Tomato spotted wilt (TSW) is a common and serious disease of peanut (Arachis hypogaea L.) caused by Tomato spotted wilt virus (TSWV; family Tospoviridae, genus Orthotospovirus). Management frequently uses an integrated approach, with cultivar resistance and application of in-furrow insecticide as two critical components. In-furrow insecticides help suppress thrips, which can injure and stunt young growing plants and transmit TSWV, with postemergent application of acephate capable of providing additional thrips control. To examine effects of systemic insecticides (imidacloprid, imidacloprid plus fluopyram, phorate, and acephate) on TSW management, yield, and economic return across cultivar susceptibilities (susceptible, moderately susceptible, and resistant) in South Carolina, a meta-analysis was used to synthesize results from 32 studies conducted between 2009 and 2018. Although efficacy and magnitude of individual treatments varied with susceptibility, imidacloprid increased, whereas phorate generally decreased TSW incidence relative to nontreated controls. In-furrow treatments followed by acephate further reduced TSW incidence and increased profitability. All examined treatments improved yield compared with untreated peanuts except for susceptible cultivars treated with imidacloprid. Imidacloprid plus fluopyram increased yield more than imidacloprid alone for the susceptible group, although there was little difference between these treatments in association with moderately susceptible cultivars. When comparing individual applications, phorate was overall the most profitable option across susceptibilities, although imidacloprid plus fluopyram exhibited analogous profitability for susceptible cultivars. Results from this study can be used to assist producer selection of management options for TSW in peanut.

Late and early leaf spot are caused by Nothopassalora personata and Passalora arachidicola, respectively, and are damaging diseases of peanut (Arachis hypogaea L.) capable of defoliation and yield loss. Management of these diseases is most effective through the integration of tactics that reduce starting inoculum and prevent infection. The insecticide phorate was first registered in 1959 and has been used in peanut production for decades in-furrow at planting to suppress thrips. Phorate further provides significant suppression of Tomato spotted wilt virus infection beyond suppression of its thrips vector alone by activating defense-related responses in the peanut plant. From six experiments conducted from 2017 to 2019 in Blackville, SC, Reddick, FL, and Quincy, FL, significantly less leaf spot defoliation was exhibited on peanuts treated with phorate in-furrow at planting (26%) compared with nontreated checks (48%). In-season fungicides were excluded from five of the experiments, whereas the 2018 Quincy, FL, experiment included eight applications on a 15-day interval. Across individual experiments, significant suppression of defoliation caused by late leaf spot was observed from 64 to 147 days after planting. Although more variable within location-years, pod yield following phorate treatment was overall significantly greater than for nontreated peanut (2,330 compared with 2,030 kg/ha; P = 0.0794). The consistent defoliation suppression potential was estimated to confer an average potential net economic yield savings of $90 to $120 per hectare under analogous leaf spot defoliation. To our knowledge, these are the first data in the 61 years since its registration demonstrating significant suppression of leaf spot on peanut following application of phorate in-furrow at planting. Results support phorate use in peanut as an effective and economical tactic to incorporate to manage late and early leaf spot infections and development of fungicide resistance.

Late and early leaf spot, respectively caused by Nothopassalora personata and Passalora arachidicola, are damaging diseases of peanut (Arachis hypogaea) capable of defoliating canopies and reducing yield. Although one of these diseases may be more predominant in a given area, both are important on a global scale. To assist informed management decisions and quantify relationships between end-of-season defoliation and yield loss, meta-analyses were conducted over 140 datasets meeting established criteria. Slopes of proportion yield loss with increasing defoliation were estimated separately for Virginia and runner market type cultivars. Yield loss for Virginia types was described by an exponential function over the range of defoliation levels, with a loss increase of 1.2 to 2.2% relative to current loss levels per additional percent defoliation. Results for runner market type cultivars showed yield loss to linearly increase 2.2 to 2.8% per 10% increase in defoliation for levels up to approximately 95% defoliation, after which the rate of yield loss was exponential. Defoliation thresholds to prevent economic yield loss for Virginia and runner types were estimated at 40 and 50%, respectively. Although numerous factors remain important in mitigating overall yield losses, the integration of these findings should aid recommendations about digging under varying defoliation intensities and peanut maturities to assist in minimizing yield losses.

Late leaf spot, caused by Nothopassalora personata, is the most economically important fungal disease affecting peanut foliage in South Carolina and can result in combined management and yield loss costs of greater than 490 dollars/ha. Application of protectant fungicides is a critical part of effective integrated management under commercial production, and their strategic alternation and combination in management programs can provide enhanced control. Trials were conducted in Blackville, SC, from 2017 to 2019 to investigate whether combinations of prothioconazole with fluxapyroxad plus pyraclostrobin could provide more efficacious management of late leaf spot compared to either product alone. Two applications of 0.11 kg/ha prothioconazole with 0.05 kg/ha fluxapyroxad plus 0.1 kg/ha pyraclostrobin resulted in significantly (p < 0.05) less (24% to 42%) peanut canopy defoliation compared to the same number of applications of either product applied individually, with the combined application reflecting significant (p < 0.0202) synergism compared to component products as assessed through independent action methodology. An increased rate of fluxapyroxad plus pyraclostrobin application (0.1 and 0.2 kg/ha, respectively), with 0.16 kg/ha prothioconazole did not improve management relative to their combination at the examined lower rate (p = 0.89). Peanut yield was not adversely affected following combined applications. Cost-effectiveness of this combination depends on the actual disease intensity and yield potential of a given crop.

A study was conducted at Edisto Research & Education Center to quantify the effects of ground speed and conveyor speed on peanut digging losses using 2-row Amadas and KMC peanut diggers. The study was directed at studies at Edisto REC have focused on quantifying digging losses as a function of digging depth. Proper peanut digger setup and operation is critical to profitability—while manufacturers provide recommendations for proper setup and ground speed, there exist few published studies assessing these recommendations. In this study experiments were conducted to compare digging losses for four ground speeds (3.2, 4.8, 6.4, and 8.0 kph) at 100% relative conveyor speed ! "# $ tests were conducted independently for the two diggers using virginia type peanuts. For both diggers, digging losses increased as a function of ground speed with no significant difference in the 3.2 and 4.8 kph treatments. Results for the conveyor speed tests were consistent between the two diggers, with significantly higher losses at the 120% relative conveyor speed, but no significant differences across the other conveyor speeds. For the conditions of this test, results suggested that optimum ground speeds for peanut digging should not exceed 4.8 kph and that a range of conveyor speeds is acceptable, but conveyor speed should not exceed 110% of ground speed.

The digging and inversion process creates the most yield loss during peanut harvest. Even if the grower produces great yield from proper care and management of this crop it can quickly be lost from the improper settings of the peanut digger. Although all losses cannot be prevented during the process a great deal of experienced yield losses are generally avoidable. Proper setting of the peanut digging angle for the soil texture is among the most important factors in optimizing yield losses during the inversion process. It is common practice for producers to set the peanut digger for the finest soil texture in the field. This is in part due to difficultly to adjust the top link every time the soil texture changes within a field, as well as the misconception that it is better to dig more aggressively. Tests conducted at the Clemson University Edisto Research and Education Center demonstrated that improper top link settings across soil textures within a field led to higher digging losses. Digging losses ranged from 3.3 to 10.9% of potential yield in the sand soil texture, 5.8 to 15.7% in the medium texture, and 12.3 to 24.1% in the clay soil texture. The data indicated that there was an optimum top link setting for each soil texture, with increased losses at both shallower and deeper depths. Average recoverable yield was statistically less in the sand texture zone (4,457 lb ac -1 ) than in the medium (5,149 lb ac -1 ) and clay (4,891 lb ac -1 ) texture zones. Over-mature and diseased digging losses were greatest for the clay texture, but not statistically different from those for the sand and medium texture zones.

A variable depth peanut digger was developed for use in assessing the ability to reduce digging losses as a function of digging blade angle and on-board remote sensing. Soil electrical conductivity (EC) data were used to divide a field into three zones, ranging from sand to clay texture. A computer controlled hydraulic top link was provided for adjustment of top link extension and therefore the digging angle. The optimal top link position was determined for each of the three zones by visual observation of the windrow and these three top link positions were applied in six replications across all three zones. Additional top link positions were conducted in the clay and sand soil zones, operating shallower than optimal in the sand texture zone and deeper than recommended in the clay texture zone. Average digging losses (dry basis) ranged from 156 to 556 kg ha-1 (138 to 496 lb ac-1) in the sand texture zone, 330 to 854 kg ha-1 (294 to 761 lb ac-1) in the medium texture zone, and 674 to 1,190 kg ha-1 (601 to 1,061 lb ac-1) in the clay texture zone. Within each texture zone, the optimum indicated soil draft force, as indicated by a load shank positioned behind the center coulter, increased from coarse to fine soil textures. Hydraulic top link pressure indicated potential for use as an on-the-go feedback-based control for optimizing digging depth, with minimized digging losses occurring in the same range of pressure across two soil textures. A digging blade depth gauge was effective in on-the-go indication of blade depth and demonstrated potential for on-the-go digging angle prescription, but only where incomplete canopy coverage existed. The developed prototype demonstrated the potential for $47 ha-1 ($19 ac-1) in yield loss savings with an estimated break-even payoff acreage of 109 ha (269 ac).

A commercially available Ag Leader® impact plate grain yield monitor kit was adapted to be installed on an Amadas M2108 4-row pull type peanut combine to evaluate its accuracy in yield prediction for two different mounting configurations and to assess the benefits of providing yield prediction correction by sensing the pneumatic conveyance air pressure. For the two impact plate configurations, the yield monitor load sensor was mounted onto a curved bar rack installed at an elbow in the clean peanut conveying duct just prior to its entrance into the basket. In the first configuration, the bar rack was installed to float in the elbow section of the duct, mounted solely to the load sensor and not touching the duct on any sides. In the second configuration, the upper edge of the bar rack was hinged against the duct, allowing the impact of peanuts to impart a torque on the bar rack assembly. In the floating configuration, average absolute error of yield predictions from 17 loads was 12.7% and in the hinged configuration, average absolute error of yield predictions from 8 loads was 6.6%. Observations made during the study indicated that the hinged configuration was less likely to collect, or wedge, trash between the bar rack and the duct, which may explain its greater accuracy in yield predictions. Using the floating impact plate configuration, inclusion of fan air pressure as an additional independent variable in a multiple linear regression equation, load weight prediction errors were 9.8% across 9 loads, compared to 11.6% with impact plate sensing only across the same loads.

A variable depth control peanut digger was developed as an automated system to control the three point hitch top link position on a 2-row KMC peanut digger, aimed at reducing peanut digging losses across a variety of soil textures. Investigation was performed to determine if top link position, and therefore the digger blade angle, can be prescribed as a function of soil electrical conductivity (EC) prescription maps, relating to soil texture, or on-the-go sensor-based feedback control. Sensors included for evaluation of on-the-go depth control included: (1) load cells fixed to ripper shanks for direct measurement of soil draft force; (2) a pressure transducer mounted to a hydraulic top link for measurement of digger reactant force; and (3) a rotary potentiometer mounted to a depth gauge for indication of blade depth. A linear potentiometer was included to indicate extension of the hydraulic top link. The measures of soil draft force were included to evaluate on-the-go indication of soil texture, because proper digger top link adjustment has been indicated to be dependent on soil texture. The hydraulic top link position was adjusted using a computer-operated directional control valve. EC mapping was used to divide a field into three texture zones, with each soil texture zone divided into 12 m (40 ft) long 2-row plots. Soil texture measurement, as indicated by hydrometer testing, demonstrated a good relationship with soil EC. On-the-go data from the front soil draft force sensing shank, top link pressure transducer, and blade depth gauge all correlated with digger setting, increasing in value with decreasing top link extension, with the top link pressure transducer statistically showing the most promise for use as a feedback-based control sensor. The results indicated that soil EC maps coupled with on-the-go sensor-based adjustment is feasible for prescription of variable depth digger settings.

Twin row peanut production was initially introduced to take advantage of production benefits noted in narrow, single row studies, while still accommodating typical machinery involved in peanut production. Studies on twin row peanut production have been conducted since at least the early 1980s and many report increased yields and reduced weed pressure when compared to single row studies. Because the conventional peanut harvest is a two stage process where the plants are first dug and then combined several days later, there are two opportunities for yield losses. This study compares the yield losses at digging for twin row and single row peanuts of two virginia type varieties, Bailey and Champs. Digging losses were quantified as “above ground” and “below ground” losses. Peanuts were planted and dug using RTK navigation to reduce operator induced errors. Mean above ground, below ground, and total digging losses were higher for twin row than for single row configurations across both varieties, but only statistically different for percent above ground losses and percent total digging losses in the Champs variety. Single row mean pod production was higher than that for twin row, but single row mean harvested yield was lower than that for twin row, although not statistically different. The results of this study were not statistically conclusive, but indicate that despite greater pod production and lower digging losses for single row than that for twin row peanuts. This suggests that combining losses for the single row peanuts in this study may be dominant in accounting for total harvest losses. Further study is needed to verify.

Abstract Susceptibility to viral and fungal diseases is a major factor limiting profit in the production of virginia-type peanuts (Arachis hypogaea L.) in the South Carolina coastal plain. Field tests were conducted over a three-year period (2006–08) to evaluate the disease resistance of 47 experimental virginia-type breeding lines and eight cultivars. Relative to commercially available standards, cultivar Bailey (recently released by N. C. State Univ.), three sister lines (N03088T, N03089T, and N03090T), and N03091T were found to have consistently less susceptibility to tomato spotted wilt tospovirus; late leaf spot, Cercosporidium personatum (Berk. and Curt.) Deighton; and stem rot, Sclerotium rolfsii Sacc. The level of field resistance measured for these three diseases was comparable to that of a resistant runner-type cultivar, Georgia-03L. Yield was highly correlated with multiple disease resistance, and yield performance of some resistant lines exceeded the best commercial standard cultivars under reduced fungicide programs. Potential negative attributes of Bailey, its sister lines, and N03091T were a greater susceptibility to leafhopper injury, Empoasca fabae (Harris), and a relatively larger plant size at maturity, without well defined rows to facilitate digging. Other lines that demonstrated reduced susceptibility to both tomato spotted wilt and stem rot were N03005J and N02009. Although only evaluated in the last test year, five Univ. of Florida lines (FLMR7, FLMR9, FLMR12, FLMR14, and FLMR15) and Georgia-08V (recently released by the Univ. of Georgia) also showed some reduction in stem rot susceptibility relative to the standard (cultivar NC-V 11). Equally important, many experimental lines were identified with significantly greater disease susceptibility than current commercial cultivars. Under South Carolina production conditions, these lines would be poor candidates for advancement. Deployment of the multiple disease resistance found in these experimental cultivars offers several potential benefits beyond direct yield improvement: reduction of fungicide input costs for both foliar and soil disease control, prolonging the utility of currently available fungicides, and reduction of weather related harvest risk by allowing earlier initial planting dates.

There are anecdotal claims that some fungicides cause physiological peg strength enhancement beyond mere suppression of the diseases, which can reduce peanut peg strength. We tested eleven...