About 25 ppm of 4-amino-3,5,6-trichloropicolinic acid (picloram) usually were detected on grass, primarily buffalograss (Buchloe dactyloides (Nutt.) Engelm.) and blue grama (Bouteloua gracilis Willd. ex HBK Lag ex Griffiths), immediately after application of 0.28 kg/ha picloram + 0.28 kg/ha (2,4,5-trichlorophenoxy)acetic acid (2,4,5-T) in northwest Texas. Less than 1 ppm of picloram usually was detected in grass tissue 30 to 60 days after treatment. At one location, detectable picloram increased in grass tissue from 32 to 60 days after application. Increases of picloram in aerial grass tissue were attributed to root uptake during a flush of vegetative growth. Picloram dissipation from grasses was not affected by irrigation to runoff at 10, 20, or 30 days after application. Detectable picloram was reduced by 93% in herbaceous, broadleaf species by 30 days after application. Treated sand shinnery oak (Quercus havardii Rydb.) leaves at the soil surface caused a slight increase of picloram in surface litter.

In four field experiments, acifluorfen {5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid} applied preemergence at 1.1 kg/ha was not phytotoxic to peas (Pisum sativum L.) and increased the yield of shelled peas by an average of 25% compared to the weedy control. Yields were highest in all four experiments at the 1.1 kg/ha rate and tended to decline at higher rates of application. Growth chamber studies demonstrated that pea tolerance to acifluorfen was not affected by temperatures of 16/10 to 27/21C (light/dark) nor by stimulated rainfall of 0.5 to 5.0 cm. Peas and soybeans [Glycine max (L.) Merr.] were more tolerant of acifluorfen than were snap beans (Phaseolus vulgaris L.) and lima beans (Phaseolus lunatus L.) when acifluorfen was applied preemergence in the greenhouse or in hydroponic nutrient solution.

Legal protection of intellectual property is a requisite to the commercialization of the intellectual property and to the conferring of proper reward to the true owner of the property. Simplistically stated, this situation with regard to intellectual property is no different from the legal protection of a variety of properties, for example, home, land, or automobile. Laws have been established in the various countries of the world that are structured specifically to attain the desired goal of legally protecting property interests. In the intellectual property field, wherein we talk about property such as new inventions, we enter an area of not only protecting the legal rights of the property owner but also insuring the position of the public with respect to the eventual unlimited use of new inventions.

Field research to determine the influence of weed control systems in winter barley on subsequently no-till-planted grain sorghum was conducted from 1985 to 1987 in northwest Georgia. Herbicide treatments applied to fully tillered winter barley included 2,4-D, dicamba, metribuzin, oryzalin, oryzalin plus metribuzin, fluorochloridone, or thiameturon. None of these herbicides affected barley grain yields compared to nontreated plots. Treatments containing oryzalin reduced johnsongrass fresh weights in the subsequently planted grain sorghum. Oryzalin plus metribuzin, in 1 of 2 yr, resulted in higher seed yields of subsequently planted grain sorghum compared to the other treatments except for oryzalin used alone. Treatments containing paraquat plus propazine plus metolachlor applied to grain sorghum provided good weed control when averaged across barley treatments and resulted in the highest grain sorghum yield. No grain sorghum injury from herbicides used in the previous winter barley crop was observed.

After land was plowed in the spring and prepared for planting, yellow nutsedge (Cyperus esculentus L.) was allowed to develop to heights of 10 to 12 and 20 to 25 cm. Either glyphosate [N-(phosphonomethyl)glycine] or paraquat (1,1′-dimethyl-4,4′-bipyridinium ion) was applied to emerged yellow nutsedge and other annual weeds at rates of 0.5, 1, 2, and 4 kg/ha. Half of the plots were double-disked 3 days after herbicide applications, and then all plots were planted with alfalfa (Medicago sativa L. ‘Cayuga’). Disking alone and application of glyphosate or paraquat alone did not satisfactorily control all weeds. However, the combination of a herbicide and disking controlled weeds enough to allow excellent establishment of alfalfa. In the year after establishment, the first cutting yields from the better combination treatments ranged from 3000 to 4400 kg/ha, which is normal for mid- to late-summer plantings in the region. Glyphosate was better than paraquat for control of grass weeds. Paraquat approached glyphosate in effectiveness when a supplemental disking treatment was added. Disking was as effective as the herbicide treatments for control of yellow nutsedge but not for control of broadleaf or annual grass weeds.

The phytotoxicity of postemergence propanil (3′,4′-dichloropropionanilide) to hard red spring (HRS) wheat (Triticum aestivum L.) was determined in the field and controlled environmental chamber. HRS wheat tolerance to propanil was influenced by cultivar, crop growth stage at time of application, and posttreatment temperature. Injury to wheat from propanil was greater at the five- than two-leaf stage of application and at 30- than at 10- or 20-C posttreatment temperatures. ‘Butte’ wheat was the most susceptible HRS wheat cultivar to propanil, with yield reductions ranging from 15 to 40% depending upon year and crop growth stage at application.

Rapid growth of Palmer amaranth (Amaranthus palmeri S. Watson) poses a challenge for timely management of this weed. Dose–response studies were conducted in 2017 and 2018 under field and greenhouse conditions near Garden City and Manhattan, KS, respectively, to evaluate the efficacy of dicamba to control ≤10-, 15-cm, and 30-cm-tall A. palmeri, which mimics three herbicide application timings: on-time application (Day 0) and 1- (Day 1) and 4-d (Day 4) delays. Visual injury rating and reduction in shoot biomass (% of nontreated), and mortality were assessed at 4 wk after treatment using a three- and four-parameter log-logistic model in R. Increasing dicamba doses increased A. palmeri control regardless of plant height in both the field and greenhouse studies. The results suggest that delaying application 1 (15 cm) and 4 d (30 cm) resulted in 2- and 27-fold increases in the effective dose of dicamba on A. palmeri, respectively, under field conditions. However, in the greenhouse, for the same level of A. palmeri control, more than 1- and 2-fold increases in dicamba dose, respectively, were required. Similarly, the effective dose of dicamba required for 50% reduction in A. palmeri shoot biomass (GR50) increased more than 4- and 8-fold or more than 1- and 2-fold when dicamba application was delayed by 1 (15 cm) and 4 d (30 cm), in the field or in the greenhouse, respectively. To understand the basis of increased efficacy of dicamba in controlling early growth stages of A. palmeri, dicamba absorption and translocation studies were conducted. Results indicate a significant reduction in dicamba absorption (7%) and translocation (15%) with increase in A. palmeri height. Therefore, increased absorption and translocation of dicamba results in increased efficacy in improving A. palmeri control at early growth stages.

Palmer amaranth (Amaranthus palmeri S. Watson) is a troublesome weed in several cropping systems in the United States. The evolution of resistance to multiple herbicides is a challenge for the management of this weed. Recently, we reported metabolic resistance to 2,4-D possibly mediated by cytochrome P450 (P450) activity in a six-way-resistant A. palmeri population (KCTR). Plant growth temperature can influence the herbicide efficacy and level of resistance. The effect of temperature on 2,4-D resistance in A. palmeri is unknown. In the present research, we investigated the response of KCTR and a known susceptible (MSS) A. palmeri response to 2,4-D grown under low-temperature (LT, 24/14 C, day/night [d/n]) or high-temperature (HT, 34/24 C, d/n) regimes. When MSS and KCTR plants were 8- to 10-cm tall, they were treated with 0, 140, 280, 560 (field recommended dose), 1,120, and 2,240 g ai ha−1 of 2,4-D. Further, 8- to 10-cm-tall MSS and KCTR plants grown at LT and HT were also treated with [14C]2,4-D to assess the metabolism of 2,4-D at LT and HT. The results of dose–response experiments suggest that KCTR A. palmeri exhibits 23 times more resistance to 2,4-D at HT than MSS. Nonetheless, at LT, the resistance to 2,4-D in KCTR was only 2-fold higher than in MSS. Importantly, there was enhanced metabolism of 2,4-D in both KCTR and MSS A. palmeri at HT compared with LT. Further, treatment with the P450 inhibitor malathion, followed by 2,4-D increased the susceptibility of KCTR at HT. Overall, rapid metabolism of 2,4-D increased KCTR resistance to 2,4-D at HT compared with LT. Therefore, the application of 2,4-D when temperatures are cooler can improve control of 2,4-D–resistant A. palmeri.

Field studies were conducted in 2021 in Kibler and Augusta, AR, to determine the effect of winter cover crops and cultivar selection on weed suppression and sweetpotato [Ipomoea batatas (L.) Lam.] yield. The split-split-plot studies evaluated three cover crops [cereal rye (Secale cereale L.) + crimson clover (Trifolium incarnatum L.)], [winter wheat (Triticum aestivum L.) + crimson clover], and fallow; weeding (with or without); and four sweetpotato cultivars (‘Heartogold’, ‘Bayou-Belle-6’, ‘Beauregard-14’, and ‘Orleans’). Heartogold had the tallest canopy, while Beauregard-14 and Bayou Belle-6 had the longest vines at 5 and 8 wk after sweetpotato transplanting. Sweetpotato canopy was about 20% taller in weedy plots compared with the hand-weeded treatment, and vines were shorter under weed interference. Canopy height and vine length of sweetpotato cultivars were not related to weed biomass suppression. However, vine length was positively correlated to all yield grades (r > 0.5). Weed biomass decreased 1-fold in plots with cover crops compared with bare soil at Augusta. Cover crop biomass was positively correlated with jumbo (r = 0.29), no. 1 (r = 0.33), and total sweetpotato yield (r = 0.34). Jumbo yield was affected the most by weed pressure. On average, sweetpotato total yield was reduced by 80% and 60% with weed interference in Augusta and Kibler, respectively. Bayou Belle-6 was the high-yielding cultivar without weed interference in both locations. Bayou Belle-6 and Heartogold were less affected by weed interference than Beauregard-14 and Orleans.

The U.S. Department of Agriculture–Agricultural Research Service (USDA-ARS) has been a leader in weed science research covering topics ranging from the development and use of integrated weed management (IWM) tactics to basic mechanistic studies, including biotic resistance of desirable plant communities and herbicide resistance. ARS weed scientists have worked in agricultural and natural ecosystems, including agronomic and horticultural crops, pastures, forests, wild lands, aquatic habitats, wetlands, and riparian areas. Through strong partnerships with academia, state agencies, private industry, and numerous federal programs, ARS weed scientists have made contributions to discoveries in the newest fields of robotics and genetics, as well as the traditional and fundamental subjects of weed–crop competition and physiology and integration of weed control tactics and practices. Weed science at ARS is often overshadowed by other research topics; thus, few are aware of the long history of ARS weed science and its important contributions. This review is the result of a symposium held at the Weed Science Society of America’s 62nd Annual Meeting in 2022 that included 10 separate presentations in a virtual Weed Science Webinar Series. The overarching themes of management tactics (IWM, biological control, and automation), basic mechanisms (competition, invasive plant genetics, and herbicide resistance), and ecosystem impacts (invasive plant spread, climate change, conservation, and restoration) represent core ARS weed science research that is dynamic and efficacious and has been a significant component of the agency’s national and international efforts. This review highlights current studies and future directions that exemplify the science and collaborative relationships both within and outside ARS. Given the constraints of weeds and invasive plants on all aspects of food, feed, and fiber systems, there is an acknowledged need to face new challenges, including agriculture and natural resources sustainability, economic resilience and reliability, and societal health and well-being.

Cereal rye (Secale cereale L.) as a cover crop can be an effective nonchemical tool for waterhemp [Amaranthus tuberculatus (Moq.) Sauer] suppression in crop production. Previous studies have evaluated A. tuberculatus suppression by cereal rye as part of weed management programs but have not investigated the underlying mechanism of suppression by the cover crop. This study aimed to investigate the effect of cereal rye biomass on A. tuberculatus emergence and development, and on soil environmental parameters (temperature, moisture, and light transmittance) that are key triggers of A. tuberculatus germination to elucidate the mechanism of suppression by the cover crop. A dose–response study was conducted under field conditions in Brooklyn and Janesville, WI, from 2021 to 2023. Cereal rye biomass from a fall-planted field was harvested at anthesis in the spring and dried to constant weight at 60 C to provide 0.0, 0.6, 1.2, 2.4, 4.8, 7.2, 9.6, and 12.0 Mg ha−1 of dry biomass that was evenly distributed over 1.9 m−2 plots. Increasing cereal rye biomass reduced A. tuberculatus height, biomass, and density. An average ED50 of 5.2 Mg ha−1 of biomass was needed to reduce A. tuberculatus density by 50%. Low levels of biomass (≤2.38 Mg ha−1) augmented A. tuberculatus density due to an increase in soil moisture underneath the mulch compared with bare soil. Cereal rye biomass decreased the amount of sunlight reaching the soil, which resulted in lower mean soil temperature and temperature amplitude throughout the day (9.3 and 2.7 C temperature amplitude at 0 and 12.0 Mg ha−1, respectively). Prevention of A. tuberculatus germination by this thermal effect is likely the main mechanism of A. tuberculatus suppression from the cereal rye cover crop. Our results support biomass from cereal rye cover crop effectively suppressing A. tuberculatus and contributing to the integrated management of A. tuberculatus.

Palmer amaranth (Amaranthus palmeri S. Watson) is a major biotic constraint in agronomic cropping systems in the United States. While crop–weed competition models offer a beneficial tool for understanding and predicting crop yield losses, within these models, certain weed biological characteristics and their responses to the environment are unknown. This limits understanding of weed growth in competition with crops under different irrigation methods and how competition for soil moisture affects crop growth parameters. This research measured the effect of center-pivot irrigation (CPI) and subsurface drip irrigation (SDI) on the actual evapotranspiration (ETa) of A. palmeri grown in maize (Zea mays L.), soybean [Glycine max (L.) Merr.], and fallow subplots. Twelve A. palmeri plants were alternately transplanted 1 m apart in the middle two rows of maize, soybean, and fallow subplots under CPI and SDI in 2019 and 2020 in south-central Nebraska. Maize, soybean, and fallow subplots without A. palmeri were included for comparison. Soil-moisture sensors were installed at 0-0.30, 0.30-0.60, and 0.60-0.90-m soil depths next to or between three A. palmeri and crop plants in each subplot. Soil-moisture data were recorded hourly from the time of A. palmeri transplanting to crop harvest. The results indicate differences in A. palmeri ETa between time of season (early, mid-, and late season) and crop type across 2019 and 2020. Although irrigation type did not affect subplot data, the presence of A. palmeri had an impact on subplot ETa across both years, which can be attributed to the variable relationship between volumetric soil water content (VWC) and ETa throughout the growing season due to advancing phenological stages and management practices. This study provides important and first-established baseline data and information about A. palmeri evapotranspiration and its relation to morphological features for future use in mechanistic crop–weed competition models.

This paper is a review of and a commentary on the published addresses of WSSA presidents from the founding of the Society through 2000. The paper's assumptions are that the presidential remarks will reveal what the Society has emphasized, what its major concerns and goals have been, and how the presidents have addressed what they considered to be important issues. Seven issues have been addressed by many presidents. These include the importance of agricultural production and profit, the necessity of herbicides, weed science and the environment, the regulation of herbicides, the need for education, comparison of weed science and other plant protection disciplines, and the problem of herbicide resistance.

As a representative of the chemical industry, this subject is a rather difficult one to discuss. When one stops a moment to think about the role of the university in herbicidal testing, immediately he realizes that this probably never has been defined and it appears for the most part the administration and research personnel of each university follow the road that is the best of their liking. Far too often, they do not stop and ask themselves whether they really are taking the proper route.

In discussing this topic, one can take the approach that all universities, and some are in this category, are doing an excellent job and compliment everyone that an adequate job is being done. Or one can conclude that the universities should not be doing field evaluations (and please understand this is in the minds of a few university administrators) or the answers to the field problems can be solved in the laboratories; or finally, one can conclude that the universities are not doing a proper job and that considerable improvement must take place. Perhaps I will make some new enemies today (although the Chairman, Dr. Ries, indicated I could take any approach I preferred), but I am of the opinion that our university and experiment station system primarily is not doing a proper job in testing herbicides and that they must take a more active role in the future than they have in the past.

According to Bonner, at least three different oxidase systems may be involved in the final step of the transfer of electrons to oxygen. Each of the terminal oxidases has been shown to occur in many plants and in many relative combinations.

Total alkaloid concentration, percentage water, crude protein, and neutral detergent fiber in velvet lupine (Lupinus leucophyllus Dougl. # LUPLE) were monitored for 3 weeks following application of herbicides registered or soon to be registered for rangeland use. Picloram (4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid), dicamba (3,6-dichloro-2-methoxybenzoic acid), and clopyralid (3,6-dichloro-2-pyridinecarboxylic acid) caused some signs of epinasty but did not kill velvet lupine. Total alkaloid concentration and nutrient quality of velvet lupine leaves treated with these herbicides was not significantly different from untreated plants. Esters of 2,4-D [(2,4-dichlorophenoxy)acetic acid] and 2,4,5-T [(2,4,5-trichlorophenoxy)acetic acid] and triclopyr {[(3,5,6-trichloro-2-pyridinyl)oxy]acetic acid} killed most velvet lupine plants and caused a subsequent decrease in total alkaloid concentration, crude protein, and water content as the plants desiccated. Herbicides that effectively killed velvet lupine decreased alkaloid levels, thus lowering the potential for increased livestock poisoning.

A 3-year field experiment was initiated in 1967 to study the effects of herbicides in combination with the systemic insecticide, O,O-diethyl S-2-[(ethylthio)ethyl] phosphorodithioate (disulfoton) on cotton (Gossypium hirsutum L.). Herbicide treatments of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (diuron), 1,1-dimethyl-3-(α,α,α,-trifluoro-m-tolyl)urea (fluometuron), 3-(hexahydro-4,7-methanoindan-5-yl)-1,1-dimethylurea (norea), 4-(methylsulfonyl)-2,6-dinitro-N,N-dipropylaniline (nitralin), and α,α,α,-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine (trifluralin) did not significantly affect yield of weed-free cotton while disulfoton treatment significantly increased yield over the 3-year period. Yield with disulfoton was negatively correlated with number of thrips (Thripidae sp.). No interaction occurred between herbicides and disulfoton on yield, and only in 1 year was there an effect on stand.