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Insecticide efficacy often varies by location and year. Many factors can influence an insecticide's efficacy, but an often-overlooked factor is water quality in a carrier solution. Multiple experiments were conducted to evaluate the impact of water hardness and pH on chlorantraniliprole efficacy for controlling corn earworms. In the first experiment, leaf dip assays were conducted to evaluate the effects of water pH on chlorantraniliprole. Serial dilutions were used to achieve the concentration of 6 ng/mL of chlorantraniliprole in 3 different water samples with a pH of 6.47, 8.31, and 9.12, respectively. Larvae were placed on 0.5-in. leaf discs after drying and observed for mortality 48 hours after application. In the next experiment, leaf dip assays were conducted similarly but with water at a hardness of 11 ppm, 178 ppm, and 430 ppm, respectively. A third experiment was conducted in the greenhouse where Prevathon® at a rate of 14 oz/ac was mixed with water with a hardness of 10.9 ppm, 178 ppm, and 430 ppm, respectively, then applied to soybean plants. Leaves were pulled from the soybean plants at 1, 7, 21, 28, and 35 days. Larvae were placed on 0.5 in. leaf discs and checked for mortality at 48 hours. In the final experiment, water samples with a hardness of 10.9 ppm, 178 ppm, and 430 ppm, respectively, were mixed with Vantacor® 1.2 oz/ac, Intrepid Edge® 5 oz/ac, Denim® 8 oz/ac, and Besiege® 7 oz/ac then sprayed on soybeans and evaluated at 4, 7, and 10 days after treatment for the control of corn earworm. The hardness leaf dips and pH leaf dips showed that as water hardness or pH increased, the % mortality decreased. In the greenhouse and field trials, there were no significant differences. [ABSTRACT FROM AUTHOR]

Bollworm (Helicoverpa zea, Bodie) is currently the second most damaging insect pest of cotton in Arkansas. The primary method used to control bollworms in cotton is the use of transgenic Bacillus thuringiensis (Bt) technologies. Resistance to dual-gene cotton cultivars has recently been documented in bollworm, and results indicate that supplemental foliar applications may be needed to manage high populations. Research was conducted in 2021 and 2022 at Tiller (Drew County), Arkansas, to evaluate the efficacy of several Bt technologies. Results suggest that sprayed dual-gene cultivars had similar levels of damage to unsprayed three-gene cultivars. All three-gene treatments, sprayed non-Bt, and sprayed Bollgard II, had similar yields, which were greater than unsprayed non-Bt and unsprayed Bollgard II. These data suggest that dual-gene cultivars may need a supplemental foliar application for bollworm. [ABSTRACT FROM AUTHOR]

Transgenic Bt cotton has not eliminated the need for supplemental foliar insecticidal applications. Prior to the introduction of transgenic cotton expressing insecticidal proteins derived from Bt, foliar insecticides were used as the main control method of Helicoverpa zea. Due to high technology fees and documented cotton bollworm resistance to transgenic Bt technologies, supplemental foliar applications may be required to manage high populations of H. zea. Despite additional input costs, growers could achieve greater profits with an insecticide application when bollworm threshold is exceeded. Research was conducted in 2022 in Drew County, Arkansas, to evaluate several insecticides, including Prevathon, acephate, and bifenthrin, for efficacy and residual control of H. zea on multiple Bt cotton technologies. Results suggest that sprayed Bollgard II had similar levels of damage to all Bollgard III treatments. All Bollgard II treatments, sprayed Bollgard II, and non-Bt plots receiving a second insecticide application had similar yields, which were greater than unsprayed non-Bt and non-Bt sprayed with Prevathon or acephate plus bifenthrin. [ABSTRACT FROM AUTHOR]

Tarnished plant bug (TPB) (Lygus lineolaris) is the number one insect pest of cotton in Arkansas, causing square loss, deformed flowers, and damaged bolls, ultimately reducing yield. Tarnished plant bug is difficult to control, and growers average 4-6 insecticide applications per year targeting TPB. Multiple insecticides are available for control of TPB, but resistance to some modes of action has been documented in this pest. Thryvon is a new cotton biotech trait that will provide season-long protection against TPB and thrips species, reducing the need for some insecticide applications. Cotton cultivars incorporating ThryvOn express the Cry51Aa Bt proteins that have been proven to provide some suppression of TPB. A study was conducted during the 2022 growing season at the University of Arkansas System Division of Agriculture's Lon Mann Cotton Research Station in Marianna to determine if the efficacy of TPB insecticides was different on ThryvOn and non-ThryvOn cotton. Insecticide treatments included bifenthrin (6.4 fl oz/ac), acephate (0.75 lb/ac), novaluron (6 fl oz/ac), sulfoxaflor (1.5 oz/ac), and thiamethoxam (2 oz/ac). Plots were sampled at 3, 7, and 11 days after the first application and 4, 7, and 11 days after the second application. A general trend was observed that insecticide efficacy was improved with all insecticides in ThryvOn cotton when compared to non-ThryvOn cotton. This same trend was observed for square retention and yield. [ABSTRACT FROM AUTHOR]

Insecticide efficacy often varies by location and year. Many factors can influence an insecticide's efficacy, but an often-overlooked factor is the quality of water in a carrier solution. Multiple experiments were conducted to evaluate the impact of water quality on insecticide efficacy. In the first experiment, leaf dip assays were conducted with Transform, Orthene, Bidrin, and Centric, each mixed in three waters with hardness levels of 10.9, 178, and 430 ppm. Transform, Orthene, Bidrin, and Centric were also mixed in three waters having pHs of 6.47, 8.03, or 9.27, with an untreated check. Adult plant bugs were placed on a one-half-inch leaf disc after drying, and mortality was observed at 48 hours. In the second experiment, Transform 1.5 oz/ac, Orthene 0.75 lb/ac, Bidrin 8 oz/ac, and Centric 2 oz/ac were each mixed in three waters with hardness levels of 10.9, 178, and 430 ppm, then applied to cotton for tarnished plant bug control. In the third experiment, Transform 1.5 oz/ac, Orthene 0.75 lb/ac, Bidrin 8 oz/ac, and Centric 2 oz/ac were each mixed in three waters with pHs of 6.47, 8.03, and 9.27, then applied to cotton and evaluated for tarnished plant bug control. In the fourth experiment, Bidrin was mixed with waters with a pH of 6.4 and 9.1. AMS, Quest, Smoke, Diversify, and an experimental compound were each added to water with a pH of 9.1 prior to the addition of Bidrin, then applied to cotton. In the fifth experiment, Bidrin was mixed with water having a hardness of 10.9 ppm (soft water) or 430 ppm (hard water). AMS, Quest, Smoke, Diversify, and an experimental compound were each added to water with a hardness of 430 ppm, Bidrin was then added, and the solutions were then applied to cotton. No differences in treatments were present in the first, second, or third experiments. In the fourth experiment, the experimental compound and Quest provided better control than Smoke at 4 days after treatment (DAT). At 7 DAT, Smoke continued to provide the poorest control. In the fifth experiment, there were no differences at 3 DAT, but at 7 DAT, Diversify provided better control than the soft water. [ABSTRACT FROM AUTHOR]

Rice stink bugs (RSB) are a major pest of rice after panicle emergence in Arkansas. Pyrethroids, particularly lambdacyhalothrin (lambda), have been the primary insecticide used to control RSB for the past 15 years. Recently, there have been increasing concerns of potential pyrethroid resistance. Lambda control failures have been documented in Arkansas in late-season RSB populations since 2019. Populations of RSB's were collected in May, June, July, and August throughout the state in 2021 and 2022. Lambda was applied to petri dishes at multiple rates to determine the efficacy of RSB. Fiftyfour collections were made throughout 2021 and 2022. Over the fifty-four populations that were sampled, percent mortality ranged from 66% to 68% between the 1x and 4x rates of lambda. Slightly higher mortality was observed in May as compared to the other months collections were made. These preliminary results indicate that pyrethroid insecticide resistance may become an increasing problem in Arkansas, and future management strategies need to be evaluated. [ABSTRACT FROM AUTHOR]

Rice stink bug (RSB) is a major pest of rice, feeding on developing grain, which can lead to yield and quality losses. Few insecticides are currently available to rice producers for rice stink bug management. Lambda-cyhalothrin (lambda) is the most common insecticide used to manage RSB due to its low cost. Over 50% of Arkansas rice acreage is treated with lambda for control of RSB annually. Other options, such as Tenchu (dinotefuran), are effective for control but not at a competitive price point. The dependency on lambda for RSB control, and control issues observed in Louisiana and Texas, raises concern for RSB resistance in Arkansas. New options for RSB need to be evaluated to determine effective alternatives to lambda. Foliar efficacy field trials were performed in 2021 and 2022 to compare insecticides for efficacy and residual control of rice stink bug. Sweep net samples were taken at 3, 7, 10, and 14 days after treatment (DAT) to monitor RSB efficacy. Excluding the pyrethroids, all other insecticides provided adequate control of RSB at 3 and 7 DAT. Only Tenchu and Endigo ZCX provided adequate control of RSB at 10 and 14 DAT. [ABSTRACT FROM AUTHOR]

Grape colaspis (GC) and rice water weevil (RWW) are the most common and destructive insect pests of early-developing rice in the Southern US. The larvae of both pests are the main contributors of injury, feeding on the plant roots and leading to yield losses. The most common method of control for both pests is the use of insecticide seed treatments (IST). Foliar insecticide applications are also a control tactic for RWW but are not effective for grape colaspis. In 2022, research was conducted at two locations to compare ISTs and IST combinations for management of these pests on both conventional and hybrid rice cultivars. Further, varying rates of Dermacor were evaluated to determine if the rate could be reduced and still achieve adequate control while reducing the overall cost. All insecticide treatments provided greater control of RWW compared to the untreated check. Other than the hybrid cultivar at the Stuttgart location, no differences were observed among Deramcor rates. A general trend was observed that the higher rates of Dermacor had lower RWW densities compared to lesser rates. Results from this research suggest that reduced rates of Dermacor provide similar control to full rates which could potentially lower the cost of the overall seed treatment package. [ABSTRACT FROM AUTHOR]

Experiments were conducted from 2020-2022 to evaluate effectiveness of insecticides and application methods for control of rice billbug. An insecticide seed treatment study was conducted using neonicotinoid and diamide insecticide seed treatments alone and in conjunction with one another to assess potential suppression of rice billbug injury. Additionally, a study was conducted to observe if foliar insecticide applications could suppress rice billbug. Multiple sampling methods were tested to correlate rice billbug damage to grain yield. At the panicle initiation growth stage, rice was sampled by counting total tillers and damaged tillers in five linear feet per plot. After panicle emergence, the number of blank heads per five linear feet within a plot was also recorded. Sampling rice prior to heading shows a general trend between treatments, but optimal timing needs to be evaluated. In the insecticide seed treatment study, a general trend was observed. Plots with a seed treatment containing a neonicotinoid in combination with a diamide product, resulted in yields greater than the untreated check or any single chemistry insecticide seed treatment. Rice seed treated with only a diamide resulted in greater yields when compared to a neonicotinoid treatment. Finally, no differences were observed when two neonicotinoids were applied to rice seed compared to a single neonicotinoid alone. All insecticide seed treatments significantly increased yield when compared to the untreated check. Results from the foliar insecticide study showed that greatest yields were observed with a combination seed treatment compared to any foliar insecticide applied regardless of timing. [ABSTRACT FROM AUTHOR]

The utilization of semiochemicals such as insect pheromones has proven successful in monitoring regimes for U.S. agriculture in the last half-century. The rice billbug, (Sphenophorus pertinax, Chittenden), has recently become a concern to mid-Southern U.S. rice producers implementing a potential cost-saving, production system. Furrow-irrigated rice hectare has continued to increase for the last five years. Lack of research on the rice billbug has raised concerns as the furrowirrigated rice system gains popularity. Further understanding, and evaluations of control tactics have become a priority for entomologists in rice-growing regions of the U.S. Extraction and implementation of pheromone targeted for rice billbug, could allow timely control measures to take place and potentially reduce the amount of injured rice across the field. In this study, volatile semiochemicals extraction, and Y-tube choice tests were conducted at the University of Arkansas System Division of Agriculture's Department of Entomology in Fayetteville, Ark. Volatiles were extracted from rice billbug populations caught during the 2021 and 2022 growing season across the state of Arkansas. Three different chemicals (volatiles and closely related compounds) were evaluated for their attractancy to male and female rice billbugs. Findings from these preliminary studies show that a significant response to tested semiochemicals was observed. Blends A (4-Methyl-2-pentanol) and B (2,6-Dimethyl-4-heptanol) were more frequently selected compared to blend C containing tert-Butyl hydroperoxide. Blend C also suggested signs of repellency in males, and higher attraction in females. However, further research is needed in this direction as developing a semiochemical-based effective monitoring regime could potentially aid growers in economically and efficiently controlling rice billbug in future crops. [ABSTRACT FROM AUTHOR]