Tobacco thrips (Frankliniella fusca) are a key early-season pest of peanut and transmit tomato spotted wilt virus (TSWV), both of which can reduce yield when not managed effectively. This study evaluated the effects of peanut cultivar and at-plant insecticide on thrips injury, TSWV incidence, canopy development, nematode (Meloidogyne arenaria) infestation and yield in Alabama from 2023 to 2025. Two cultivars (GA-06G and GA-12Y) were planted with four treatments: a non-treated control and at-plant applications of aldicarb (7.8 kg/ha), phorate (5.6 kg/ha), and oxamyl (1.3 L/ha). Thrips injury (0-5), seedling vigor (0-100), fractional green canopy cover, TSWV incidence and nematode population estimates were done at various timings through 56 days after planting (DAP) and yield was collected at the end of the season. At-plant insecticides reduced thrips injury compared to the non-treated control. Seedling vigor was greatest in Georgia-12Y peanuts and where AgLogic was applied. TSWV was greater and fractional green canopy cover was lower in non-treated plots and where GA-06G was used. Peanut root knot nematode egg counts did not differ among treatments. Yield was greater in GA-06G overall and where at-plant insecticides were applied. These results demonstrate that at-plant insecticides contribute to thrips and TSWV suppression and protect yield in Alabama peanut production.
When the final population of peanut is too low, yield can be affected. Supplemental replanting is a proven method to increase the population if managed properly. Experiments were conducted in Tifton, GA in 2017-2019. Sub-optimal plant populations were established, then expanses of row were voided to determine whether replanting would adequately replace the gaps. In random sections of row, plants were removed in consecutive lengths of 61, 122, or 183 cm, either once or twice per row. Each gap scenario implemented three different supplemental replant scenarios: (a) none (“no-replant”), (b) replant only in the gap (“gap-only”), and (c) replant the entire row-length (“full-row”). The “full-row” replant provided the most consistently positive results for yield, grade, and tomato spotted wilt (TSW) incidence. Yield was 14-61% greater than “no-replant” and grade (74.8% total sound mature kernels) was greater than “no-replant” (73.3%) and “gap-only” (73.0%). Reduced TSW was also observed with “full-row” replanting (26%) than in “no-replant” (35%) and “gap-only” (33%) management. The “full-row” replant is a viable strategy to maximize outputs and minimize risks. However, “gap-only” replanting successfully improved yield over not replanting when gaps exceeded 122 cm and at least 18% of the row was missing. This could be a viable alternative if seed or time is limited.
The peanut burrower bug (Pangaeus bilineatus) is a sporadic but economically important insect pest of peanut in the southeastern United States. In the absence of effective insecticidal control options, host plant resistance may be the best sustainable management strategy. However, little information is available on cultivar susceptibility to peanut burrower bug. Field experiments were conducted in Georgia from 2016 to 2020 to compare peanut burrower bug feeding injury among commercial peanut cultivars and to determine the force required to penetrate the pod hull (i.e. hull strength) as a potential resistance mechanism. Kernel injury was assessed as the weight of percent injured kernels that exhibited feeding lesions, and penetration force was measured on pods from selected cultivars using a digital force gauge. Injury levels varied significantly over the years, with the greatest injury occurring in 2017 and 2018. In both of these years, the widely planted cultivar Georgia-06G sustained the greatest injury compared to several other cultivars. Pod penetration force differed among cultivars; however, increased hull strength was not consistently associated with reduced feeding injury. These results indicate that susceptibility of peanut cultivars to peanut burrower bug feeding is not explained by hull strength alone and is likely influenced by multiple host plant traits. Identification of cultivars with reduced susceptibility may help mitigate risks in fields with a history of peanut burrower bug injury and guide future efforts to develop resistant germplasm.
In Virginia, prohexadione calcium (PC) has been used for decades in peanut (Arachis hypogaea L.) production to reduce vine growth for visually guided digging. Along with growth suppression, PC has been reported to improve yield and physiological stress responses of numerous field crops, vegetables, and ornamental crops. However, in peanut, PC’s effect on plant physiological and agronomic characteristics is inconclusive. This could be attributed to several factors including variable genotypic responses and potential PC effect on maturity. In 2022 and 2023, replicated trials were established at the Tidewater Agricultural Research and Extension Center in Suffolk, VA (USDA Zone 7b), to evaluate the effect of PC on yield, seed characteristics, and pod maturity on commercially available peanut cultivars in Virginia, using a unique site-cultivar scenario. PC was applied at the recommended rate of 140 g ai/ha, at 50% and 100% canopy closure. Maturity was determined by pod mesocarp color several times during the growing season(s) starting at 100 d after planting until digging and expressed as pod maturity index, i.e. the ratio of orange, brown, and black pods from all pods within a sample of approximately 200 pods. Data indicate PC did not affect peanut maturity and 100 SMK weight in 2022 or 2023 but influenced pod number per plant in 2023. Pod yield was improved by PC applications in 2023, a year with twice as much precipitation as 2022; and site-cultivar and PC interaction was significant in 2023. In 2023, yield was increased by PC for the site planted with Bailey II and NC 20 and remained non-significant for Emery, Sullivan, and Walton. Results suggest that the PC effect on peanut yield was weather and site-cultivar dependent.
The use of spray drones for applying pesticides in row crops has increased rapidly in recent years. Consequently, there is growing interest among applicators and growers in their use for fungicide applications in peanut; however, limited information is available on their spray performance and the effectiveness of disease management in peanut. Therefore, studies were conducted in 2023 and 2024 to evaluate spray deposition within the peanut canopy and the efficacy of fungicides applied using a commercial spray drone (DJI T30), and to compare it with traditional ground sprayer applications. The spray deposition within the peanut canopy was assessed at different intervals (45, 60, 90, and 120 days after planting) during the season, while fungicides were applied using both the ground sprayer and spray drone throughout the season. Disease control and yield were recorded at harvest to assess the efficacy of the fungicide applications. The ground sprayer provided greater spray coverage and droplet density than the spray drone within the peanut canopies. The spray drone also exhibited greater variability in spray deposition within the swath than the ground sprayer. For both the ground sprayer and the spray drone, the spray coverage and droplet density decreased from the upper to the lower canopies. Despite reduced coverage and greater in-swath variability, the spray drone showed similar disease control for leaf spot and stem rot as the ground sprayer in 2023. Due to low disease pressure, the sprayer type had no effect on disease control in 2024. Peanut yield was comparable between the treated and non-treated (no fungicides) plots during both years. The findings suggest that spray drones can be a viable technology for timely fungicide applications in peanut; however, their efficacy under high disease pressure needs to be evaluated. Future research should also investigate the impact of application parameters, such as spray volume and droplet size, on spray penetration and disease control.
