Broadleaf Weeds Research Articles

Development of an ic-ELISA and immunochromatographic assay strip for the rapid detection of chloridazon in oranges and celery.

Chloridazon (CLZ) is a selective herbicide used in the control of annual broadleaf weeds. The misuse or abuse of CLZ may result in the accumulation of CLZ in crops and water, which can pose a risk to human health. In this study, a hapten of CLZ with three carbon spacer arms was designed and a highly sensitive and specific antibody against CLZ was prepared with a half-maximal inhibitory concentration of 0.630 ng mL-1 and a linear range of 0.181-2.195 ng mL-1.Based on this antibody, we developed an immunochromatographic assay (ICA) strip for the detection of CLZ in oranges and celery. Under optimized conditions, the visual limit of detection was 2 ng mL-1 and 10 ng mL-1 in oranges and celery, respectively, and the cut-off value was 50 ng mL-1. In CLZ-spiked samples and the recovery test, the results of the ICA strip were consistent with those of indirect competitive enzyme-linked immunosorbent assay (ic-ELISA). Therefore, the ICA strip developed in our study represents an efficient and reliable method for the rapid screening of CLZ in oranges and celery.

Control of multiple-herbicide-resistant waterhemp with acetochlor-based herbicide mixtures in soybean

Abstract Waterhemp has evolved resistance to Group 2, 5, 9, 14, and 27 herbicides in Ontario, Canada, making control of this challenging weed even more difficult. Acetochlor is a Group 15, chloroacetanilide herbicide that has activity on many small-seeded annual grasses and some small-seeded annual broadleaf weeds, including waterhemp. The objective of this study was to ascertain if acetochlor mixtures with broadleaf herbicides (dicamba, metribuzin, diflufenican, sulfentrazone, or flumioxazin), applied preemergence (PRE), increase multiple-herbicide-resistant (MHR) waterhemp control in soybean. Five trials were conducted over 2 yr (2021 and 2022). The acetochlor mixtures caused ≤7% soybean injury, except acetochlor + flumioxazin, which caused 19% soybean injury. Acetochlor applied PRE controlled MHR waterhemp 89% at 4 wk after application (WAA). Dicamba, metribuzin, diflufenican, sulfentrazone, or flumioxazin controlled MHR waterhemp 59%, 67%, 58%, 64%, and 86%, respectively, at 4 WAA. Acetochlor applied in a mixture with dicamba, metribuzin, diflufenican, sulfentrazone, or flumioxazin provided good to excellent control of MHR waterhemp; control ranged from 91% to 98% but was similar to acetochlor applied alone. Acetochlor alone reduced MHR waterhemp density and biomass 98% and 93%; acetochlor + flumioxazin reduced waterhemp density and biomass by an additional 2% and 7%, respectively. This research concludes that acetochlor applied in a mixture with flumioxazin was the most efficacious mixture evaluated for MHR waterhemp control.

Channel Attention GAN-Based Synthetic Weed Generation for Precise Weed Identification.

Weed is a major biological factor causing declines in crop yield. However, widespread herbicide application and indiscriminate weeding with soil disturbance are of great concern because of their environmental impacts. Site-specific weed management (SSWM) refers to a weed management strategy for digital agriculture that results in low energy loss. Deep learning is crucial for developing SSWM, as it distinguishes crops from weeds and identifies weed species. However, this technique requires substantial annotated data, which necessitates expertise in weed science and agronomy. In this study, we present a channel attention mechanism-driven generative adversarial network (CA-GAN) that can generate realistic synthetic weed data. The performance of the model was evaluated using two datasets: the public segmented Plant Seedling Dataset (sPSD), featuring nine common broadleaf weeds from arable land, and the Institute for Sustainable Agro-ecosystem Services (ISAS) dataset, which includes five common summer weeds in Japan. Consequently, the synthetic dataset generated by the proposed CA-GAN obtained an 82.63% recognition accuracy on the sPSD and 93.46% on the ISAS dataset. The Fréchet inception distance (FID) score test measures the similarity between a synthetic and real dataset, and it has been shown to correlate well with human judgments of the quality of synthetic samples. The synthetic dataset achieved a low FID score (20.95 on the sPSD and 24.31 on the ISAS dataset). Overall, the experimental results demonstrated that the proposed method outperformed previous state-of-the-art GAN models in terms of image quality, diversity, and discriminability, making it a promising approach for synthetic agricultural data generation.

Influence of Different Levels of Cyanazine on Blood Picture of Labeo rohita

The freshwater fish Labeo rohita is found in Asian countries and around the world. Cyanazine herbicide produce extensive threat to freshwater fishes and used to control annual grasses and broadleaf weeds. Subsequently, freshwater ecosystem was facing potential risk due to extensive application of this herbicide. Objective: To find the toxic effects of cyanazine on hematological parameters of Labeo rohita. Methods: For this purpose, fish was divided into four groups. Ten fish were introduced into each group. The group 1 was taken as control group. The group 2, 3 and 4 were treated groups and exposed to different concentration of cyanazine 3µgL-1, 6µgL-1 and 8µgL-1 respectively. Results: The current study showed that WBC, RBC, HGB and HCT increased while the MCV, MCH, MCHC and PLT decreased significantly. Conclusions: Hematological parameters of L. rohita were significantly affected by exposure to Cyanazine. These alterations indicate that Cyanazine can potentially disrupt the fish's hematological balance, which could have implications for its overall healt

Pengaruh herbisida bentazon 400 g/l + mcpa 60 g/l terhadap gulma, pertumbuhan dan hasil tanaman padi (Oryza sativa L.)

Weeds are one of the obstacles in rice cultivation because they can reduce rice yields both in quality and quantity. Weeds compete in terms of necessities of life such as water, nutrients and sunlight. This study aims to determine the effect of betazon 400 g/l + MCPA 60 g/l in controlling weeds and the growth of paddy rice. The research was conducted in Palasah Village, Kertajati District, Majalengka Regency, West Java. The experiment used a one-factor Randomized Block Design (RBD) with seven treatments and four replications. The experiment consisted of five treatments of bentazone 400 g/l + MCPA 60 g/l at a dose of 1.5 L/ha, 2.0 L/ha, 2.5 L/ha, 3.0 L/ha, 3.5 L/ha, the comparison is in the form of manual control and without weed control. The data obtained if there is a significant difference will be further tested using the testDuncan Multiple Range Test (DMRT) at the level of 5%. The results showed that the application of the herbicide Bentazone 400 g/l + MCPA 60 g/l at a dose of 1.5 L/ha was able to suppress the growth of broadleaf weeds (Lindernia crustarcea, Spenoclia zeylanica and Marsilea crenata), sedge weeds (Cypress iria and Fimbristylis miliacea) and does not cause symptoms of toxicity (phytotoxicity) to rice plants which so that they do not interfere with their growth.

Weed management strategies in elephant foot yam (<i>Amorphophallus paeoniifolius</i>) under different agro environments in India

In elephant foot yam [Amorphophallus paeoniifolius (Dennst.) Nicolson], weeds are the major constraints cause yield reduction up to 100% due to its very slow initial sprouting, establishment and plant growth. Information on proper weed management in elephant foot yam in India is limited as its commercial cultivation started very recently. For arriving at suitable and better weed control, field experiments were conducted for 3 growing seasons (2019 to 2021) at ICAR-Central Tuber Crops Research Institute, Thiruvananthapuram, Kerala with 8 treatments in 6 different agro-climatic zones of India. The treatments included a combination of pre emergence (PE) and post emergence (POE) herbicides, PE followed by hand weeding (HW), intercropping followed by POE, HW with POE, POE alone, and weed control ground cover cloth mulch (WCGCC), three HW, and a weedy check were included for comparison. Weed flora was dominated by broad-leaf weeds, Digera arvensis (L.), Commelina benghalensis (L.); grasses, Pennisetum pedicellatum Trin., Cynodon dactylon (L.) pers.; and the sedge, Cyperus rotundus (L.), in most of the locations. Pooled analysis of data collected over different locations indicated that the lower mean weed biomass (21.24 g/m) and higher mean corm yield (35.13 t/ha), higher mean net income (`0.326 million/ha) were recorded with weed control ground cover mulch and higher mean B:C ratio (2.39) by application of post emergence herbicide at 30, 60 and 90 days after planting (DAP).

A Sensitive and Specific Monoclonal Antibody Based Enzyme-Linked Immunosorbent Assay for the Rapid Detection of Pretilachlor in Grains and the Environment.

Pretilachlor is a chloroacetamide herbicide mainly used for weed and broadleaf weed control in rice, that is widely utilized in China. In order to detect the residue of pretilachlor in the environment and food, a highly sensitive and specific monoclonal antibody (mAb) against pretilachlor was prepared, and the half maximum inhibitory concentration (IC50) of the monoclonal antibody was validated to be 31.47 ± 2.35 μg/L. An indirect competitive ELISA (ic-ELISA) based on the antibody with a linear range of 6.25~100 μg/L was developed. The specificity of the antibody was explained by computer simulations and experimental validation. The mAb exhibited negligible cross-reactivity towards alachlor, acetochlor, propisochlor, butachlor, and metalaxyl, and the limits of detection (LOD) for pretilachlor in lake, rice, and soil samples were 4.83~5.23 μg/L. The recoveries of all samples were 78.3~91.3%. The reliability of the ic-ELISA method for residue detection of pretilachlor in the environment and grains was confirmed using high performance liquid chromatography.

Synthesis, Herbicidal Activity against Barnyard Grass, and Photolytic Behavior of Aryl 2,6-Dipyrimidinoxybenzoates.

In this study, we investigated the characteristics and herbicidal potential of bispyribac phenolic esters, which belong to the 2-(pyrimidin-2-yloxy)benzoic acid (PYB) class of acetohydroxyacid synthase (AHAS-)-inhibiting herbicides. These herbicides are primarily used for controlling Poaceae and broadleaf weeds. Among them, bispyribac-sodium stands out as a representative in this class. Surprisingly, other bispyribac esters, including alkanol and phenol esters exhibit considerably reduced herbicidal activity compared to bispyribac-sodium. In contrast, oxime esters (e.g., pyribenzoxim) demonstrate high activity. To further understand and develop novel PYB herbicides, we synthesized and screened a series of bispyribac phenolic esters while investigating their photochemical behaviors. Several compounds displayed excellent herbicidal activity, with compounds Ia-19 and Ic showing impressive 90% effective dosages for fresh weight inhibition of barnyard grass, measuring 0.55 and 0.60 g a.i./hm2, respectively. These values were approximately half of bispyribac-sodium or pyribenzoxim. The results indicate that the herbicidal activity of phenolic esters is influenced by both their binding ability to the AHAS enzyme and their decomposition into bispyribac acid. For instance, bispyribac phenol ester exhibited considerably reduced receptor affinity compared to bispyribac-sodium, and faced challenges in transforming into bispyribac acid, explaining its diminished herbicidal activity. However, introducing a photosensitive nitro group led to a complete transformation. This modification improved its affinity with AHAS and accelerated its decomposition into bispyribac acid, further accelerated by photocatalysis. Consequently, nitro-containing compounds displayed heightened herbicidal activity. The findings from this study open possibilities for structural optimization of phenolic esters through quantitative structure-activity relationship analysis, potentially regulating their activity-releasing period. Furthermore, the high activity of aromatic heterocyclic esters offers new insights into developing novel PYB herbicides.

Early Detection of Dicamba and 2,4-D Herbicide Drifting Injuries on Soybean with a New Spatial–Spectral Algorithm Based on LeafSpec, an Accurate Touch-Based Hyperspectral Leaf Scanner

In soybeans, off-target damage from the use of dicamba and 2,4-D herbicides for broadleaf weed control can significantly impact sensitive vegetation and crops. The early detection and assessment of such damage are critical for plant diagnostic labs and regulatory agencies to inform regulated usage policies. However, the existing technologies that calculate the average spectrum often struggle to detect and differentiate the damage caused by these herbicides, as they share a similar mode-of-action. In this study, a high-precision spatial and spectral imaging solution was tested for the early detection of dicamba and 2,4-D-induced damage in soybeans. A 2021 study was conducted using LeafSpec, a touch-based hyperspectral leaf scanner, to detect damage on soybean leaves. VIS-NIR (visible–near infrared) hyperspectral images were captured from 180 soybean plants exposed to nine different herbicide treatments at different intervals after spraying. Leaf damage was distinguished as early as 2 h after treatment (HAT) using pairwise partial least squares discriminant analysis (PLS-DA) models based on spectral data. Leaf color distribution, texture, and morphological features were analyzed to separate herbicide dosages. By fully exploiting the spatial and spectral information from high-resolution hyperspectral images, classification accuracy was improved from 57.4% to over 80% for all evaluation dates. This work demonstrates the potential and advantages of using spectral and spatial features of LeafSpec hyperspectral images for the early and accurate detection of herbicide damage in soybean plants.

Effect of Some Chemical Herbicides on the Weeds Accompanying the Field's Peanut Crop

A field experiment was conducted during the spring season of 2021 in a selected field of preparative Ibn Al-Bitar occupational/ Al-Hussainiya region in Holy Karbala. The experiment involved cultivating peanut plants (Arachis hypogaea L.), specifically a local variety, in soil characterized by a clay loam texture. The experiment aimed to determine the most effective chemical herbicides for controlling weed growth in conjunction with the Peanut crop. The experiment utilized a randomized complete block design (RCBD) with three replications. The study encompassed six conditions: weedy and weed-free, which were under manual control for the entire duration of the growing season. Furthermore, there were treatments that involved the administration of chemical herbicides before planting, specifically Trifluralin and Pendimethalin, which were applied ten days before the planting phase. Additionally, post-planting herbicides, namely Oxyfluorfen and Clethodim, were sprayed during the vegetative growth phase of the plant as well as at the initiation of the flowering stage. The herbicides were administered according to the prescribed dosages. The findings demonstrated significant differences in the management procedure utilizing chemical herbicides throughout a 30-day period of applying said herbicides. This discrepancy became apparent when evaluating the two herbicides, specifically Oxyfluorfen and Pendimethalin, which produced the lowest quantity of broad-leaf weeds, with a recorded density of 4.6 and 7.6 plants m-2, respectively. Additionally, the results demonstrated that notable disparities were observed after 60 days from the application of herbicides. Specifically, the herbicides Pendimethalin and Oxyfluorfen exhibited the lowest density of broad-leaf weeds, with a count of 4.6 and 6.0 m-2 plants, respectively. Moreover, the impact of herbicides on narrow-leaf weed was examined at 30 and 60 days post-spraying. There was no significant difference in the means of the herbicides, and the herbicides Oxyfluorfen and Pendimethalin yielded the least density of broad leaf weeds after 90 days of herbicide application, with quantities of 6.0 and 6.3 plant m-2, respectively. Similarly, concerning narrow-leaf weed density on the same date, the herbicides Trifluralin, Clethodim,, and Ox-yfluorfen exhibited superiority in achieving the lowest density of narrow-leaf weeds, with quantities of 5.0, 5.3, and 5.6 plant m-2, respectively. Furthermore, no statistically significant difference was observed among these herbicides. The findings demonstrate the superiority of the herbicides Oxyfluorfen and Pendimethalin in achieving the highest percentage of control for broad-leaf weeds after 30, 60, and 90 days of herbicide application. Regarding the specific dates for the narrow-leaf weeds, the herbicides Oxyfluorfen, Clethodim, and Trifluralin exhibited superiority in providing optimal control. In contrast to alternative treatments involving herbicides, the herbicide Oxyfluorfen showcased the most diminished mean mass and the utmost level of hindrance on both extensive and limited-leafed weeds. Keywords: Herbicides; Oxyfluorfen; Pendimethalin; Clethodim; Trifluralin; Weeds; Narrow leaf; Broad leaf.

Suppression of weed and insect populations by living and straw mulches in sesame (Sesamum indicum L.)

In order to evaluate the effect of different weed management treatments on weeds, pest and natural enemies populations in sesame (Sesamum indicum L.), a 2-year study was conducted in East Azarbaijan, Iran in 2020–2021. The study was conducted based on randomized complete block design with four replications. The weed management treatments consisted of trifluralin use (960 g ai ha−1), wheat straw mulch (WSM), living mulches of fenugreek (Trigonella foenum-graecum L.) (FLM), bitter vetch (Vicia ervilia L.) (VLM), calendula (Calendula officinalis L.) (CLM) and one-time hand weeding (OHW). The effect of weed management treatment was significant on densities of insect pests, natural enemies and weed and also weed biomass and sesame seed yield. The lowest densities of insect pests including Myzus persicae, Brevicoryne brassicae, Helicoverpa armigera and Spodoptera exigua were observed in CLM treatment. Also, the highest densities of natural enemies Coccinella septompunctata, Coccinella undecimpunctata and Orius niger were observed in CLM treatment. The highest reductions in grass (51.0%), broadleaf (72.0%), and total (62.6%) weed biomasses and highest seed yield (1456 kg ha−1) were obtained in OHW. The seed yields in CLM and WSM treatments were not significantly different with trifluralin treatment and could be recommended in sustainable production of sesame.

Study of the Effect of Trifloralin Herbicide, Seed Rate and Planting Distances in Controlling Broad-Leaf Weeds Associated with Wheat (Triticum aestivum L.) Under the Conservation Agriculture System

The study was conducted in the fields of one of the farmers in order to control the broad Weeds associated with the wheat crop by chemical and agricultural methods and with a conservative cultivation system for the seasons 2018/2019 and 2019/2020, and the study included three factors: the first factor is the Trifloraline herbicide and at two levels (0, 1248) cm3 / ha, the second factor rates the effectiveness of the herbicide, and the third factor rates the effectiveness of the cultivation system. Important findings are summarized below. The study was conducted using the system of global experiments in the split-split plots, with seeding at three levels (80, 100, and 120) kg / ha, and the third factor, planting distances at two levels (15 and 30) cm between the lines, with design of complete random sectors and with three replications; Herbicide treatment reduced all traits significantly compared to comparison treatment. Seeding rate increased broad-leaf weeds and side branches and decreased bush susceptible leaf dry weight. All traits improved at 30 cm between planting lines. Interaction achieved. In the second season, the herbicide treatment and 120 kg/ha seed rate reduced broadleaf weed dry weight. The herbicide treatment and 15-cm distance reduced all traits and seasons. In the second season, the interaction between the seed rate of 120 kg/ha and the distance of 15 cm between the planting lines reduced the dry weight of the broad-leaf weed, while the herbicide treatment and the seed rate of 80 kg/ha did the same. In the second season, broad-leaved weeds decreased in dry weight by 15 cm.

Efficacy of different herbicides for controlling grass predominant weed flora and achieving higher production in dual purpose linseed under mid hills of Himachal Pradesh

A field experiment was conducted to study the effect of herbicide treatments on the weed flora and the production of the dual-purpose Linseed. The results revealed that grassy weeds viz., Phalaris minor, Lolium temulentum and Avena ludoviciana constituted 43.2, 23.2 and 17.2% of the total weed flora at 90 DAS. Among the broadleaf weeds, Vicia sativa and Spergulla arvensis constituted about 8.4% of total weed flora. As the crop was mainly infested with grassy weeds, effective control of total weeds with the application of clodinafop 60 g/ha (Post.), pendimethalin 1.0 kg/ha (Pre.) and isoproturon 1.25 kg/ha (Post.) as equivalent to hand weeding twice resulted in significantly higher seed, straw, biological, oil and fibre yield of Linseed. As far as the economics is concerned, significantly higher net returns of ₹ 54401 and 3051/ha and net returns per rupee invested (2.01 and 1.90) were obtained by statistically similar treatments of clodinafop 60 g/ha (Post.) and pendimethalin 1.0 kg/ha (Pre.), respectively. Thus, depending upon the situation in dual-purpose Linseed, selecting either of these appropriate chemicals is the better option for controlling grass-predominant weed flora and obtaining higher yields (seed and fiber) with better returns.

Citronella essential oil-based nanoemulsion as a post-emergence natural herbicide

A natural herbicide nanoemulsion was fabricated from citronella (Cymbopogon nardus L.) essential oil (CEO) and a nonionic surfactant Tween 60 mixed with Span 60 at hydrophilic-lipophilic balance 14 using a microfluidization method. The main constituents of CEO were citronellol (35.244%), geraniol (21.906%), and citronellal (13.632%). CEO nanoemulsion droplet size and polydispersity index (PI) were evaluated by dynamic light scattering (DLS). The smallest droplet size (33.2 nm, PI 0.135) was obtained from a microfluidizer at 20,000 psi, 7 cycles. Nanoemulsion droplet in transmission electron microscopy correlated with DLS confirmed CEO to successfully produce nanoemulsion. The herbicidal activity of the nanoemulsion as a foliar spray was evaluated against Echinochloa cruss-galli and Amaranthus tricolor as representative narrow- and broadleaf weed plants, both of which presented visual toxicity symptoms. The modes of action of the nanoemulsion were then determined in terms of membrane integrity (relative electrolyte leakage; REL), malondialdehyde (MDA), and photosynthetic pigment contents. The results showed increase in REL and MDA which indicated the destruction of the treated plants; additionally, chlorophylls and carotenoid contents were decreased. Consequently, CEO nanoemulsion may have the possibility to act as a natural herbicide resource, and natural herbicides from citronella nanoemulsions could be good alternatives for use in sustainable agriculture.

A systematic review of chemical weed management in peanut (Arachis hypogaea) in the United States: challenges and opportunities

AbstractHerbicides are the primary tool for controlling weeds in peanut (Arachis hypogaea L.) and are crucial to sustainable peanut production in the United States. The literature on chemical weed management in peanut in the past 53 yr (1970 to 2022) in the United States was systematically reviewed to highlight the strengths and weaknesses of different herbicides and identify current research gaps in chemical weed management. Residual weed control in peanut is achieved mainly with dimethenamid-P, ethalfluralin, pendimethalin, and S-metolachlor. More recently, the use of the protoporphyrinogen oxidase inhibitor flumioxazin and acetolactate synthase inhibitors, such as diclosulam, for residual weed control in peanut has increased considerably. Postemergence broadleaf weed control in peanut is achieved mainly with acifluorfen, bentazon, diclosulam, imazapic, lactofen, paraquat, and 2,4-DB, while the graminicides clethodim and sethoxydim are the major postemergence grass weed control herbicides in peanut. Although several herbicides are available for weed control in peanut, no single herbicide can provide season-long weed control due to limited application timing, lack of extended residual activity, variability in weed control spectrum, and rotational restrictions. Therefore, effective weed management in peanut often requires herbicide mixtures and/or sequential application of preplant-incorporated, preemergence, and/or postemergence herbicides. However, the available literature showed a substantive range in herbicide efficacy due to variations in environmental conditions and flushes of weed germination across years and locations. Despite the relatively high efficacy of herbicides, the selection of herbicide-resistant weeds is another area of increasing concern. Future research should focus on developing new strategies for preventing or delaying the development of resistance and improving herbicide efficacy within the context of climate change and emerging constraints such as water shortages, rising temperatures, and increasing CO2 concentration.

Comparative efficacy of different broad-spectrumweedicides on wheat crop and their impact on yield

Wheat Triticum aestivum L. is cereal and the predominant food crop in Pakistan, cultivated on an area of greater than one million hectares. A number of factors, including weeds, have affected yield in this crop. The weeds are competing with wheat plants for moisture, space, nutrients, light and a number of other growth factors which contribute to low yield and are determental to the quality of produce. A yield loss of 10 to 60% can be attributed to weeds. In fact, the only acceptable method of weed control will be the use of herbicides, due to rising labour and power costs. An experiment was laid out under irrigation system in Tehsil Samundri, to determine the broad and narrow leaf weed population in different area in wheat crop field and efficacy of five different broad spectrum weedicides during Rabi crop season. The experiment was laid out in Randomized Complete Block Design (RCBD) with three replications, with plot size of 200x 180 m2. Five different herbicides were applied as Atlantis 3.6 % WG @100 gm/ Acre, Isoproturan 50 % WP @ 800gm / Acre, Affinity 50 WP @ 800 gm/Acre, Proturon 50 % WP @ 800 gm/Acre and Pallas 45OD @ 160ml/Acre with control treatment. An average of 50.63/ m2 of weed population was observed. All weedicides significantly decreased weed population over control and maximum grain yield (40.55mon acre-1) was obtained where Affinity was applied @ 800 gm/acre. It was however statistically at par with the grain yield of 38.40mon acre-1 where Atlantis was applied @ 160 gm/ Ac. The control was obtained from all the herbalicidal applications. Therefore, in order to control broad and narrow leaf weeds and increase the yield of wheat it is recommended that Affinity and Atlantis be applied 800 and 160gm @acres respectively

Residual herbicides in corn and their effect on fall‐planted cover crop species

AbstractThe use of residual herbicides as a part of preemergence (PRE) and in‐season layered treatments has proven to be an effective strategy for controlling late‐emerging broadleaf weed species in annual crops. However, the use of residual PRE herbicides has the potential to negatively affect other crops within an annual two‐crop rotation, such as fall‐planted cover crops. The intent of this study was to determine if PRE herbicides commonly used in the upper Midwest United States would affect stand density, height, and biomass production of fall‐planted cover crops. Field studies were conducted at three locations that differed in soil type and climate. Four PRE herbicides were applied in silage corn (Zea mays L.) in the spring: dimethenamid‐P (single application), dimethenamid‐P + saflufenacil, acetochlor + clopyralid + mesotrione, and a layered treatment of dimethenamid‐P at planting and 30 days after first application. Three cover crops were planted in the fall following silage corn harvest with a no‐till drill: winter cereal rye (Secale cereale L.), winter camelina (Camelina sativa L.), and red clover (Trifolium pratense L.). Although some of the PRE HBs tested affected cover crop spring plant density and height in sandy soils, there was no difference in cover crop biomass production at termination between herbicide treatments, regardless of soil type. These results indicate that the application of these residual PRE herbicides for control of late‐emerging weed species did not interfere with cover crop biomass production as long as soil moisture was not limiting.

Investigating image-based fallow weed detection performance on Raphanus sativus and Avena sativa at speeds up to 30 km h−1

Site-specific weed control (SSWC) can provide considerable reductions in weed control costs and herbicide usage. Despite the promise of machine vision for SSWC systems and the importance of ground speed in weed control efficacy, there has been little investigation of the role of ground speed and camera characteristics on weed detection performance. Here, we compare the performance of four camera/software combinations using the open-source OpenWeedLocator platform – (1) default settings on a Raspberry Pi HQ camera (HQ1); (2) optimised software settings on a HQ camera (HQ2), (3) optimised software settings on the Raspberry Pi v2 camera (V2); and (4) a global shutter Arducam AR0234 camera (ARD) – at speeds ranging from 5 km h−1 to 30 km h−1. A combined excess green (ExG) and hue, saturation, value (HSV) thresholding algorithm was used for testing under fallow conditions using tillage radish (Raphanus sativus) and forage oats (Avena sativa) as representative broadleaf and grass weeds, respectively. ARD demonstrated the highest recall among camera systems, with up to 100 % recall for tillage radish and 91.6 % for forage oats at 5 km h−1. At 30 km h−1 ARD recall for forage oats declined (P < 0.05) by 12.4 %. There was no significant change for tillage radish. All cameras experienced a decrease in recall as speed increased. The highest rate of decrease was observed for HQ1 with 1.12 % and 0.90 % reductions in recall for every km/h increase in speed for tillage radish and forage oats, respectively. Detection of the ‘grassy’ forage oats was worse (P < 0.05) than the broadleaved tillage radish for all cameras. Despite the variations in recall, HQ1, HQ2, and V2 maintained near-perfect precision at all tested speeds. The variable effect of ground speed and camera system on detection performance of grass and broadleaf weeds, indicates that careful hardware and software considerations must be made when developing SSWC systems.

Double-spraying with different routes significantly improved the performance of both pre- and post-emergence wheat herbicides applied by unmanned aerial spraying systems

Unmanned aerial spraying systems (UASS) are one of the most important systems for herbicide applications. We applied pre-emergence (PRE) and post-emergence (POST) herbicides via an UASS to wheat (Triticum aestivum) fields, using different spraying volumes (22.5–60 L ha−1) and different spraying route strategies (one-time spraying or double spraying with two flight sorties routed in length and breadth). Both the spraying volume and route strategy significantly (P < 0.05) affected the control efficacy against grassy weeds and broadleaf weeds of both PRE and POST herbicides. Compared with manual spraying with a spraying volume of 450 L ha−1, the formulation of PRE herbicides (132 g·ai·ha−1 flufenacet + 132 g·ai·ha−1 diflufenican + 132 g·ai·ha−1 flurtamone) applied by the UASS with a spraying volume of 45 or 60 L ha−1 and adopting the double-spraying technique showed slightly higher or similar control efficacy against grassy and broadleaf weeds. The formulation of POST herbicides (9.75 g·ai·ha−1 florasulam + 9.75 g·ai·ha−1 halauxifen-methyl) showed control efficacies >98% against Galium spurium applied by the UASS with a spraying volume of 22.5–60 L ha−1, according to fresh weights of aboveground parts at 45 d after treatment; however, this was not the case for the control of Stellaria aquatica. The POST herbicides showed the highest control efficacy against S. aquatica when applied with UASS at a spraying volume of 60 L ha−1 and the double-spraying technique. Similarly, another formulation of POST herbicides (15.75 g·ai·ha−1 mesosulfuron-methyl + 60 g·ai·ha−1 pinoxaden) showed similar control efficacies with manual spraying against Beckmannia syzigachne, applied by the UASS with a spraying volume of 45 or 60 L ha−1, using the double-spraying strategy. Conclusion: Applying PRE or POST wheat herbicides with an UASS, double-spraying routed in length and breadth with a spraying volume of 45–60 L ha−1 should be recommended.

Effect of Allelopathy from Methanolic Extract of Broadleaf Weeds (Ageratum conyzoides and Borreria alata) on the Viability of Soybean Seeds (Glycine max L.)

The experiment aimed to investigate the allelopathic effects of active compounds present in broadleaf weeds Ageratum conyzoides and Borreria alata. The study also sought to assess the viability of various seed varieties grown using allelopathic extracts from these weeds, varying in concentrations of tannins and phenols. The research findings revealed that methanol extracts exhibited potent allelopathic properties, inhibiting germination, radicle and hypocotyl growth, as well as reducing the germination rate of soybean seeds. B. alata weed extracts demonstrated lower allelopathy than A. conyzoides, suggesting a possible alteration in the active compounds (allelochemicals) present due to a reforming process. Extracts from both A. conyzoides and B. alata weeds inhibited root length, hypocotyl growth, and germination across a range of concentrations, from low (10% v/v) to high (30% v/v).