A. Sophie Westbrook

Türkiye has the sixth largest area of grape production in the world. The country produces more than 3.4 × 10 ⁹ kg of grapes on 377,843 hectares, but weeds are a major limitation to achieving greater yield and better quality grapes. To better understand the composition and distribution of the weed seedbank in the soil profile, weed flora and soil seedbank dynamics were assessed across 25 vineyards in Elazığ Province. Soil samples were collected from each vineyard in 2023 at two soil depths (0 to 7.5 cm and 7.5 to 15 cm). Field surveys were carried out in spring and summer 2024 to determine the density and frequency of weed species. A total of 53 weed species from 22 families were recorded in the seedbanks of all 25 vineyards combined. Annual species comprised 75.5% of the total. In field surveys, 85 weed species were identified in spring, and 34 were identified in summer 2024. Species in the Poaceae and Asteraceae families were most abundant. In our vineyard systems, effective long-term weed management should combine appropriate tillage techniques and targeted weed control measures to prevent seedbank replenishment and minimize weed infestations.

We studied the impacts of uncrewed aerial vehicle (UAV)‐applied triclopyr + fluroxypyr on rangeland weeds and other forbs in native tallgrass prairie. Two rates were tested: high (0.63 kg ae ha ⁻¹ triclopyr + 0.21 kg ae ha ⁻¹ fluroxypyr) and low (0.21 kg ae ha ⁻¹ triclopyr + 0.07 kg ae ha ⁻¹ fluroxypyr). We evaluated injury to established plants (Baldwin's ironweed [ Vernonia baldwinii Torr.], goldenrod [ Solidago spp.], leadplant [ Amorpha canescens Pursh], western ragweed [ Ambrosia psilostachya DC.], and white sagebrush [ Artemisia ludoviciana Nutt.]) and potted seedlings (alyssum [ Lobularia maritima (L.) Desv.], Baldwin's ironweed, common evening primrose [ Oenothera biennis L.], common milkweed [ Asclepias syriaca L.], and sericea lespedeza [ Lespedeza cuneata (Dum. Cours.) G. Don]). For established plants, herbicide treatments did not impact percentage cover of individual species, although they did marginally increase the rate of decline in total forb cover ( p = 0.05). The high herbicide rate increased the rate of increase in visual injury in all species ( p < 0.05). For seedlings, visual injury was observed at both herbicide rates for Baldwin's ironweed, common milkweed, and sericea lespedeza ( p < 0.01). Water‐sensitive papers revealed low and variable levels of spray coverage with apparent drift onto control plots. Normalized difference vegetation index slightly increased over time in the control treatment, whereas it decreased over time at the low herbicide rate and especially the high herbicide rate ( p < 0.001). Advances in UAV technology will continue to promote spraying and sensing applications in rangeland environments, although the potential for nontarget impacts should be incorporated into management guidance.

Palmer amaranth ( Amaranthus palmeri S. Watson) is among the most economically damaging weeds in the United States and has evolved resistance to numerous herbicides, including glyphosate. This fast-growing species has expanded its range into different regions, including New York State, where glyphosate-resistant (GR) populations are now found. We evaluated how temperature modifies two components of weed risk, sensitivity to glyphosate and competitiveness against corn ( Zea mays L.), under growth chamber conditions. First, we performed a dose–response study testing glyphosate efficacy for a GR A. palmeri biotype from New York State and a glyphosate-susceptible (GS) biotype from Nebraska. Tests were conducted at low (25/15 C), medium (30/20 C), and high (35/25 C) day/night temperatures. The nontreated GS biotype produced greater biomass at low versus high temperatures. This biotype was highly sensitive to glyphosate across all temperatures. In contrast, biomass of the nontreated GR biotype did not vary with temperature. This biotype was less sensitive to glyphosate across all temperatures. Our second study tested whether temperature modifies the impacts of A. palmeri on corn biomass at four planting densities (zero, one, two, or four A. palmeri with one corn plant). We used the same three temperature regimes and the same two A. palmeri biotypes as the dose–response study. There was no evidence that the biotypes, at any planting density, were more competitive with corn under elevated temperatures. In fact, the biomass of A. palmeri decreased with increasing temperatures while corn biomass did not vary. In the competition study, the GS biotype from Nebraska had higher biomass than the GR biotype from New York. Overall, these results do not support the hypothesis that increasing temperatures would exacerbate the risk posed by the tested A. palmeri biotypes in corn. Instead, these two A. palmeri biotypes may be highly problematic under temperatures already occurring in New York State.

Biodiversity plantings are effective methods of enhancing on-farm biodiversity. However, farmers are often hesitant to place them adjacent to crop fields due to concerns that they may harbor problematic weeds and pest arthropods, or that the intentionally planted species may escape into the crop and act as weeds. The objective of this research was to compare weed and arthropod communities in planted versus conventionally managed field margins at two sites in New York State. Planted treatments were seeded with either native wildflowers or grasses and then either mowed infrequently or unmanaged after planting. Conventional field margin management treatments included infrequent and frequent mowing, glyphosate application, and an unmanaged control. Measurements included both seedbank and aboveground plant density and diversity, plant biomass, and the abundance of both beneficial and pest arthropods. Pest arthropod abundance both in the margin and in the crop was not affected by the field margin management strategy. Arthropod abundance and plant richness and diversity, both within fields and field margins, were not strongly affected by the field margin management method. Once the plantings were established, weed density was lower within planted margins than conventionally managed margins (P = 0.0002), with a difference of 92.8% per 0.5 m ² in 2025. Treatment affected weed biomass (P = 0.002), but treatment means differed significantly at only one site in 2024 according to Tukey’s HSD. Overall, our results indicate that the establishment of field margin plantings is unlikely to exacerbate weed pressure from field margins.

Perennial field margin plantings are known to contribute to both biodiversity and ecosystem services in agricultural landscapes, but the duration of their functionality is not clear, especially in the Northeastern region of the United States. A four-year study was conducted at Cornell University from 2022 through 2025 to investigate the effects of seeding density and seed mix composition on the establishment and development over time of perennial field margin plantings established in 2022 under weedy conditions. In the first two years, we found that while weeds negatively impacted establishment, planted strips eventually enhanced biodiversity despite this initial negative impact. To assess longer-term impacts, aboveground density, diversity, and biomass measurements were collected in 2024 and 2025. Four years after establishment, we found that as in the first two years, the highest densities of seeded species still occurred in flower strips with high seeding rates. Flower strips planted with native grass species at a high seeding rate tended to have less weed biomass than strips planted with a seed mix containing only wildflowers, especially at higher seeding rates. Contrary to expectations, planting native species did not increase alpha biodiversity measurements such as the Shannon diversity index. Although overall species richness did not differ across treatments, margins with native grass and wildflowers contained a greater number of seeded species. Our results suggest that the positive impacts on biodiversity associated with field margin plantings may require management of weeds within plantings, despite the existence of a small suppressive effect on weeds by high-density plantings containing native grass species. However, seeded dicot species were consistently found even under weedy conditions, suggesting that the presence of weeds in flower strips does not prevent them from enhancing the floral resources available to pollinators within field margins.

Many rangeland weeds exhibit physiological seed dormancy that is released by cold winter temperatures. Species vary in their cold stratification requirements, leading to variation in the amount and timing of weed germination in the spring. We performed a replicated growth chamber study testing the impacts of stratification duration (0, 2, 4, 6, or 12 wk) on germination of common evening primrose ( Oenothera biennis L.), Baldwin’s ironweed ( Vernonia baldwinii Torr.), tall goldenrod ( Solidago altissima L.), and hollow Joe-pye weed [ Eutrochium fistulosum (Barratt) E.E. Lamont]. Species (P < 0.001), stratification treatment (P < 0.001), and the interaction between species and stratification treatment (P < 0.001) jointly impacted the probability of germination. Stratification did not influence germination of O. biennis , although non-stratified seeds took longer to germinate. For V. baldwinii , positive effects of stratification were similar regardless of stratification duration (2 to 12 wk), although seeds stratified for 12 wk germinated fastest. Dissection revealed that most stratified V. baldwinii seeds failing to germinate did not appear to be viable. Germination of S. altissima was maximized at 4 wk of stratification, although seeds stratified for 12 wk again germinated fastest. In E. fistulosum , germination was maximized at 12 wk of stratification and time to germination decreased with increasing stratification duration. Overall, these results show flexible stratification requirements in these rangeland weeds, although longer stratification periods are generally associated with greater and faster germination. These data may be useful in predicting the timing of weed emergence to help guide management operations.

Effective weed management is critical to the long-term productivity of organic grain cropping systems. The Cornell Organic Cropping Systems Experiment was initiated in 2005 at the Musgrave Research Farm in Aurora, NY, to compare four organic cropping systems that differed primarily in intensity of mechanical weed management and soil nutrient inputs. A 3-yr rotation of corn (Zea mays L.), soybean [Glycine max (L.) Merr.], and spelt (Triticum spelta L.)/red clover (Trifolium pratense L.) was grown in all systems. The four systems were characterized by High Fertility (red clover green manure, composted poultry manure, and commercial organic fertilizer to reach recommended fertility levels), Low Fertility (no fertility inputs other than the red clover and starter fertilizer for corn), Enhanced Weed Management (fertility management as in Low Fertility with additional tillage and cultivation and a higher spelt seeding density), and Reduced Tillage (primarily ridge tillage with different green manure crops). The experiment included two crop rotation entry points, enabling two of the three crops in the rotation to be grown every year. Results from the first two rotation cycles show that, in most cases, weed abundance and diversity increased during the transition to organic production, especially in the Reduced Tillage system. Perennial weeds increased in corn and soybean in the Reduced Tillage system in the second rotation cycle, which contributed to its poor performance relative to the three other systems. Our results suggest that increased soil disturbance, including tillage and cultivation in corn and soybean, plays an important role in reducing weed populations, whereas high fertility levels may exacerbate weed problems. These findings underscore the importance of balancing weed and nutrient management in enabling sustainable organic grain crop production.

For many invasive plants, seed dormancy and persistence facilitate population expansion. These traits also complicate control efforts, as new seedlings may continue to emerge for years after the removal of existing plants. The maximum longevity of invasive plant seeds may range from years to decades. However, few seeds emerge after such a long time under field conditions. We conducted a field experiment testing the impact of seed burial depth on emergence of meadow knapweed ( Centaurea × moncktonii C.E. Britton) and spotted knapweed [ Centaurea stoebe L. ssp. micranthos (Gugler) Hayek] over 3 yr. For C. × moncktonii , emergence (raw data corrected for seed viability) was 57% at 0 cm, 28% at 2 cm, 3% at 4 cm, and 0% at 8 cm. For C. stoebe , emergence was 84% at 0 cm, 11% at 2 cm, 4% at 4 cm, and 0% at 8 cm. The primary flush of seedlings, averaged over Centaurea species and burial depths, occurred during the first few months of the study in fall 2018. Little emergence occurred after spring/summer 2019, although the study continued through spring/summer 2021. Our findings clarify the maximum burial depth from which these Centaurea species can emerge and demonstrate that emergence is concentrated in the first year after seed production.

The troublesome weed Johnsongrass [Sorghum halepense (L.) Pers.] is predicted to expand its range under climate change. In the process, it is likely to become more competitive in corn (Zea mays L.) production areas of the northeastern United States and southern Canada. A replicated greenhouse experiment was conducted to measure interspecific and intraspecific competition between an S. halepense biotype from central New York State (northern range edge) and corn under drought and well-watered conditions. Drought stress significantly reduced the biomass and height of corn and S. halepense in both rounds of the experiment (P < 0.001). Drought stress increased the root-to-shoot ratio of S. halepense (P < 0.001) and reduced the root-to-shoot ratio of corn (P < 0.001). In one run of the experiment, corn produced 19.3% more aboveground biomass (P < 0.001) and 6.6% more height (P < 0.001) when competing with an S. halepense plant (interspecific competition) than when competing with a second corn plant (intraspecific competition). Drought conditions increased the advantage of corn plants grown under interspecific relative to intraspecific competition (P = 0.012). In that round of the experiment, biomass of S. halepense was 12.9% higher under intraspecific competition than interspecific competition in the well-watered treatment and 15.5% higher under intraspecific competition than interspecific competition in the drought treatment (main effect of competition, P = 0.002). Differences between competition treatments were smaller in the other round of the experiment (P > 0.05). Our findings suggest that the New York S. halepense biotype used in this study may not be as competitive as biotypes found in this weed’s range core in more southern regions of the United States. However, anticipated effects of climate change may increase the abundance and competitiveness of this species in the northeastern United States.