Target‐site and non‐target‐site mechanisms confer multiple herbicide resistance in waterhemp ( <scp> <i>Amaranthus tuberculatus</i> </scp> ) accessions from Wisconsin

Pest Management Science · 2026-03-02

BACKGROUND: A preliminary screening identified a multiple herbicide-resistant waterhemp, Amaranthus tuberculatus (Moq.) Sauer, accession (A101) exhibiting resistance to 2,4-D and atrazine despite no prior exposure to these herbicides. Therefore, our objective was to characterize resistance to 2,4-D, atrazine, glyphosate, fomesafen, and mesotrione in A101, along with two additional multiple herbicide-resistant accessions (A75 and A103). RESULTS: A101 exhibited low to medium levels of resistance to all five herbicides evaluated (ranging from 1.8-fold for mesotrione to 8.5-fold for fomesafen). Both A75 and A103 also had multiple resistance to glyphosate and atrazine, with A75 and A103 additionally resistant to 2,4-D and fomesafen, respectively. Amplification of EPSPS and the P106S substitution accounted for some of the glyphosate resistance, and some of the fomesafen resistance was explained by the G210 deletion in the target enzyme. Moreover, the use of cytochrome P450 monooxygenases (P450s) and glutathione S-transferases (GSTs) inhibitors indicated that non-target-site resistance (NTSR) mechanisms also contribute to at least some of the resistance traits. CONCLUSION: Metabolic resistance to 2,4-D and atrazine suggests that the use of other herbicides may have contributed to the selection of enhanced P450s and GSTs activity in A101 accession. To our knowledge, this is the first report of P450s associated with atrazine resistance in A. tuberculatus globally. A101 is the first confirmed case of A. tuberculatus resistance to hydroxyphenyl pyruvate dioxygenase inhibitors in Wisconsin, exhibiting a low-level resistance likely associated with P450s and GSTs activity. Our results suggest the coexistence of target-site resistance and NTSR mechanisms associated with glyphosate resistance in A101. © 2026 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Laser Weeding Technology: A Precision Approach for Sustainable Weed Management in Vegetable Crops

Outlooks on Pest Management · 2025-10-01 · 1 citations

Synthetic herbicides were first commercialized in the 1940’s and rapidly adopted in agriculture because of their high effectiveness. By 1988, the chemical weed control toolbox had expanded to over 30 sites of action (Heap 2025). The introduction of herbicide‐resistant agronomic crops in the late 1990s simplified weed control and increased reliance on a few broad‐spectrum herbicides across millions of hectares. Many growers still rely on transgenic crops as the foundation of their weed management programs with herbicide‐resistant crops grown on 167 million hectares worldwide in 2019.

Associations among weed communities, management practices, and environmental factors in U.S. snap bean (Phaseolus vulgaris) production

PLoS ONE · 2025-09-23

Weed species that escape control (hereafter called residual weeds) coupled with changing weather patterns are emerging challenges for snap bean processors and growers. Field surveys were conducted to identify associations among crop/weed management practices and environmental factors on snap bean yield and residual weed density. From 2019-2023, a total of 358 snap bean production fields throughout the major U.S. production regions (Northwest, Midwest and Northeast) were surveyed for residual weeds. Field-level information on crop/weed management, soils, and weather also were obtained. To determine associations among management and environmental variables on crop yield and residual weed density, the machine learning algorithm random forest was utilized. The models had 24 and 22 predictor variables for crop yield and residual weed density, respectively, and both were trained on 80% of the data with the remainder used as a test set to determine model accuracy. Both models had pseudo-R2 values of over 0.50 and accuracy over 80%. The models showed that crop yield was higher in the Northwest compared to the Midwest region, while higher average temperatures during early season growth and planting midseason (June-July) predicted greater crop yield compared to other time periods. The use of row cultivation was associated with lower snap bean yield and weed density, suggesting row cultivation had less-than-ideal selectivity between the crop and weed. Moreover, multiple spring tillage operations prior to planting were linked with an increase in weed density, implying that excessive tillage may favor the emergence of residual weeds in snap bean. Over the coming decades, climate change-driven weather variability is likely to influence snap bean production, both directly through crop growth and indirectly through weeds that escape control practices that also are influenced by the weather.

Integrated pest management: state infrastructure status after 50 yr of Federal support (1973 to 2023)

Journal of Integrated Pest Management · 2025-01-01 · 1 citations

Abstract Integrated pest management uses a variety of tools coupled with historical, current, and projected information for economical pest protection of crops and other resources while accounting for risk to humans and the environment. Following the 1972 US Federal IPM Policy, funding for integrated pest management programming has continued for 50+ yr. However, multifaceted changes during this time have significantly affected state-level integrated pest management infrastructure, prompting a comprehensive survey to assess conditions, limitations, and growth potential of US integrated pest management programs. A survey was sent to 50 US states and 3 territories with integrated pest management programs in November 2022. Questions assessed integrated pest management-related staffing, funding, challenges, and other subjects. Information on invasive and emerging pests and barriers to providing integrated pest management to underserved populations was also requested. Results indicated 1,000+ integrated pest management specialists exist across state integrated pest management programs. integrated pest management programs involve diverse networks and stakeholders including university-based, federally funded, and society-based entities. The survey identified a clear need for a robust integrated pest management programmatic network containing trained multidisciplinary integrated pest management specialists to address the challenges caused by a changing climate, invasive species, pest and pesticide resistance, regulatory changes, and technological advances. A strong and collaborative group of integrated pest management specialists must be maintained and strengthened to address pressing and pervasive threats to food security and human health and wellbeing caused by existing, new, and emerging pests. A unified vision and stable support are needed to enhance and empower multistate integrated pest management programs, creating a national system so all can access the information, services, and tools for protection of health, home, and livelihood.

Field Surveys of Bush Lima Bean Reveal Shortcomings in Weed Management

HortScience · 2025-06-13

To understand the scope of weed problems in commercial lima bean ( Phaseolus lunatus L.) production, lima bean fields were surveyed for weeds that escaped control near the time of crop harvest (hereby called residual weeds) from 2019 to 2022 in the Mid-Atlantic and the Midwest, two major production regions of the United States. Overall weed abundance was determined based on relative density, frequency, and uniformity throughout surveyed fields. Density was the number of individual plants in overall quadrats in fields with that weed. Frequency was the number of fields with that weed species recorded in overall surveyed fields. Uniformity was the number of quadrats with a particular weed species in overall quadrats. Approximately 52 weed species were observed, and differences in weed communities were observed between the Mid-Atlantic and Midwest regions. Significant weeds in the Mid-Atlantic region included common chickweed [ Stellaria media (L.) Vill], amaranth species ( Amaranthus spp.), and morningglory species ( Ipomoea spp.). Significant weeds in the Midwest region were foxtail species ( Setaria spp.), common lambsquarters ( Chenopodium album L.), and amaranth species. Crop management practices used in the fields were obtained from collaborating farmers and vegetable processors. Widely adopted mechanical weed control methods included spring (preplant) tillage and interrow cultivation. Common herbicides included preemergent applications of S- metolachlor and halosulfuron-methyl. Bentazon was the most common herbicide applied postemergence. Classification and regression tree modeling were used to determine linkages among residual weeds and management factors. Despite the adoption of multiple chemical and mechanical weed control methods, this survey revealed extensive weed problems in many production fields. Greater diversification of integrated weed management systems is needed, especially for the control of amaranth species. This survey will help guide future research efforts for weed control in lima bean production.

Crop and Weed Management Practices of Snap Bean (Phaseolus vulgaris) Production Fields in the United States

HortScience · 2025-01-31 · 3 citations

Agronomic and weed management practices employed by growers in the production of snap bean ( Phaseolus vulgaris ) for the processing industry are poorly characterized. To address this knowledge gap, records of agronomic and weed management practices from 358 snap bean fields were obtained from collaborating processors. These fields encompassed three production regions in the United States: the Northwest (NW), Midwest (MW), and Northeast (NE). The obtained records were formatted to be more suitable for presentation or analysis. Forty cultivars were used across all three regions, primarily of green round podded type (∼90% of all fields). However, it was common for only relatively few cultivars to be widespread in each region. Seeding rates were substantially higher (by more than 100,000 plants/ha on average) in the NW region. Crop row widths were also narrower in the NW region compared with other regions. Planting and harvest occurred across a wide range of dates in all three production regions, with the NW having a delay of ∼10 days. The most common crop in rotation with snap bean was usually some type of corn, although the NW region had more variability in crop rotation. Spring tillage and irrigation were commonly used practices across all regions. Weed management was dominated by the use of interrow cultivation and a narrow spectrum of preemergence and postemergence herbicides. However, interrow cultivation was not used as much in the NW compared with the other two regions. Snap bean grown in the NW production region showed a departure in agronomic and weed management practices compared with the MW and NE production regions.

Climate change exacerbates the environmental impacts of agriculture

Science · 2024 · 405 citations

• Natural resource economics
• Environmental science
• Environmental resource management

Agriculture's global environmental impacts are widely expected to continue expanding, driven by population and economic growth and dietary changes. This Review highlights climate change as an additional amplifier of agriculture's environmental impacts, by reducing agricultural productivity, reducing the efficacy of agrochemicals, increasing soil erosion, accelerating the growth and expanding the range of crop diseases and pests, and increasing land clearing. We identify multiple pathways through which climate change intensifies agricultural greenhouse gas emissions, creating a potentially powerful climate change-reinforcing feedback loop. The challenges raised by climate change underscore the urgent need to transition to sustainable, climate-resilient agricultural systems. This requires investments that both accelerate adoption of proven solutions that provide multiple benefits, and that discover and scale new beneficial processes and food products.

Weed communities of snap bean fields in the United States

Weed Science · 2024-11-15 · 3 citations

Abstract Weeds are one of the greatest challenges to snap bean ( Phaseolus vulgaris L.) production. Anecdotal observation posits certain species frequently escape the weed management system by the time of crop harvest, hereafter called residual weeds. The objectives of this work were to (1) quantify the residual weed community in snap bean grown for processing across the major growing regions in the United States and (2) investigate linkages between the density of residual weeds and their contributions to weed canopy cover. In surveys of 358 fields across the Northwest (NW), Midwest (MW), and Northeast (NE), residual weeds were observed in 95% of the fields. While a total of 109 species or species-groups were identified, one to three species dominated the residual weed community of individual fields in most cases. It was not uncommon to have &gt;10 weeds m −2 with a weed canopy covering &gt;5% of the field’s surface area. Some of the most abundant and problematic species or species-groups escaping control included amaranth species such as smooth pigweed ( Amaranthus hybridus L.), Palmer amaranth ( Amaranthus palmeri S. Watson), redroot pigweed ( Amaranthus retroflexus L.), and waterhemp [ Amaranthus tuberculatus (Moq.) Sauer]; common lambsquarters ( Chenopodium album L.); large crabgrass [ Digitaria sanguinalis (L.) Scop.]; and ivyleaf morningglory ( Ipomoea hederacea Jacq.). Emerging threats include hophornbeam copperleaf ( Acalypha ostryifolia Riddell) in the MW and sharppoint fluvellin [ Kickxia elatine (L.) Dumort.] in the NW. Beyond crop losses due to weed interference, the weed canopy at harvest poses a risk to contaminating snap bean products with foreign material. Random forest modeling predicts the residual weed canopy is dominated by C. album , D. sanguinalis , carpetweed ( Mollugo verticillata L.), I. hederacea , amaranth species, and A. ostryifolia . This is the first quantitative report on the weed community escaping control in U.S. snap bean production.

Natural Soil Amendments to Reduce Nitrate Leaching in Potato Production

American Journal of Potato Research · 2024-05-22

Cheatgrass Inhibits Wild Potato (Solanum jamesii) Tuber Sprouts

American Journal of Potato Research · 2023-01-10