Influence of Deer Repellent and Herbicide Combinations on Weed Control and Deer Browsing in Soybean

Field studies were conducted in 1994 and 1995 to examine the effects of soybean [Glycine max (L.) Merr.] row spacing and application rate and timing of four postemergence herbicide tank mixtures on weed control and soybean yield. Weed control and soybean yield were greater in narrow rows (7.5 in.) than wide rows (30 in.). Herbicide tank mixtures applied at 25% of the full recommended rate at an early postemergence timing followed by a second 25% application at a standard postemergence timing (1/4x E Post + 1/4x Post) resulted in weed control and soybean yield equal to that of herbicide tank mixtures applied at the full recommended rate at a standard postemergence timing (lx Post). Three of four tank mixtures in 1994 and two of four in 1995, applied at 50% of the full rate applied at a standard postemergence timing (1/2x Post) resulted in weed control and soybean yield equal to that of 1x Post applications. All tank mixtures applied at 50% of the full rate at an early postemergence timing (1/2x E Post) resulted in poor weed control and low soybean yield. In most cases it was more profitable to plant soybean in narrow rows than wide rows regardless of application rate or timing, based on economic gross margin calculations. Gross margins of tank mixtures applied at 1/4x E Post + 1/4x Post were similar to or greater tban tbe gross margin of the same tank mixture applied at the full rate in 13 of 16 cases. Gross margins of tank mixtures applied at 1/2x Post were similar to or greater than the gross margin of the same tank mixture applied at the full rate in eight of 16 cases.

Field studies were conducted in 2000, 2001, and 2002 at Brownstown, DeKalb, Perry, and Urbana, IL, to evaluate weed control and corn tolerance from postemergence (POST) applications of foramsulfuron in sequential and total-POST herbicide programs. Foramsulfuron applied alone controlled giant foxtail, fall panicum, and redroot pigweed 88, 99, and 99%, respectively, 28 d after treatment (DAT), which was comparable with the standard treatment of nicosulfuron. However, control of common cocklebur, velvetleaf, and common lambsquarters was significantly higher with foramsulfuron compared with nicosulfuron. Sequential herbicide programs of atrazine, S-metolachlor, or isoxaflutole applied preemergence (PRE) followed by a POST application of foramsulfuron provided greater than 85% control of giant foxtail, fall panicum, common cocklebur, velvetleaf, common waterhemp, and redroot pigweed. Of the sequential herbicide treatments, atrazine applied PRE followed by a POST application of foramsulfuron provided the greatest Pennsylvania smartweed control. A PRE application of either atrazine or isoxaflutole was needed before a POST application of foramsulfuron to control common lambsquarters. POST tank mixtures of foramsulfuron with atrazine, dicamba, and dicamba plus diflufenzopyr improved control of Pennsylvania smartweed, common cocklebur, velvetleaf, common lambsquarters, and common waterhemp when compared with foramsulfuron applied alone. The tank mixture of foramsulfuron with mesotrione improved control of all species, except Pennsylvania smartweed, common lambsquarters, and common cocklebur. Foramsulfuron tank mixtures with carfentrazone did not improve control of any weed species to commercial acceptance. Adjuvant selection was important for POST tank mixtures. Control of giant foxtail and fall panicum was reduced when atrazine was tank mixed with foramsulfuron and crop oil concentrate (COC). However, when methylated seed oil (MSO) was added to the atrazine–foramsulfuron tank mixture instead of COC, giant foxtail and fall panicum control were similar to foramsulfuron applied alone.Nomenclature: Atrazine; carfentrazone; dicamba; diflufenzopyr, 2-[1-[[[(3,5-difluorophenyl)amino]carbonyl]hydrazono]ethyl]-3-pyridinecarboxylic acid; foramsulfuron, 2-[[[[(4,6-dimethoxy-2-pyrimidiny)amino]carbonyl]amino]sulfonyl]-4-(formylamino)-N,N-dimethylbenzamide; isoxaflutole; mesotrione; S-metolachlor; common cocklebur, Xanthium strumarium L. #3 XANST; common lambsquarters, Chenopodium album L. # CHEAL; common waterhemp, Amaranthus rudis Sauer. # AMATA; fall panicum, Panicum dichotomiflorum Michx. # PANDI; giant foxtail, Setaria faberi Herm. # SETFA; Pennsylvania smartweed, Polygonum pennsylvanicum L. # POLPY; redroot pigweed, Amaranthus retroflexus L. # AMARE; velvetleaf, Abutilon theophrasti Medicus # ABUTH; corn, Zea mays L.Additional index words: Antagonism, tank mixture, total-POST.Abbreviations: ALS, acetolactate synthase (EC 4.1.3.18); COC, crop oil concentrate; DAT, days after treatment; MSO, methylated seed oil; NIS, nonionic surfactant; POST, postemergence; PRE, preemergence; UAN, urea ammonium nitrate.

Field experiments were conducted in 1999 and 2000 to determine the influence of mesotrione postemergence application rate, application timing, and addition of atrazine on corn injury, weed control, and corn grain yield. Corn injury in the form of leaf bleaching ranged from 0 to 15% at 7 d after treatment (DAT). In general, most of the bleaching injury rapidly dissipated with slight (≤ 8%) to no corn injury observed at 28 DAT. Control of common cocklebur with mesotrione at 14 DAT ranged from 79 to 98% for all treatments over both years. Applying mesotrione at 140 g/ha, at the early postemergence (EPOST) timing, or in combination with atrazine provided the greatest control of common cocklebur at 14 DAT. Application rate of mesotrione was the only factor that was significant in both years for control of common cocklebur later in the season at 56 DAT. Control of ivyleaf morningglory with mesostrione at 14 DAT ranged from 60 to 90% for all treatments in both years. Control of ivyleaf morningglory at 14 DAT was enhanced by the addition of atrazine to mesotrione. Control of ivyleaf morningglory at 56 DAT was greater with mid-postemergence and late postemergence than with EPOST applications, and was generally enhanced by the addition of atrazine. Yellow nutsedge control with mesotrione was inconsistent, ranging from 40 to 87% at 14 DAT for all treatments over both years. The addition of atrazine to mesotrione increased yellow nutsedge control from 47 to 87% at 14 DAT in 2000. Increasing the rate of mesotrione from 70 to 140 g/ha, as well as the addition of atrazine, improved control of yellow nutsedge at 56 DAT. Corn grain yield was not affected by corn injury or weed control as there were no significant differences in grain yield between herbicide-treated plots and handweeded plots. Nomenclature: Atrazine; mesotrione; common cocklebur, Xanthium strumarium L. #3 XANST; ivyleaf morningglory, Ipomoea hederacea L. Jacq. # IPOHE; yellow nutsedge, Cyperus esculentus L. # CYPES; corn Zea mays L. ‘DK 592SR’, ‘DK 683SR’. Abbreviations: COC, crop-oil concentrate; DAT, days after treatment; EPOST, early postemergence; MPOST, mid-postemergence; LPOST, late postemergence; PRE, preemergence; UAN, 28% urea ammonium nitrate.

Field studies were conducted in 1994 and 1995 in central and southern Illinois to compare several total postemergence weed control programs in soybean [ Glycine max (L.) Merr.]. Herbicide programs evaluated were imazethapyr (an acetolactate synthase (ALS] inhibiting herbicide) applied alone or in combination with lactofen and two non‐ALS herbicide programs consisting of combinations of bentazon, acifluorfen, and sethoxydim and combinations of fomesafen, fluazifop, and fenoxyprop. These treatments were applied early postemergence (EPOST, V‐1 soybean—first trifoliate) and postemergence (POST, V‐2 soybean—second trifoliate). Non‐ALS herbicide programs generally provide more effective weed control POST, while weed control with imazethapyr tended to be greater EPOST. Non‐ALS herbicide programs applied POST provided weed control levels that were equal to imazethapyr in three out of four experiments. In 1994 at Brownstown, broadleaf weed control was poor with non‐ALS herbicide programs when weed growth stages were larger and environmental conditions more extreme than other experiments. Adding lactofen to imazethapyr increased broadleaf weed control in some instances but decreased giant foxtail ( Setaria faberii L.) control. Imazethapyr plus lactofen tended to produce the greatest degree of soybean injury. Research Question Imaiethapyr herbicide is applied primarily postemergence for weed control in soybean and is effective in controlling a broad spectrum of grass and broadleaf weeds. The recent occurrence of weed biotypes in the Midwest resistant to acetolactate synthase (ALS) inhibiting herbicides may cause growers to use alternative, non‐ALS herbicides for weed control. The research reported in this paper was designed to compare two non‐ALS total postemergence herbicide programs to imazethapyr applied alone or in combination with lactofen applied EPOST (early post emergence) and POST (postemergence) for overall weed control and soybean tolerance. Literature Summary Total postemergence herbicide programs for weed control in soybean are widely used throughout the Midwest. Imazethapyr, which controls a broad spectrum of grass and broadleaf weeds, is used on approximately 40 to 50% of the soybean acres in the Midwest. Imazethapyr is generally the only herbicide treatment applied to the majority of these acres. Imazethapyr controls weeds by inhibiting the enzyme ALS. Recently, ALS resistant weed biotypes have been detected throughout the Midwest, which may force growers to switch to non‐ALS herbicide programs or to apply ALS herbicides in combination with non‐ALS herbicides. Decreasing reliance on ALS herbicides or applying herbicides with different modes of action may also help slow the development and spread of ALS resistant weeds. Recently, two non‐ALS total postemergence herbicide programs have been developed using a silicone adjuvant or an internal proprietary adjuvant system. However, information on the performance of these total postemergence systems compared with imazethapyr applied alone or in combination with lactofen (a non‐ALS herbicide) is limited. Study Description Two non‐ALS total postemergence herbicide programs, imazethapyr and imazethapyr plus lactofen were applied EPOST (V‐1 soybean) and POST (V‐2 soybean) to soybean planted in 30‐in. rows. Non‐ALS herbicide programs consisted of bentazon plus aciflourfen (Galaxy), applied at 0.92 lb/acre combined with sethoxydim plus DASH spray adjuvant (Poast Plus) applied at 0.19 lb/acre. A silicone spray adjuvant (Sylguard 309) was added to this treatment at 0.25% v/v. Fomesafen formulated with an internal proprietary adjuvant system (Flexstar), was applied at 0.31 lb/acre combined with fluazifop and fenoxyprop (Fusion) applied at 0.21 lb/acre. Urea ammonium nitrate (UAN, 28%) was added at 2.5% v/v. Imazethapyr was applied alone with nonionic surfactant (NIS) at 0.25% v/v and 2.5% v/v UAN or in combination with 0.13 lb/acre lactofen. NIS was replaced with crop oil concentrate at 0.5% v/v with the lactofen Combination. Soybean injury was visually estimated 10 d after treatment (DAT). Weed control was visually evaluated and soybean height determined 30 d after POST applications. Soybean grain yield was determined at maturity. Applied Questions What is the optimum application timing for the four herbicide treatments? The optimum application timing for the non‐ALS herbicide programs was POST targeting weeds ranging from 3 to 4 in. in height due to the lack of significant soil residual with these treatments. In contrast, the optimum application timing for imazethapyr was EPOST, targeting 1 to 3 in. weeds and most likely due to the significant soil residual with imazethapyr. In some cases, soybean injury with imazethapyr or imazethapyr plus lactofen was lower POST than EPOST. Did non‐ALS herbicide programs applied POST provide equal levels of weed control as compared with imazethapyr or imazethapyr plus lactofen applied EPOST? Non‐ALS herbicide programs applied POST provided weed control levels that were equal to imazethapyr applied EPOST in three out of four experiments. In 1994 at Brownstown, broadleaf weed control was poor with non‐ALS herbicide programs when weed growth stages were larger and environmental conditions more extreme than with other experiments. Adding lactofen to imazethapyr increased broadleaf weed control in some instances but decreased giant foxtail control. Imazethapyr plus lactofen tended to produce the greatest degree of soybean injury. Growers who choose to use imazethapyr and add lactofen to control ALS resistant weed biotypes may have to control giant foxtail with alternative methods or apply lactofen separately from imazethapyr.

Weed control and corn vigor were evaluated to determine the effects of application rate, timing, and other POST herbicides on primisulfuron activity. Corn injury caused by primisulfuron was very low. Weed control varied with species and stage of growth. Primisulfuron showed high activity on emerged johnsongrass, particularly with early postemergence (EP) and mid postemergence (MP) applications. However, these treatments did not provide full season control of this species due to regrowth from rhizomes and continuous germination of new seeds. Primisulfuron controlled giant foxtail with the EP timing (< 5 cm weed height), but not with MP and late postemergence (LP) applications. Common lambsquarters and redroot pigweed control was most effective with EP applications. Primisulfuron in combination with cyanazine, atrazine, cyanazine plus tridiphane, atrazine plus tridiphane, bentazon, 2,4-D, dicamba, or paraquat controlled common lambsquarters and redroot pigweed better than primisulfuron applied alone. Johnsongrass control decreased when primisulfuron was combined with paraquat or 2,4-D and giant foxtail control decreased when primisulfuron was combined with 2,4-D or dicamba.

Understanding how weed and disease management strategies may be implemented in combination is important for improving pest management strategies in peanut (Arachis hypogaea L) production. In greenhouse and field studies, tank mixtures of paraquat and other herbicides, with the fungicide chlorothalonil (tetrachloroisophthalonitrile), were evaluated for their effect on weed control and peanut injury, defoliation due to leafspot diseases (Cercospora arachidicola and Cercosporidium personatum), and yield of peanut. In the greenhouse studies, the bipyridylium herbicide, paraquat, was tank-mixed with each of two formulations of the substituted aromatic fungicidal compound, chlorothalonil. Tank mixtures consisted of 0, 0.06, and 0.12 lb a.i.lacre paraquat and each of two chlorothalonil formulations (a liquid and a dry-flowable) at 0, 0.38, 0.75, and 1.12 lb a.i.lacre. Control of smallflower morningglory [Jacquemontia tamnifolia (L.) Griseb.] increased with increasing rate of paraquat application but was not affected with chlorothalonil in the tank mix. Control of Florida beggarweed [Desmodium tortuosum (Sw.) DC.] and injury on peanut increased with increasing rates of both pesticides, especially with paraquat at 0.06 lb/acre. In 2 yr of field studies, peanut injury due to paraquat, paraquat plus bentazon, paraquat plus bentazon plus 2,4-DB, 2,4-DB, or bentazon was not affected by the addition of chlorothalonil to tank mixtures. Three years of field studies on peanut show that end-of-season defoliation and yield, after a season-long schedule of chlorothalonil applications, were not affected when the initial fungicide application was tank-mixed with paraquat-based herbicide systems or 2,4-DB alone, regardless of chlorothalonil formulation. These data suggest that tank mixtures of chlorothalonil and early-season herbicides are compatible for use on peanut.

A field study was conducted in 2015 and 2016 in Stoneville, MS, to evaluate the influence of cytokinin products on soybean injury and weed control when combined with common POST soybean herbicide treatments. Cytokinin treatments included no cytokinin mixture and two formulated cytokinin mixtures (kinetin-1 and kinetin-2) applied at 0.000227 kg ai ha−1. Herbicide treatments were no herbicide, glyphosate at 1.37 kg ae ha−1 alone and in combination with S-metolachlor at 1.42 kg ai ha−1 or fomesafen 0.395 kg ai ha−1. The addition of cytokinin treatments had no impact on soybean injury, plant height, or yield. Glyphosate plus fomesafen provided the greatest level of Palmer amaranth control, between 84 and 67%., 7 days and 28 days after treatment, respectively. Barnyardgrass control with glyphosate plus fomesafen was antagonized by one of two cytokinin products. To prevent possible reductions in herbicide efficacy, tank mixtures with cytokinin products should not be applied to soybean in POST herbicide applications.

The efficacy of reduced rates of metolachlor plus cyanazine for weed control in sweet corn was evaluated over a 2-yr period. Early postemergence (POST) and POST herbicide applications at reduced rates gave control of broadleaf weeds comparable to control at the 1 × rate, except for the early POST application at the ¼ × rate in 1993. Preplant incorporated (PPI) and preemergence (PRE) herbicide applications at reduced rates gave poor broadleaf weed control, except for the PRE application at the ½ × rate in 1993. Early POST applications at the ¼ × rate resulted in significantly reduced grass control in 1994, while POST applications at the ¼ × rate gave significantly reduced grass control both years. Generally, POST applications controlled broadleaf weeds better than early POST applications, while grass control with early POST applications was superior to POST applications at reduced rates. Preemergence and PPI applications at reduced rates gave poor broadleaf weed control but satisfactory grass control. Preplant incorporated applications at reduced rates resulted in reduced yield both years, while PRE applications at reduced rates reduced yield only in 1994. Early POST and POST applications at reduced rates did not affect sweet corn yield. The addition of adjuvants to the ¼ × application rate had no effect on weed control or yield.

Field experiments were conducted at four locations (Larissa, Halkidona, Thessaloniki, and Halastra) in Greece to evaluate weed and cotton response to various pyrithiobac rates applied preplant incorporated (PPI), preemergence (PRE), or postemergence (POST). Pyrithiobac applied PPI or PRE at 0.068, 0.102, or 0.136 kg ai/ha controlled black nightshade, pigweeds, and common purslane at Larissa. However, pyrithiobac applied PRE at Thessaloniki and Halkidona was more effective against black nightshade and pigweeds than pyrithiobac applied PPI. Pyrithiobac applied PPI or PRE at 0.068 or 0.102 kg/ha did not control common lambsquarters at Thessaloniki. Weed control with trifluralin plus fluometuron applied PPI and alachlor plus fluometuron applied PRE at Larissa was slightly lower than that obtained with pyrithiobac. At Halkidona, trifluralin plus fluometuron applied PPI and alachlor plus fluometuron applied PRE provided weed control similar to that obtained with pyrithiobac. But at Thessaloniki, these treatments provided better weed control than pyrithiobac. Furthermore, pyrithiobac applied early postemergence (EPOST), midpostemergence, or in sequential systems controlled black nightshade and pigweeds, but it resulted in fair to good control of common purslane, velvetleaf, and common cocklebur. None of the POST treatments controlled common lambsquarters. Fluometuron EPOST controlled black nightshade, common lambsquarters, and common purslane ≥70, 86, and 67%, respectively. Fluometuron EPOST did not control pigweeds, velvetleaf, and common cocklebur. Cotton treated with pyrithiobac, regardless of method of application, yielded similar to the weed-free control. Cotton treated with pyrithiobac PPI at the highest rate (0.136 kg/ ha) yielded less at Halkidona, although adverse effects after its application were not visually apparent. Yield of cotton treated with herbicides was similar, with no difference among treatments.Nomenclature: Alachlor; fluometuron; pyrithiobac; trifluralin; black nightshade, Solanum nigrum L. #3 SOLNI; common cocklebur, Xanthium strumarium L. # XANST; common lambsquarters, Chenopodium album L. # CHEAL; common purslane, Portulaca oleracea L. # POROL; prostrate pigweed, Amaranthus blitoides S. Wats AMABL; redroot pigweed, Amaranthus retroflexus L. # AMARE; velvetleaf, Abutilon theophrasti Medicus # ABUTH; cotton, Gossypium hirsutum L. ‘Stoneville 474’, ‘Hazera Vered’, ‘Deltapine 20’, ‘Deltapine 50’, ‘Stoneville Bravo’.Additional index words: Application timing, cotton herbicide, crop injury, residual activity.Abbreviations: EPOST, early postemergence; MPOST, midpostemergence; MSMA, monosodium salt of methylarsonic acid; POST, postemergence; PPI, preplant incorporated; PRE, preemergence; WAP, weeks after planting; WAT, weeks after treatment.

Field studies were conducted at three locations in 1993 and 1994 to evaluate weed control and crop response to combinations of glyphosate, metolachlor, 0.5 X and 1 X label rates of chlorimuron plus metribuzin applied prior to planting (PP), and 0.5 X and 1 X label rates of imazethapyr applied early postemergence (EPOST) or postemergence (POST) in no-till narrow-row soybean production. Giant foxtail densities were reduced with sequential PP followed by (fb) EPOST or POST treatments. Large crabgrass was reduced equivalently with all herbicide combinations involving chlorimuron plus metribuzin PP fb imazethapyr. Common cocklebur control was variable but was usually greater with treatments that included imazethapyr. Ivyleaf morningglory densities were not reduced with any herbicide combinations. Sequential PP fb EPOST or POST treatments tended to provide slightly better weed suppression than PP-only treatments, but the difference was rarely significant. Soybean yields with treatments utilizing 0.5 X rates were usually equal to 1 X rates.

Manual weeding, maize-cowpea intercropping, pre-emergence (PRE) and early post-emergence (EPOST) herbicide applications comprised ten weed control practices evaluated in the 2015-16 cropping season on weed species structure and maize (Zea mays L.) yield in the Middleveld and Highveld of Swaziland. The herbicides used were Harness (acetochlor) and Dual Gold (S-metolachlor) as pre-emergence applications and Micro-Tech (alachlor) and Callisto (mesotrione) as early post-emergence applications. PRE and EPOST herbicides were used as once-off or combined applications besides manual weeding or intercropping practices. Results indicated that the combination of PRE and EPOST herbicides reduced both species richness (number) and evenness (dominance) but weed species composition (types) were not distinguished amongst treatments. Manual weeding in combination with PRE herbicides or maize-cowpea intercropping resulted in significantly lower weed density and biomass as compared to singular or combinations of PRE or EPOST herbicides in both locations. The effects of weed control practices on grain yield of maize were not significantly distinguished among weed control practices between the two sites. The study reaffirmed that herbicides may need to be supplemented with other weed control strategies to obtain acceptable weed control. Key words: Herbicides, maize, Shannon-Wiener diversity index, Simpson’s dominance index, Steinhaus coefficient index, weeds.

Metribuzin [4‐amino‐6‐tert‐butyl‐3‐(methylthlo)‐as‐triazin‐5)4H) one] controls several species of annual broadleaf weeds in soybeans [Glycine max (L.) Merr.]; however, inconsistent weed control and excessive crop injury sometimes result from the use of metribuzin. To determine the extent to which rate of application, rainfall, and depth of incorporation influence weed control and crop injury with metribuzin, microplot and large plot field experiments were conducted in 1973 and 1974. In microplot studies, metribuzin provided 67 to 100% control of comon ragweed (Ambrosia artemisiifolia L.), prickly sida (Sida spinosa L.), velvetleaf (Abutilon theophrasti Medic.), and jimsonweed (Datura stramonium L.). Degree of weed control increased with a corresponding increase in herbicide rate from 0.56 to 0.84 kg/ha. Increased control of these species (and slightly greater soybean injury) resulted from increasing depth of soil‐incorporation from 0 to 7.6 cm. Control of common cocklebur (Xanthium pensylvanicum Wallr.) and ivyleaf morningglory [Ipomoea hederacea (L.) Jacq.] was only 35 to 75% but control did improve with increased herbicide rate and depth of incorporation. Abundant rainfall within 10 days after treatment resulted in 88 to 99% control of velvetleaf and 85 to 95% control of jimsonweed. However, control of these two weeds was poor under limited rainfall, unless metribuzin was incorporated to a depth of at least 5.1 cm. Ivyleaf morningglory was not controlled well with metribuzin in the microplots (12 to 62%) regardless of rate, rainfall, or depth of incorporation. In the large plot studies, metribuzin, under moderate‐to‐abundant rainfall conditions, controlled several annual broadleaf weed species, whether applied preemergence to the soil surface or used as a preplant soil‐incorporated treatment. Metribuzin injured soybeans and caused significant yield reduction when soil‐incorporated at 1.12 kg/ha.

Field studies were conducted to evaluate common cocklebur control in soybean with imazaquin applied preplant incorporated (PPI), preemergence (PRE), and postemergence (POST) at rates ranging from 24 to 140 g ai ha-1. With logistic regression analysis, predictions of common cocklebur control with imazaquin at 140 g ha-1ranged from 92 to 95% (PPI), 87 and 92% (PRE), and 88 to 98% (POST) when rainfall was received for activation of PRE treatments and when weeds were not moisture stressed at time of POST application. When imazaquin was reduced to 70 g ha-1under the same conditions, weed control was no higher than 88% PPI and 78% PRE. For all locations and years, common cocklebur control ranged from 79 to 91% for imazaquin POST at 24 g ha-1. Soybean yield was positively correlated with common cocklebur control (r = 0.66, P < 0.05).

White‐tailed deer ( Odocoileus virginianus Zimmermann) and insect pests negatively affect soybean production; however, little is known about how these herbivores potentially interact to affect soybean yield. Previous studies have shown deer browse on non‐crop plants affects insect density and insect‐mediated leaf damage, which together reduce plant reproductive output. In soybeans, reproductive output is influenced by direct and indirect interactions of different herbivores. Here, we quantified indirect interactions between two groups of herbivores (mammals and insects) and their effects on soybean growth and yield. We examined responses of insect pest communities along a gradient of deer herbivory (29% to 49% browsed stems) in soybean monocultures. Structural equation models showed that deer browse had direct negative effects on soybean plant height and yield. Deer browse indirectly decreased insect‐mediated leaf damage by reducing plant height. Deer browse also indirectly increased pest insect abundance through reductions in plant height. Similarly, deer herbivory had an indirect positive effect on leaf carbon: nitrogen ratios through changes in plant height, thereby decreasing leaf nutrition. These results suggest that pest insect abundance may be greater on soybean plants in areas of higher deer browse, but deer browse may reduce insect herbivory through reduced leaf nutrition.

The southern United States produces 90% of the nation’s cotton, and the Texas High Plains is the largest contiguous cotton producing region. Since 2011, glyphosate-resistant Palmer amaranth has complicated cotton production, and alternatives to glyphosate are needed. Integrating soil residual herbicides into a weed management program is a crucial step to control glyphosate resistant weeds before emergence. The recent development of p-hydroxyphenylpyruvate dioxygenase (HPPD)-resistant cotton by BASF Corporation may allow growers to use isoxaflutole in future weed management programs. In 2019 and 2020, field experiments were conducted in New Deal, Lubbock, and Halfway, Texas, to evaluate HPPD-resistant cotton response to isoxaflutole applied preemergence (PRE) or early postemergence (EPOST) and to determine the efficacy of isoxaflutole when used as part of a season-long weed management program. At the New Deal location, cotton response was observed following the EPOST application, but it never exceeded 10%. Cotton response was greatest following the PRE application in Lubbock in 2019 but did not exceed 14%. In 2020 in Lubbock, cotton was replanted due to severe weather. There was <1% cotton response following the PRE application, and maximum cotton response observed was 9% following EPOST and mid-postemergence (MPOST) applications. Cotton lint yields were not different from those of the nontreated, weed-free control at either location. In non-crop weed control studies in Halfway, all treatments controlled Palmer amaranth ≥94% 21 d after the EPOST application. Twenty-one days after the MPOST treatment, systems with isoxaflutole applied EPOST controlled Palmer amaranth by 88% to 93%, while systems with isoxaflutole PRE controlled Palmer amaranth by 94% to 98%. End-of-season Palmer amaranth control was lowest in the system without isoxaflutole (88%) and when isoxaflutole was used EPOST (88% to 91%). These studies suggest that the use of isoxaflutole in cotton weed management systems may improve season-long control of several troublesome weeds with no adverse effects on cotton yield and quality.