The fall armyworm, Spodoptera frugiperda (J. E. Smith), is a sporadic pest with a diverse host range. This insect occasionally causes damage to cotton across the United States from the Rocky Mountains to the East Coast. Fall armyworm has been problematic in cotton due to its overall tolerance to many insecticide use strategies and difficulty in finding and surveying field infestations with sampling protocols. A review of insect biology, description of life stages, behavior and host strain identification, injury to cotton, and potential management options for the southeastern United States are presented.

Alternative methods of rice (Oryza sativa L.) irrigation are gaining increasing popularity across the U.S. Mid‐South, but an allowable soil moisture deficit stress has not been defined. This study was conducted in 2018 and 2019 to determine the soil moisture threshold for furrow‐irrigated rice (FIR) and alternate wetting and drying (AWD) rice production systems to minimize irrigation water use while maximizing grain and milling yield. Soil moisture thresholds of −15, −30, and −45 kPa, as determined by Watermark sensors at a 10‐cm depth in the top third of the field, were compared with conventional flood rice (CFR) on a Calloway silt loam and a Sharkey clay in eastern Arkansas. Soil moisture threshold had no effect on grain or milling yield across irrigation thresholds; however, the bottom third of FIR, where a flood was held, consistently produced higher grain yield (10,652–10,965 kg ha⁻¹) than the top third (9,442–9,722 kg ha⁻¹). Significant differences in irrigation water use efficiency (IWUE) were achieved under AWD and FIR. The IWUE did not differ across AWD irrigation thresholds but was 58.1–103.8% greater than that of CFR. The −15 and −30 kPa FIR thresholds did not improve IWUE, but using a −45 kPa irrigation threshold resulted in a 42.7% greater IWUE than CFR and 66.0% greater than the −15 kPa threshold. Results suggest that using a −45 kPa irrigation threshold at the 10‐cm depth can potentially maintain grain and milling yield while increasing IWUE under AWD and FIR.

This study investigated rice irrigation water use in the University of Arkansas Rice Research Verification Program between the years of 2003 and 2012. Annual irrigation water use averaged 763 mm (30.0 in.) over 10 years. A significant (40%) water savings was found for rice grown using a zero-grade irrigation system [486 mm (19.1 in.)] compared to contour-levee or straight-levee systems. No differences in irrigation water use were found between contour-levee systems [814 mm (32.1 in.)] and straight-levee systems [822 mm (32.4 in.)]. Surface water irrigators used significantly less irrigation water [624 mm (24.6 in.)] than groundwater well fields [786 mm (30.7 in.)] and cost US$77.51 less per hectare (US$31.37 less per acre) to operate. Diesel pumps cost significantly more [$88.38/acre ($218.29/ha)] to operate than electric pumps [$58.69/acre (145.96/ha)] (P=0.02), although fields that used diesel as an energy source averaged 152 mm (6.0 in.) less irrigation water than electric pumps. Arkansas produ...

Cotton, Gossypium hirsutum (L.), plants expressing insecticidal crystal (Cry) proteins of Bacillus thuringiensis (Bt) Berliner are planted on significant acreage across the southern region of the United States. Fall armyworm, Spodoptera frugiperda (J. E. Smith), can be a significant cotton pest in some years, but this species has not been a primary target of Bt cotton technologies. The objective of this study was to quantify fall armyworm larval survivorship and fruiting form injury on transgenic cotton lines expressing Cry1Ac (Bollgard), Cry1Ac + Cry2Ab (Bollgard II), and Cry1Ac + Cry1F (WideStrike) Bt proteins. Larval survivorship and fruiting form damage of fall armyworm on Bollgard, Bollgard II, WideStrike, and non-Bt (control) cotton lines were evaluated in no-choice field studies. Fall armyworm (third instars) were placed on flower buds (squares), white flowers, and bolls, enclosed within a nylon mesh exclusion cage, and evaluated at selected intervals after infestation. Exposure of fall armyworm larvae to Bollgard cotton lines generally resulted in no significant effects on survivorship compared with larvae exposed to the non-Bt cotton line. Survivorship and plant injury by fall armyworm on Bollgard II cotton lines was variable compared with that on non-Bt cotton lines, and significant differences between treatments were inconsistent. Fall armyworm had significantly lower survivorship and caused less plant injury on WideStrike cotton lines than on non-Bt cotton lines across all plant structures. Development and survivorship of fall armyworm larvae on these cotton lines also were evaluated in no-choice laboratory assays by offering the previously described fruiting forms to third instars. Bollgard II and WideStrike cotton lines significantly reduced fall armyworm development and survivorship compared with those larvae offered non-Bt tissue. These results suggest that differences exist among selected Bt cotton technologies in their performance against fall armyworm.

Field experiments were conducted in 2013 and 2014 to evaluate the effect of insecticide seed treatments on exposure of young conventional rice to reduced rates of glyphosate and imazethapyr. During the two-year study, “Roy J” rice seed was treated with CruiserMaxx® Rice, thiamethoxam plus fungicide, or a fungicide-only treatment. Subsequently, glyphosate (Roundup PowerMax®) at 39.42, 78.76, or 157.54 g ae/ha or imazethapyr (Newpath®) at 4.39, 8.74, or 17.49 g ai/ha was applied at the 2- to 3-leaf growth stage of rice. Results in 2013 indicated that rice plants from seed treated with CruiserMaxx Rice exhibited significantly less injury 1, 3, and 6 weeks after either imazethapyr or glyphosate was applied in comparison to the plants having fungicide-only treated seed. The addition of an insecticide seed treatment also resulted in higher yields when both herbicides were applied compared to the fungicide-only seed treatment receiving the same herbicide treatments. In 2014, an overall decrease in injury from both herbicides was observed when rice seed was treated with CruiserMaxx Rice compared to receiving a fungicide-only seed treatment. Significant yield loss from low rates of glyphosate or imazethapyr was not observed in 2014, with or without a seed treatment. Based on the positive effects observed from the CruiserMaxx Rice seed treatment in reducing injury and maintaining rice yields, the insecticide seed treatment appears to provide some safening to rice against low rates of glyphosate and imazethapyr.