofuel,” concerns over potential negative effects of using land for biofuel production have promoted attention to concepts of agricultural landscape design that sustainably balance tradeoffs between food, fuel, fiber, and conservation. The Energy Independence Security Act (EISA) of 2007 mandates an increase in advanced biofuels to 21 billion gallons in 2022. The southeastern region of the USA has been identified as a contributor to meeting half of this goal. We used a GIS-based approach to estimate the production and N-removal potential of three perennial biofeedstocks planted as conservation buffers (field borders associated with riparian buffers, and grassed waterways) on the Coastal Plain of Georgia, USA. Land cover, hydrology, elevation, and soils data were used to identify locations within agricultural landscapes that are most susceptible to runoff, erosion, and nutrient loss. We estimated potential annual biomass production from these areas to be: 2.5–3.5 Tg for giant miscanthus (Miscanthus × giganteus), 2–8.6 Tg for “Merkeron” napier grass (Pennisetum purpureum), and 1.9–7.5 Tg for “Alamo” switchgrass (Panicum virgatum). When production strategies were taken into consideration, we estimated total biomass yield of perennial grasses for the Georgia Coastal Plain at 2.2–9.4 Tg year−1. Using published rates of N removal and ethanol conversion, we calculated the amount of potential N removal by these systems as 8100–51,000 Mg year−1 and ethanol fuel production as 778–3296 Ml year−1 (206 to 871 million gal. US).

Mesocarp hull color is the current standard to estimate digging date and peanut (Arachis hypogaea, L.) maturity with acceptable yield and grade. Subjectivity of pod color and pod placement on a color chart may give a false indication of when to dig peanuts. The objective was to determine if peg strength could be used to predict pod maturity, digging date, and resultant peanut yield. Peanut peg strength was collected for two years (2011 and 2012) on three peanut cultivars (Georgia-06G, Georgia-09B, and Tifguard), at multiple plant dates (2012 only) and multiple harvest dates to determine the relationship between peg strength versus pod maturity, peanut loss, and peanut yield. Peg strength was determined using an electronic force gage that would measure peak force. Average peg strength was different for all three cultivars with Georgia-06G having the greatest average peg strength followed by Georgia-09B, and Tifguard. In general, peanut yields were greater at early plant and harvest dates and decreased with time. Conversely, peanut pod loss was lower with early plant and harvest dates but increased with later harvest dates. There was a strong positive linear relationship between peg strength and peanut yield for each cultivar. However, there was a relatively small difference with peg strength values between the maximum and minimum peanut yield. There was no relationship between peg strength and mesocarp color (pod maturity, R2 = 0.007). Small differences in peg strength and the non-relationship between peg strength and pod maturity implies: 1) a large sample size would be needed to predict peanut yield, 2) the large sample size would increase time and manpower to determine average peg strength values, and 3) peg strength was not a valid criteria to determine pod maturity or predict digging date. Overall, peg strength may be useful to describe cultivar characteristics but may not be sufficiently robust to predict pod maturity digging date, or peanut yield.

Aflatoxins are among the most powerful carcinogens in nature. The major aflatoxin-producing fungi are Aspergillus flavus and A. parasiticus. Numerous crops, including peanut, are susceptible to aflatoxin contamination by these fungi. There has been an increased use of RNA interference (RNAi) technology to control phytopathogenic fungi in recent years. In order to develop molecular tools targeting specific genes of these fungi for the control of aflatoxins, it is necessary to obtain their genome sequences. Although high-throughput sequencing is readily available, it is still impractical to sequence the genome of every isolate. Thus, in this work, the authors proposed a workflow that allowed prescreening of 238 Aspergillus section Flavi isolates from peanut seeds from Georgia, USA. The aflatoxin biosynthesis cluster (ABC) of the isolates was fingerprinted at 25 InDel (insertion/deletion) loci using capillary electrophoresis. All isolates were tested for aflatoxins using ultra-high-performance liquid chromatography. The neighbor-joining, three-dimension (3D) principal coordinate, and Structure analyses revealed that the Aspergillus isolates sampled consisted of three main groups determined by their capability to produce aflatoxins. Group I comprised 10 non-aflatoxigenic A. flavus; Group II included A. parasiticus; and Group III included mostly aflatoxigenic A. flavus and the three non-aflatoxigenic A. caelatus. Whole genomes of 10 representative isolates from different groups were sequenced. Although InDels in Aspergillus have been used by other research groups, this is the first time that the cluster analysis resulting from fingerprinting was followed by whole-genome sequencing of representative isolates. In our study, cluster analysis of ABC sequences validated the results obtained with fingerprinting. This shows that InDels used here can predict similarities at the genome level. Our results also revealed a relationship between groups and their capability to produce aflatoxins. The database generated of Aspergillus spp. can be used to select target genes and assess the effectiveness of RNAi technology to reduce aflatoxin contamination in peanut.

Smut disease caused by the fungal pathogen Thecaphora frezii Carranza & Lindquist is threatening the peanut production in Argentina. Fungicides commonly used in the peanut crop have shown little or no effect controlling the disease, making it a priority to obtain peanut varieties resistant to smut. In this study, recombinant inbred lines (RILs) were developed from three crosses between three susceptible peanut elite cultivars (Arachis hypogaea L. subsp. hypogaea) and two resistant landraces (Arachis hypogaea L. subsp. fastigiata Waldron). Parents and RILs were evaluated under high inoculum pressure (12000 teliospores g -1 of soil) over three years. Disease resistance parameters showed a broad range of variation with incidence mean values ranging from 1.0 to 35.0% and disease severity index ranging from 0.01 to 0.30. Average heritability (h 2 ) estimates of 0.61 to 0.73 indicated that resistance in the RILs was heritable, with several lines (4 to 7 from each cross) showing a high degree of resistance and stability over three years. Evidence of genetic transfer between genetically distinguishable germplasm (introgression in a broad sense) was further supported by simple-sequence repeats (SSRs) and Insertion/Deletion (InDel) marker genotyping. This is the first report of smut genetic resistance identified in peanut landraces and its introgression into elite peanut cultivars. This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication. Fil: Bressano, Marina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Fitopatología y Fisiología Vegetal; Argentina. Universidad Nacional de Córdoba; Argentina Fil: Massarini, Alicia. Usda Ars National Peanut Research Laboratory; Estados Unidos. Universidad de Buenos Aires. Facultad de Ingeniería. Postgrado-Maestría en Política y Gestión de la Ciencia y Tecnología; Argentina Fil: Arias, Renee S.. Usda Ars National Peanut Research Laboratory; Estados Unidos Fil: de Blas, Francisco Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Oddino, Claudio Marcelo. Criadero El Carmen; Argentina Fil: Faustinelli, Paola Carmen. Usda Ars National Peanut Research Laboratory; Estados Unidos Fil: Soave, Sara Josefina. Criadero El Carmen; Argentina Fil: Soave, Juan H.. Criadero El Carmen; Argentina Fil: Pérez, Maria A.. Universidad Católica de Córdoba. Facultad de Ciencias Agropecuarias; Argentina Fil: Sobolev, Victor S.. Usda Ars National Peanut Research Laboratory; Estados Unidos Fil: Lamb, Marshall C.. Usda Ars National Peanut Research Laboratory; Estados Unidos Fil: Balzarini, Monica Graciela. Universidad Nacional de Córdoba; Argentina. Instituto Nacional de Tecnologia Agropecuaria. Centro de Investigaciones Agropecuarias. Unidad de Fitopatologia y Modelizacion Agricola. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Cordoba. Unidad de Fitopatologia y Modelizacion Agricola.; Argentina Fil: Buteler, Mario I.. Criadero El Carmen; Argentina Fil: Seijo, José Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; Argentina

Aspergillus flavus accumulates carcinogenic aflatoxins in peanuts, mainly in immature kernels during drought. Aspergillus flavus invasion induces accumulation of phytoalexins, mostly stilbenoids in peanut, as a plant defence mechanism. Because fungal laccases are often related to pathogenicity and can degrade stilbenoids, this study reports for the first time the expression of A. flavus laccases in the presence of kernels, hulls and low water potential in relation to the accumulation of phytoalexins in peanut kernels. Packed-cell volume (PCV) of A. flavus biomass was significantly higher (P ≤ 0·01) in the presence of mature kernels, dead kernels, and mature and immature peanut hulls than the control. The presence of kernels and hulls lowered the level of expression of three A. flavus laccases by 4–6-fold (P < 0·01), whereas 3% sucrose up-regulated them by 35–304-fold, and low water potential (−1·1 MPa) up-regulated them by 85–248-fold (P < 0·01). Phytoalexins that accumulated in peanut kernels in the presence of A. flavus and were quantified by HPLC-DAD-MS were primarily the stilbenoids: 3′-isopentadienyl-3,5,4′-trihydroxystilbene (IPD), chiricanine-A, arachidin-2, arachidin-3 and arahypin-1. Apparent degradation of phytoalexins was observed when using a priori induction of phytoalexins in seeds in combination with a priori induction of laccases in A. flavus. The up-regulation of laccase expression observed at −1·1 MPa and at high sucrose concentration could be contributing to peanut invasion in immature kernels under drought conditions.

Peanut meal (PM) is the high protein by-product remaining after commercial extraction of peanut oil. PM applications are limited because of typical high concentrations of aflatoxin. For the first time, pilot-scale extraction of protein and sequestration of aflatoxin from PM were evaluated. Aqueous PM dispersions were mixed with two commercial bentonite clays and Alcalase in a jacketed mixer, hydrolysed for 1 h, heated to inactivate protease, and solids and liquids were separated using a decanter. Liquid hydrolysates derived from this process had >90% reduction in aflatoxin when clay was present. ACE-inhibitory activities of these hydrolysates suggest a potential benefit for blood pressure regulation. The insoluble fractions from the dispersions were dried and used in a separate turkey poult feeding study. These results indicate that scale-up of this novel process is feasible and offers a means for adding value to this underutilized protein source.

Runner-type peanut kernel moisture content (MC) is measured periodically during curing and post harvest processing with electronic moisture meters for marketing and quality control. MC is predicted for 250 g samples of kernels with a mathematical function from measurements of various physical properties. To examine the accuracy of the function used in the Dickey-john GAC2100 for measuring MC of runner-type peanuts, 421 samples were measured with the meter and compared to oven MC data subsequently determined using ASAE Standard S410.1. Peanut moisture content for the peanuts according to the meter averaged 19.1% with a SD of 15.4%. Oven moisture contents had a mean of 17.3% and a SD of 8.5%. Means were significantly different (P = 0.001). A calibration equation was derived from capacitance, conductance, temperature, and test weight data provided by the meter and compared to oven MC data. Moisture contents calculated from the calibration equation had a 17.3% mean and an 8.5% SD equaling values for oven determined moisture contents. Results of the study indicate that the accuracy of the meter in predicting moisture content can be improved considerably utilizing currently collected data and the derived calibration equation developed.

Small-scale peanut shelling equipment has been designed and used to meet various needs and scales. A laboratory-scale sheller has been used by researchers to approximate the shelling outturns of a commercial shelling plant using 2 to 10 kg samples. A single commercial-sized sheller will have a shelling capacity up to 23 MT/hr. Commercial shelling operations utilize multiple shellers, each designed to shell a narrow range of peanut sizes. There are enterprises such as small seed processors or manufacturers in developing countries that need shelling equipment capable of processing 100 to 1000 kg of peanuts per hour with the capability of mechanically separating the hulls from the shelled material. A three-stage sheller was designed, fabricated, and tested to determine its throughput (kg/h), the efficiency of separating the hulls from the shelled peanut kernels, and sizing the shelled peanut kernels. The sheller had a maximum shelling rate in the first shelling stage of 1087 kg/h operating at 252 rpm. Approximately 93% of the peanuts were shelled in the first stage of shelling. An air velocity of 9.55 m/s was used to aspirate a mixed stream of peanuts and hulls and removed 97% of the hulls. The sheller was equipped with vibratory screens to separate the material into unshelled, edible sized peanut kernels, and oil stock.

A five-year study to investigate the potential interaction of conservation tillage with reduced irrigation amounts was conducted near Dawson, GA on peanut (Arachis hypogaea L.). Conventional tillage was compared to two conservation tillage programs (wide-strip and narrow-strip tillage) under four irrigation levels (100, 66, 33, and 0% of a recommended amount). Peanut yield did not exhibit a tillage by irrigation interaction as expected, although the main effects of irrigation and tillage were each significant by year due to weather variations. Peanut yield in narrow-strip tillage or wide-strip tillage were individually superior to conventional tillage in three seasons out of five, however only in one year did both conservation tillage systems outperform the conventional system. No detrimental effects on yields could be attributed to conservation tillage. Peanut quality and digging loss were dependent on the tillage by year effect as well as the main effect of irrigation. Irrigation increased total sound mature kernels (TSMK) 2% versus non-irrigated (0% irrigation level); tillage was not significant each year of the study but increased TSMK 2% in three of five years. Digging losses were greater in plots with increased yield potential such as those receiving irrigation. Net economic returns revealed a moderate trend towards sustained profitability under reduced irrigation levels through narrow-strip tillage and to a lesser extent, wide-strip tillage. Under conventional tillage systems, returns decreased with decreasing amounts of irrigation applied.

Peanut quality parameters were analyzed across four irrigation levels during the 2002 through 2007 crop years. The peanut quality parameters consisted of total sound mature kernels and sound splits (farmer stock grade), shelling outturn by commercial edible size, accept and reject kernels by commercial edible size, seed germination, and aflatoxin. The four irrigation levels consisted of a full level (100%), two reduced levels (66% and 33%), and a non-irrigated control. The research was conducted at the USDA/ARS National Peanut Research Laboratory's Multi-crop Irrigation Research Farm in Shellman, Georgia. By year, significant differences in the irrigation treatments depended upon precipitation distribution for the specific quality parameters. For the average over the six years in the study, farmer stock grade was not significantly different in the 100, 66, and 33% treatments while all were significantly higher than the non-irrigated control. Total shelling outturn and total edible outturn were higher in the 100 and 66% compared to the 33% and non-irrigated treatments. Total reject outturn and total oil stock were not significantly different in the 100, 66, and 33% treatments, while all were significantly lower than the non-irrigated control. Percent seed germination did not differ across treatments. Aflatoxin in total reject outturn and total oil stock was significantly higher for the non-irrigated treatment compared to the irrigated treatments.

Strip tillage with various crop covers in peanut (Arachis hypogaea, L.) production has not shown a clear yield advantage over conventional tillage, but has been found to reduce yield losses from some diseases. This study was conducted to determine pod yield and disease incidence between two tillage practices, five winter cover crops, three peanut cultivars, and three fungicide programs. Conventional and strip tillage treatments were implemented on a Greenville sandy loam (fine, kaolinitic, thermic Rhodic Kandiudults) near Shellman, GA. Five winter cereal grain cover crops (strip tillage) and a no-cover crop treatment were sprayed at recommended (1R), half recommended (0.5R) or untreated (0R) fungicide programs. Within peanut cultivars, leaf spot (Cercospora arachidicola Hori) intensity decreased as the number of fungicide applications increased; however, stem rot (Sclerotium rolfsii) incidence was the same for the 1R and 0.5R fungicide programs but increased 0R program. Conventional tilled peanuts developed more leaf spot compared with strip tillage. There was no difference in leaf spot ratings among winter crop covers. There was no difference in stem rot incidence with tillage or winter cover crop. There was no yield difference with peanut cultivar. Pod yield was the same for the 1R and 0.5R fungicide program (3867 kg/ha) but decreased at the 0R fungicide program (2740 kg/ha). Pod yield was greater with conventional tillage and strip tillage with black oats (Avena sativa L.) (3706 kg/ha) compared with strip tillage of other winter crop cover treatments (3358 kg/ha). Conventional tillage had more leaf spot, equal incidence of stem rot, and higher yield compared with strip tillage. The 0.5R fungicide program had the same yield compared with the 1R fungicide program implying a possible 50% savings on fungicide applications on well rotated fields with lower disease risk.

Peanut (Arachis hypogea L.) is typically sown in single or twin rows centered on 91-cm beds. A planter capable of sowing 8 peanut rows on a 182-cm bed was developed by USDA-ARS. This planting pattern optimizes plant spacing and may contribute to crop advantages. Management of soil borne diseases in peanut may be affected by planting patterns. Replicated field experiments were conducted in 2002, 2003, and 2004 at two locations each year near Dawson, Georgia to compare interactions of planting patterns and disease management programs. Three fungicide application regimes were factored over single row, twin row, and diamond planting patterns, for a total of 9 treatments. A block calendar schedule with 14-d intervals was compared with two weather advisory programs, including AU-Pnuts and an experimental version of AU-Pnuts using minimum daily soil temperature (MDST) as a guide for fungicide selection. The seeding rate of each planting pattern was 22 seed/m2. There were no planting pattern by fungicide program interactions. Twin row and diamond planting patterns were often superior in yield than single rows; however, diamond patterns did not yield better than twin rows. Incidence of peg, pod, and limb rot caused by Rhizoctonia solani and stem rot caused by Sclerotium rolfsii was not severe in any trial and was not affected by planting pattern. Despite low disease presence, the calendar program was consistently better for yield and overall disease control than the two advisory programs. Yield was similar for the three fungicide treatments in four of six experiments. Grade of twin row and diamond planted peanut was 0.7 points better than single row peanut over three years at one location. Net return based on crop value less fungicide program cost was more closely tied to yield than variable input costs for fungicide programs.

The objective of this research was to determine if bulk density of in-shell peanuts, called pod bulk density can be used to accurately estimate farmer stock grade factors such as total sound mature kernels and other kernels. Physical properties including pod or in-shell bulk density, pod size, and kernel size distributions are measured as part of the cooperative Uniform Peanut Performance Tests (UPPT). Using physical property data from three years (2002–2004) of UPPT, analysis of variance were performed to determine the effect of bulk density, location, year, peanut type, and cultivar on percent total sound mature kernels (TSMK), other kernels (OK), and farmer stock value (FSV). Results indicated that all effects in the model were significant in predicting both TSMK and FSV and accounted for most of the variation (R 2 50.80). Linear regressions of the UPPT (2002–2004) data (with pod bulk density as a single factor) showed that TSMK and FSV increased as pod bulk density increased with poor R 2 values (R 2 50.2). A second set of data collected during the 2005 peanut harvest by Federal State Inspection Service (FSIS) had similar results. Location and peanut type were highly significant factors in the variation of TSMK, OK, and FSV. Overall correlation of grade factors with pod bulk density, location, and type was poor (R 2 ,0.5). Based on these data, pod bulk density cannot be used to accurately estimate TSMK and OK for marketing farmer stock peanuts. Observed pod bulk density averaged for UPPT (all years) and FSIS was 316 kg/ m 3 for runner, 427 kg/m 3 for spanish, 491 kg/m 3 for valencia, and 258 kg/m 3 for virginia peanuts.

Proper crop rotation is essential to maintaining high peanut yield and quality. However, the economic considerations of sustainable cropping systems must incorporate commodity prices, production costs, and yield responses of the crops within the cropping system. Research was conducted at the USDA/ARS National Peanut Research Laboratory's Multi-crop Irrigation Research Farm in Shellman, Georgia to determine the average net returns of irrigated and non-irrigated cropping systems consisting of peanut (Arachis hypogea L.), cotton (Gossypium hirsutum L.), and corn (Zea mays L.). Five replicated cropping systems provided data on yield responses from irrigated and non-irrigated rotation sequences defined as: continuous peanuts (PPP), cotton/peanuts/cotton (CPC), corn/peanuts/corn (MPM), cotton/cotton/peanuts (CCP), and cotton/corn/peanuts (CMP). The peanut yield in the PPP rotation was 3300 kg/ha in the non-irrigated treatment. Non-irrigated yields in CPC and MPM rotation sequences were 3940 and 3890 kg/ha, respectively and yields in CCP and CMP rotation sequences were 4770 and 4710 kg/ha, respectively. The peanut yield in the PPP rotation was 4080 kg/ha in the irrigated treatment. Irrigated yields in CPC and MPM rotation sequences were 5280 and 5230 kg/ha, respectively and yields in CCP and CMP rotation sequences were 5940 and 6010 kg/ha, respectively. The economic returns of the cropping systems were analyzed for 3 different price level combinations. Production costs (variable and fixed) were obtained from partial budgets. Returns were defined as the 3 year average net returns of each cropping system and were calculated for each price level combination which resulted in 57 comparable average net returns for the irrigated and non-irrigated treatments. Net returns were influenced by rotation sequence, price, and irrigation.

Surface drip (SD) irrigation of field crops has been gaining interest in the farming community. However, rodent damage is one of the major drawbacks for SD acceptance. This research documents the cost of repairing drip tubing and effectiveness of several rodent control methods. Four sites were used to identify cost of repairing tubing. Treatments included untreated drip tubing, tubing that was lightly buried, sprayed with an insecticide or animal repellent, and edible rodenticide placed next to the tubing. Once a leak was found, it took an average of 4 minutes to repair the hole. Each repair had an average cost of $0.67 for labor and repair materials. This repair cost does not include time or transportation cost to find the leak. Rodent damage was the same in the untreated versus any chemical treatment tested. At Site 4, the animal repellent, RopelH, did have less rodent damage (2392 holes/ha) compared with the untreated (6049 holes/ha) however, the damage was extensive enough that it was more economical to replace than to repair the tubing. There was less rodent damage to the thin-walled tubing compared with the thickerwalled tubing. Drip tubing that was slightly buried had the best rodent control (5 holes/ha) compared with all other treatments (1771 holes/ha). One disadvantage of burying the drip tubing is removal. Strip tillage along with burying the drip tubing showed excellent resistance to rodent damage and appears to be a cost effective management tool for SD.

A two year study (2001 and 2002) was conducted at Sasser and Shellman, GA to determine the effects of planting pattern and plant population on the pod yield, market grade, and market value of peanut (Arachis hypogaea L.) when irrigated with subsurface drip irrigation (SDI). Soils were a Tifton loamy sand (fine-loamy, kaolinitic, thermic Plinthic Kandiudults) and Greenville sandy loam (fine, kaolinitic, thermic Rhodic Kandiudults) with 1% slope. Seeds were planted at recommended (20 seeds/m; 1.0R) and half the recommended rate (10 seeds/m; 0.5R) in a single and twin-row pattern. Plots were irrigated daily to replace estimated daily evapotranspiration (ETa). This study showed that twin-row plant pattern had 490 kg/ha higher pod yield compared with single-row pattern when irrigated using subsurface drip irrigation. The twin-row pattern also had a one percentage point increase in grade value (TSMK) compared with the single-row pattern. There was no difference in kernel size distribution with planting pattern. Twin-row planting had a $213/ha higher market value compared with single-row. There was no difference in yield on market value for seeding rate. This implies that it may be possible for a grower to plant in a twin-row pattern at half the recommended seeding rate without sacrificing net market value but may increase the risk of yield due to TSWV damage.

Tests were conducted to measure the effect of using bulk seed tenders to load peanut seed into planters. Treated seed were transferred using one of two bulk seed tenders, a pneumatic seed tender and a belt seed tender, and their quality compared to conventional bagged seed (control). Information recorded from each transfer of peanut included the mass of seed in each container and the time required to fill the container. Samples obtained during seed transfer were evaluated for mechanical damage and germination. Seed from both bulk tenders and control treatments were planted and field emergence evaluated periodically until 30 days after planting (DAP). Bulk handling increased mechanical damage when compared to the bagged seed. The pneumatic seed tender had the most damaged seed at 2.5%, compared to 1.1% damage by the belt seed tender. The amount of damaged seed was only 0.5% when bagged. Peanut seed loaded by the belt system had an average germination rate of 89% while germination of bagged and pneumatic treatments was 95 and 96%, respectively. Significant differences in emergence due to the seed handling treatment occurred throughout the first 30 DAP. Eleven DAP, field emergence of the bagged and belt conveyer seed was similar at 45% and 47% respectively, but fewer seeds from the pneumatic treatment had emerged (31%). Thirty DAP, field emergence in bagged (76% ) and the belt (75%) treatments were similar, and greater than the 69% that emerged in the pneumatically handled seed. Economic feasibility of investing in a bulk handling system for peanuts depends on several factors including investment cost, operating cost, and cost of tote bags versus labor and paper bag cost used in traditional seed handling. Farmers must have at least 324 ha for savings in labor and time to offset the capital cost of the bulk handling system.

Farmers' stock peanuts are processed into shelled peanuts using several basic sorting processes. After removal of foreign material and the shelling process, loose shelled kernels and shell...

The ability to measure plant water use directly could address a myriad of problems in peanut production from irrigation scheduling to aflatoxin management. One of the most effective methods of measuring plant water use is via the sap flow method; however this technique has not been tested in peanut in a field setting. In this study, sap flow collars were installed on peanut plants growing under overhead irrigation (OH), subsurface drip irrigation (SDI), and non-irrigated (NI) production. Using this experimental set-up the following objectives were addressed: 1) determine if the technique of sap flow measurement could be successfully utilized in peanut; 2) determine if daily peanut stem water flow, biomass partitioning, and carbon isotope discrimination differed among irrigation treatments, and 3) determine what environmental parameters were most closely correlated with peanut stem water flow. Peanut stem water flow was successfully measured during a two week period coinciding with active pod fill. Mean daily flow rates ranged from 4–6 g/ hr in irrigated treatments and from 1–2 g/hr in the dryland treatment. Significant differences among irrigation treatments existed in daily water use patterns, average daily water use, and cumulative daily water use based on plant sap flow. Soil moisture, soil temperature, and canopy surface temperature were significantly correlated with plant sap flow. Significant differences also existed among irrigation treatments in plant size with SDI plants having more leaf mass, longer internodes, and overall larger canopies than either the OH or NI plants. Even though SDI plants had much greater aboveground biomass than plants in the other treatments, yields did not differ between irrigation methods indicating SDI plants may have had lower water-use efficiencies than either OH or NI plants. However, seasonal water-use efficiency measurements represented by carbon isotope discrimination results did not definitively show this. This study has shown the efficacy of sap flow measurement in peanut and the potential applications of this technique in future irrigation studies.

Irrigated hectares for crop production in Georgia increased from 70,875 ha in 1970 to 587,250 in 2000. The majority of the increase was planted in peanut, corn, and cotton. In 1970, these crops accounted for 40,500 of Georgia's irrigated hectares, and in 2000, these crops totaled 465,750 irrigated hectares. Simultaneously, demand for water resources due to urban expansion and interstate litigation coupled with repeated drought are collectively threatening irrigation water supplies in the southeast U.S. peanut producing regions. A study was conducted during the 2001 to 2003 crop years to quantify the impacts of reduced irrigation amounts and different crop rotation sequences including peanut, corn, and cotton. On average, irrigated peanut pod yield was significantly increased by 906 kg/ha as compared to nonirrigated peanut yield. The affect of crop rotation on peanut yield was also significant. One year out of peanuts, in either corn or cotton, increased irrigated peanut yield an average of 1072 kg/ha over continuous peanut. Two years out of peanuts, in either corn or cotton, increased irrigated peanut yield an average of 2333 kg/ha over continuous peanut. In nonirrigated peanuts, crop rotation sequence had less affect on pod yield than did precipitation during the growing season.

A 2-yr study was conducted on a Tifton loamy sand (fine-loamy, kaolinitic, thermic Plinthic Kandiudults) soil near Sasser, GA during the 2001 and 2002 growing seasons to determine the effects of three plant row orientations (single, twin, and multi-row) and two plant populations on the pod yield, market grade, and stem rot disease incidence of peanut when irrigated with subsurface drip irrigation (SDI). Seeds were planted at the recommended rate [20 seeds/m; 1.0R (recommended rate)] and half the recommended rate (10 seeds/m; 0.5R). Plots were irrigated daily to replace estimated daily evapotranspiration (ETa). Twin row orientation had the highest pod yield with 5407 kg/ha compared with the other row orientations, which averaged 4897 kg/ha. Market grade (total sound mature kernels, TSMK) for the twin and diamond row orientation was 1% point higher (74.7%) compared with the single row orientation. Pod yield was 8.5% greater for the 1.0R seeding rate compared with the 0.5R seeding rate. Stem rot incidence was highest in the single row orientation and lowest in the diamond row orientation. Within the three row orientations, kernel size distribution characteristics showed jumbo kernels had mixed percentages, with medium and ones showing no differences. The 1.0R plant population did have 4.4 % more jumbo kernels than the 0.5R plant population. This study indicates that twin row orientation and planted at the recommended rate (1.0R) had the best pod yield and market grade compared with single row orientation when irrigated with SDI.

Previous research has shown that the farmer stock grade, lot weight, and market value could be accurately determined at kernel moisture contents greater than 10.5% without negative impact on either the producer or purchaser. In the 1998 and 1999 crop years, 686 farmer stock lots consisting of runner, Virginia, and Spanish types were graded and weighed at high moisture content (HMC), cured, and graded and weighed at low moisture content (LMC). The results indicated that LMC grade, lot weight, and lot value could be accurately predicted from HMC grade, lot weight, and lot value for individual farmer stock lots. However, the research did not address variability between HMC and LMC grade, weight, and values. In crop year 2001, a study was conducted in Georgia on runner-type peanuts to address variability in HMC and LMC grade, weight, and values. As farmer stock lots entered the buying point each lot was graded and weighed six times at HMC. The prediction equations estimated from the 1998 and 1999 studies were applied to the HMC values to obtain predicted grades, lot weights, and lot values. The lot was cured and graded and weighed six times at LMC and compared to the six predicted grades, lot weights, and lots values. Thirty-two farmer stock lots were included in the study. There were no significant differences in mean grade, lot weight, or lot value between the predicted and actual LMC values. Sound mature kernels and sound splits (SMKSS) differed by 0.07%. Mean lot weight differed by 7.7 kg (0.13%). Mean lot value differed by $20.11 (0.53%). Variability between predicted and actual SMKSS, lot weight, and lot value was not significantly different.