Pollinators risk exposure to insecticide residue when visiting weedy flowers in urban landscapes. Previous research shows that pollinators are routinely exposed to a variety of pesticides, but herbicides have exhibited minimal toxicity and did not contribute to the modeled risk quotients. Herbicides from different modes of action may deter pollinators from visiting turfgrass weeds, but their temporal influence on floral quality and pollinator foraging is unaddressed. Research experiments were conducted at Blacksburg, VA, in 2023 to assess the effect of four herbicides on floral morphology and ultraviolet (UV) reflectance of three different UV floral classes of weeds and associated pollinator foraging visits. Among 1,080 assessments per weed species, honeybees (Apis mellifera), bumble bees (Bombus spp.), solitary bees (Chelostoma florisomne), and flies (Diptera spp.) accounted for 94%, 2%, 3%, and 1%, respectively, of the total pollinator visitations on white clover (Trifolium repens L.) inflorescences; 71%, 2%, 0%, and 27%, respectively, on dandelion (Taraxacum officinale F.H. Wigg.) flowers; and 0%, 0%, 78%, and 22%, respectively, on bulbous buttercup (Ranunculus bulbosus L.) flowers. Pollinator visitation and floral quality were temporarily affected by herbicide application, with some herbicides eliminating food resources, while others transiently impacted floral quality and density. The combination of 2,4-D + dicamba + MCPP and topramezone eliminated pollinator foraging visits, but on differing temporal scales of 3 d for auxins and 14 d for topramezone. Halosulfuron and sulfentrazone transiently suppressed floral quality and density, with varying degrees of deterrence on pollinators depending on the weed species. All evaluated herbicides reduced radiometric UV reflectance of T. officinale petal apices, but only synthetic auxin and topramezone reduced digitally assessed floral UV-reflecting area. Petal UV reflectance appears to contribute but not solely influence pollinator foraging behavior. UV-absorbing and UV-reflecting flowers differed in UV-reflectance response to herbicides, but pollinators were similarly deterred. Results suggest that herbicides may offer a variety of management solutions to pollinator deterrence in areas slated for insecticide treatment, including long-term or transient deterrence with potential food-resource preservation.

A field experiment was conducted in 2019 and 2020 that included six site-years and four locations in Arkansas to determine the optimal sequence and timing of dicamba and glufosinate applications when applied alone, sequentially, or in combination to control Palmer amaranth by size: labeled (<10 cm height) and non-labeled (13 to 25 cm height). Single applications of dicamba, glufosinate, and dicamba plus glufosinate (not labeled) resulted in less than 80% Palmer amaranth control, regardless of weed size. The mixture of dicamba plus glufosinate was antagonistic for Palmer amaranth control and percent mortality. Sequential applications, averaged over all time intervals and herbicides, improved the percentage of Palmer amaranth control 11 to 17 percentage points over a single application, regardless of weed size at application 28 d after final application (DAFA). Palmer amaranth control with glufosinate followed by (fb) glufosinate and dicamba fb dicamba, pending weed size, were optimized at intervals of 7 d, and 14 to 21 d, respectively. Because single site of action (SOA) postemergence herbicide systems increase the likelihood of the development of resistant biotypes and are not a best management practice (BMP) in that regard; sequential applications involving both dicamba and glufosinate were more effective. Furthermore, the sequence of application mattered with a preference for applying dicamba first. Dicamba fb glufosinate at a 14-d interval was profit-maximizing and the only herbicide treatment that resulted in 100% weed control when size was <10 cm. For larger weed sizes, economic analysis revealed that dicamba fb dicamba performed better than dicamba fb glufosinate when no penalty was assigned for using a single SOA. This resulted in greater yield loss risk and soil weed seed bank in comparison to timelier weed control with the smaller weed size. Hence, timely weed control and two SOAs to control Palmer amaranth are recommended as BMPs that reduce producer risk.

This paper analyzes public willingness to support farmer adoption of best management practices in Oklahoma’s Fort Cobb Watershed, a multiuse area for agriculture, residential water provision, and recreation. The study uses Oklahoma’s Meso-Scale Integrated Sociogeographic Network survey to conduct a contingent valuation analysis of a hypothetical, one-time tax that would support farmer adoption of pasture and riparian buffer management practices. Respondent heterogeneity is modeled using beta-binomial regression. Public support for the hypothetical program is stronger for the tandem implementation of riparian buffer establishment and pasture expansion (willingness to pay [WTP] = $290) and riparian buffer establishment (WTP = $317).

Yield losses due to weeds are a major threat to wheat production and economic well-being of farmers in the United States and Canada. The objective of this Weed Science Society of America (WSSA) Weed Loss Committee report is to provide estimates of wheat yield and economic losses due to weeds. Weed scientists provided both weedy (best management practices but no weed control practices) and weed-free (best management practices providing >90% weed control) average yield from replicated research trials in both winter and spring wheat from 2007 to 2017. Winter wheat yield loss estimates ranged from 2.9% to 34.4%, with a weighted average (by production) of 25.6% for the United States, 2.9% for Canada, and 23.4% combined. Based on these yield loss estimates and total production, the potential winter wheat loss due to weeds is 10.5, 0.09, and 10.5 billion kg with a potential loss in value of US$2.19, US$0.19, and US$2.19 billion for the United States, Canada, and combined, respectively. Spring wheat yield loss estimates ranged from 7.9% to 47.0%, with a weighted average (by production) of 33.2% for the United States, 8.0% for Canada, and 19.5% combined. Based on this yield loss estimate and total production, the potential spring wheat loss is 4.8, 1.6, and 6.6 billion kg with a potential loss in value of US$1.14, US$0.37, and US$1.39 billion for the United States, Canada, and combined, respectively. Yield loss in this analysis is greater than some previous estimates, likely indicating an increasing threat from weeds. Climate is affecting yield loss in winter wheat in the Pacific Northwest, with percent yield loss being highest in wheat-fallow systems that receive less than 30 cm of annual precipitation. Continued investment in weed science research for wheat is critical for continued yield protection.

This paper investigates cost-share program attributes that would affect producers' willingness to enroll in a cost-share program to fund the adoption of best management practices to improve water quality and decrease water use. Through a survey administered to Florida agricultural producers, we conducted choice experiments to assess farmers’ preferences for cost-share programs using five attributes: contracting agency, length of contract, annual verification process, costs included, and percent of costs covered. Results suggest that producers prefer cost-share programs with shorter contract lengths, self-monitoring, and administration by agricultural (as opposed to environmental) agencies. Our findings suggest the importance of an existing trust between the local communities and the contracting agencies for higher enrollment rates in cost –share programs. Our results can inform policymakers on ways to increase enrollment rates that move towards long-term environmental goals.

Kochia [Bassia scoparia (L.) A. J. Scott] is a problematic weed species across the Great Plains, as it is spreading fast and has developed herbicide-resistant biotypes. It is imperative to understand key life-history stages that promote population expansion of B. scoparia and control strategies that would provide effective control of these key stages, thereby reducing population growth. Diversifying weed control strategies has been widely recommended for the management of herbicide-resistant weeds. Therefore, the objectives of this study were to develop a simulation model to assess the population dynamics of B. scoparia and to evaluate the effectiveness of diverse weed control strategies on long-term growth rates of B. scoparia populations. The model assumed the existence of a glyphosate-resistant (GR) biotype in the B. scoparia population, but at a very low proportion in a crop rotation that included glyphosate-tolerant corn (Zea mays L.) and soybean [Glycine max (L.) Merr.]. The parameter estimates used in the model were obtained from various ecological and management studies on B. scoparia. Model simulations indicated that seedling recruitment and survival to seed production were more important than seedbank persistence for B. scoparia population growth rate. Results showed that a diversified management program, including glyphosate, could provide excellent control of B. scoparia populations and potentially eliminate already evolved GR B. scoparia biotypes within a given location. The most successful scenario was a diverse control strategy that included one or two preplant tillage operations followed by preplant or PRE application of herbicides with residual activities and POST application of glyphosate; this strategy reduced seedling recruitment, survival, and seed production during the growing season, with tremendous negative impacts on long-term population growth and resistance risk in B. scoparia.

Distributed models and a good knowledge of the catchment studied are required to assess mitigation measures for nitrogen (N) pollution. A set of alternative scenarios (change of crop management practices and different strategies of landscape management, especially different sizes and distribution of set-aside areas) were simulated with a fully distributed model in a small agricultural catchment. The results show that current practices are close to complying with current regulations, which results in a limited effect of the implementation of best crop management practices. The location of set-aside zones is more important than their size in decreasing nitrate fluxes in stream water. The most efficient location is the lower parts of hillslopes, combining the dilution effect due to the decrease of N input per unit of land and the interception of nitrate transferred by sub-surface flows. The main process responsible for the interception effect is probably uptake by grassland and retention in soils since the denitrification load tends to decrease proportionally to N input and, for the scenarios considered, is lower in the interception scenarios than in the corresponding dilution zones.

Due to depressed corn and soybean prices over the last few years in the United States, growers in Nebraska are showing interest in no-tillage (hereafter referred to as no-till) conventional (non–genetically engineered [non-GE]) soybean production. Due to the increasing number of herbicide-resistant weeds in the United States, weed control in no-till non-GE soybean using POST herbicides is a challenge. The objectives of this study were to compare PRE-only, PRE followed by (fb) POST, and PRE fb POST with residual (POST-WR) herbicide programs for Palmer amaranth and velvetleaf control and soybean injury and yield, as well as to estimate the gross profit margins and benefit–cost ratio of herbicide programs. A field experiment was conducted in 2016 and 2017 at Clay Center, NE. The PRE herbicides tested in this study resulted in ≥95% Palmer amaranth and velvetleaf control at 28 d after PRE (DAPRE). Averaged across the programs, the PRE-only program controlled Palmer amaranth 66%, whereas 86% and 97% control was obtained with the PRE fb POST and PRE fb POST-WR programs, respectively, at 28 d after POST (DAPOST). At 28 DAPOST, the PRE fb POST herbicide programs controlled velvetleaf 94%, whereas the PRE-only program resulted in 85% control. Mixing soil-residual herbicides with foliar-active POST programs did not improve velvetleaf control. Averaged across herbicide programs, PRE fb POST programs increased soybean yield by 10% and 41% in 2016 and 2017, respectively, over the PRE-only programs. Moreover, PRE fb POST-WR programs produced 7% and 40% higher soybean yield in 2016 and 2017, respectively, compared with the PRE fb POST programs. The gross profit margin (US$1,184.3 ha−1) was highest under flumioxazin/pyroxasulfone (PRE) fb fluthiacet-methyl plus S-metolachlor/fomesafen (POST-WR) treatment; however, the benefit–cost ratio was highest (6.1) with the PRE-only program of flumioxazin/chlorimuron-ethyl.

Strategies to prevent chemical contamination of groundwater will be more effective and cost less than cleaning up groundwater. Advances in weed control technologies have improved timing of herbicide applications, have reduced application rates from kg/ha to g/ha, and have distributed herbicides better within the weed-crop complex. These technologies include microbial pesticides, controlled-release formulations, herbicide chemistry, improved integrated weed management systems, and bioeconomic weed-crop models that reduce herbicide use. These new technologies should reduce the quantity of herbicides used by farmers and lessen the chances of groundwater contamination.

Crop losses from weed interference have a significant effect on net returns for producers. Herein, potential corn yield loss because of weed interference across the primary corn-producing regions of the United States and Canada are documented. Yield-loss estimates were determined from comparative, quantitative observations of corn yields between nontreated and treatments providing greater than 95% weed control in studies conducted from 2007 to 2013. Researchers from each state and province provided data from replicated, small-plot studies from at least 3 and up to 10 individual comparisons per year, which were then averaged within a year, and then averaged over the seven years. The resulting percent yield-loss values were used to determine potential total corn yield loss in t ha−1 and bu acre−1 based on average corn yield for each state or province, as well as corn commodity price for each year as summarized by USDA-NASS (2014) and Statistics Canada (2015). Averaged across the seven years, weed interference in corn in the United States and Canada caused an average of 50% yield loss, which equates to a loss of 148 million tonnes of corn valued at over U.S.$26.7 billion annually.

Feral rye, commonly referred to as cereal, winter, common, or volunteer rye, is an important weed in winter wheat production in many parts of the United States and the world. Feral rye reduces net profits in the United States by more than $27 million due to lower grain yields, increased dockage, and reduced land values. To date, limited research has been conducted on components that make feral rye a problem in various cropping systems. Herbicide-tolerant wheat technology can be used to manage feral rye, but current efficacy levels are not adequate for high feral rye densities. In addition, the long-term effects that individual management strategies may have on feral rye populations are unknown. This review addresses the physical, environmental, and genetic characteristics of Secale cereale. Current economic impact, management, and research data gaps are also discussed.

Field experiments were conducted during 2003 and 2004 to compare the effectiveness of KIH-485 and S-metolachlor for PRE weed control in no-tillage and conventional-tillage corn. Longspine sandbur control increased as KIH-485 or S-metolachlor rates increased in conventional-tillage corn, but control did not exceed 75% when averaged over experiments. Both herbicides controlled at least 87% of green foxtail with the exception of no-tillage corn in 2004, when KIH-485 was more effective than S-metolachlor at lower rates. Palmer amaranth control ranged from 85 to 100% in 2003 and 80 to 100% in 2004, with the exception of only 57 to 76% control at the lowest two S-metolachlor rates in 2004. Puncturevine control exceeded 94% with all treatments in 2003. In 2004, KIH-485 controlled 86 to 96% of the puncturevine, whereas S-metolachlor controlled only 70 to 81%. Mixtures of atrazine with KIH-485 or S-metolachlor generally provided the most effective control of broadleaf weeds studied.

Understanding motivating factors for taking soil conservation measures is seen as key to improving on-farm implementation. However, to date only few on-farm conservation measures have been investigated. The objective of this paper is to investigate the influence of farmers’ subjective beliefs on their intention to apply and actual implementation of cover cropping, with the region of Brandenburg (Germany) as a case. An additional objective was to investigate how these insights can contribute to increase farm level implementation of soil conservation measures. Theory of planned behavior provides an approach to understand human behavior by analyzing farmers’ subjective beliefs. Our results, based on a survey of 96 farmers, show that attitudes (ATTs) and perceived difficulty significantly explain variations in intention to apply cover cropping, with ATTs being generally very positive. We discuss that, in this case, the most effective way to increase on-farm implementation is to decrease the farmers’ perception of difficulty. This can be achieved by providing information to farmers on how to overcome barriers to implementation of conservation measures. In-depth insights into belief structures reveal what kind of information is most useful in the case of cover cropping.

Conceptual weaknesses in the use of costs of average abatement as a measure of the cost effectiveness of agricultural nonpoint pollution control are examined. A probabilistic alternative is developed. The focus is on methods for evaluating whole-farm pollution control plans rather than individual practices. As a consequence, the analysis is presented in a chance-constrained activity analysis framework because activity analysis procedures are a practical and well developed device for screening farm plans. Reliability of control is shown to be as important as reduction targets in designing farm plans for pollution control. Furthermore, broad-axe prescriptions of technology in the form of Best Management Practices may perform poorly with respect to cost effectiveness.

A logistic regression procedure was used to assess the impact of socioeconomic attributes on the best management practices (BMPs) adoption decision by Louisiana dairy farmers relative to cost-share and fixed incentive payments. Analysis of the steps in the BMP adoption decision process indicated visits between producers and the U.S. Department of Agriculture–Natural Resource Conservation Service significantly increase likelihood of BMP adoption. Producer willingness-to-pay results indicate that marginal increases in dairy BMP adoption and associated improvement in environmental quality require increased technical and financial assistance.

This study investigates the determinants affecting producers' adoption of some Best Management Practices (BMPs). Priors about the signs of certain variables are explicitly accounted for by testing for inequality restrictions through importance sampling. Education, gender, age, and on-farm residence are found to have significant effects on the adoption of some BMPs. Farms with larger animal production are more apt to implement manure management practices, crop rotation, and riparian buffer strips. Also, farms with larger cultivated acres are more inclined to implement herbicide control practices, crop rotation, and riparian buffer strips. Belonging to an agro-environment club has a positive impact for most BMPs.

The oil palm industry is blamed for the demise of iconic species such as the orang-utan Pongo pygmaeus in Borneo but production of, and demand for, this commodity continue to expand. Therefore, a better understanding of how the orang-utan is adapting to human-transformed environments is crucial for conserving the species. Results from a combination of repeated ground transects, aerial presence/absence surveys, and interviews of workers in mature plantations of the lower Kinabatangan River floodplain (eastern Sabah) provide an overall picture of the current status of orang-utans in an established agro-industrial oil palm landscape. Our results show that orang-utans disperse into mature plantations, use oil palm trees for nesting, and feed on mature fruits. Most oil palm workers report orang-utans of all age–sex classes within the estates but fail to report any negative effect of the animals on productivity of mature palms ≥5 years. Our surveys also show that orang-utan presence in the mature oil palm landscape is correlated with proximity to natural forest patches. These results suggest that forest patches, even when small, fragmented and degraded, are required to sustain the species in human-transformed landscapes. Homogenous oil palm plantations are incompatible with viable populations of orang-utans. The cessation of further forest conversion to agriculture and the enforcement of better management practices are needed to reduce the threat of oil palm development to orang-utan survival.

To establish recommendations for wetland management that promote wildlife diversity in Mediterranean habitats we examined the factors that determine feeding habitat selection by the black stork Ciconia nigra in ponds. The black stork is considered an umbrella species because it is threatened, requires large foraging ranges in priority areas, is selective in its choice of diet and nesting sites, and inhabits a characteristic biological community with endemic and threatened taxa. Eighty-five ponds were monitored in central and western Spain to detect the stork feeding. At the same time, pond variables that could affect black stork feeding preferences were periodically evaluated. Generalized linear mixed models were used to analyse principal components obtained from groups of factors related to structural, location and ecological conditions. The black stork selects ponds distant from roads, with a large surface area, high water level, shallow shores, low turbidity, few traces of wild ungulates on the shores, a high diversity of fish and amphibian species, and a vegetated perimeter, in flat and open areas. Potential factors affecting feeding behaviour are discussed. We suggest measures for pond construction and management that could favour this species in particular and biodiversity in general in the Mediterranean environment.

In Thailand, horticultural practices are a significant source of non-point source (NPS) pollution, and the government is considering best management practices (BMPs) as control measures for reducing agricultural NPS pollution to water. A prevailing assumption that farmers’ reactions to regulations will be homogenous is not based on underlying insights into attitudinal positions that may explain alternative behavioural responses. This paper uses Q-methodology to identify attitudinal discourses relating to BMP uptake. The approach combines the strengths of qualitative and quantitative research in order to explore subjectivity. The study is conducted with citrus growers in the Ping river basin, where farmers are facing increasing competition from alternative water uses. Four ‘discourses’ or viewpoints are identified, namely conservationist, traditionalist, disinterested and risk-averse. The different attitudes of these four groups are likely to be associated with distinctive behavioural reactions to the adoption of alternative policy instruments for pollution control. These discourses could usefully inform targeted policies for the control of NPS pollution from agriculture.