Weed Species Research Articles

Development and evaluation of a machine vision and deep learning-based smart sprayer system for site-specific weed management in row crops: An edge computing approach

Traditional weed management often involves blanket herbicide spraying, resulting in substantial herbicide wastage, environmental concerns, and herbicide resistant issues. Smart spraying systems utilizing robotics and sensors technologies can minimize herbicide usage and provide a sustainable solution for site-specific weed management. A machine vision-based spraying system was designed and developed for weed identification and precise spray application onto the target weeds. The sprayer platform utilizes a deep learning YOLOv4 model to accurately recognize multiple weed species, facilitating targeted spray application. The platform is equipped with an FLIR RGB camera for real-time image acquisition and Nvidia Jetson AGX Orin edge device for deploying weed detection deep-learning model. The GPIO pins of Nvidia Jetson were utilized to activate relay, providing precise on/off control over the TeeJet solenoid valves for spot spraying. Both indoor and field experiments were conducted to evaluate and compare the performance of vision-based sprayer system for weed identification and precise spraying onto the target weeds. In the indoor experiment, the sprayer system showed the average effective spraying rate of 93.33 %, with the precision of 100 % and recall of 92.8 %. Conversely, the field experiment resulted in a slightly lower average effective spraying rate of 90.6 %, while maintaining a precision of 95.5 % and a recall of 89.47 %. The reduced accuracy of the spraying system in field experiment was due to varying outdoor conditions such as lighting, shadows, and wind velocity. Overall, the result of this study demonstrates the spraying system's potential for targeted herbicide application onto the grid cells containing weeds, effectively reducing herbicide usage and overall weed management costs.

Evaluation of the potentiality of diverse weed species in mobilising soil bioavailable phosphorus

The present study was carried out to assess the inorganic phosphorus (P)- dynamics under the rhizosphere of 10 weed species belonging to 8 different families. A fractionation study revealed that sol-P and Ca2-P were highest in M. denticulata L. and C. rotundus L. with 67.25 mg kg-1 and 48.37 mg kg-1, respectively (p<0.05) which could be attributed to high alkaline phosphatase activity in the rhizosphere. Out of the selected weed species, labile-P: nonlabile- P content was highest in M. denticulata L. (0.42) which is 38% higher than C. arvensis L. In terms of biomass and leaf P (%) C. didymus (L.) Sm. recoreded highest but, interestingly M. denticulata L. though had a higher sol-P but failed to translocate P-to the above and below-ground parts. Hence, M. denticulata L. being legume was an excellent mobilizer of non-labile P and can improve the available P for the subsequent crop.

Understanding the dynamics of Meloidogyne incognita infestation in pomegranate orchards of Himachal Pradesh, India (year 2018, 2019 and 2021) and its management strategies

This study investigates the prevalence and dynamics of pomegranate wilt disease induced by Meloidogyne incognita across the Kullu, Mandi and Solan districts of Himachal Pradesh (India), revealed notable spatial and temporal variations in nematode populations and galling severity across the regions. The highest average nematode infestation of 9.25 % was observed at Nauni with highest counts of average second-stage juvenile (J2) larvae (449 larvae per 100 cc of soil) followed by Hurla (Kullu) with 7.42 % infestation. Correlation analysis reveals a strong positive relationship between larval population and galling severity suggesting a potential link between nematode levels and plant damage. Common disease symptoms were leaf size reduction, yellowing and gradual decline of pomegranate plants, often observed in patches within orchards. Microscopic identification revealed distinctive pear-shaped body of mature females while J2 larvae displayed vermiform shapes and the associated species of M. incognita was confirmed through examination of the perineal pattern. Pathogenicity test reveals initiation of leaf yellowing symptom after 45 days of inoculation of larval suspension and root galling was observed after 60 days onward followed by plant decline under greenhouse conditions. Results from pot and field experiments demonstrated the efficacy of Fluopyram and Fluensulfone in reducing nematode populations and galling severity. Treatment with drenching of Fluopyram at the rate of 2 ml/L reduced 98.56 % larvae under field and 99.00 % larvae/100 cc soil under pot conditions. Statistical analysis (paired t-test and MANOVA) confirms significant differences in galling severity and larval population before and after drenching. The study also underscores the importance of weed management in disease mitigation as several weed species (Chenopodium album and Solanum nigrum) were identified as potential reservoirs for M. incognita in infested pomegranate plant basin. This investigation contributes to the advancement of management practices for pomegranate cultivation that addresses both nematode and weed infestations ultimately enhancing crop resilience and productivity.

The influence of temperature, light, pH and salinity on germination and growth of Cutandia memphitica (Spreng.) Benth

Background: There are many weed species that affect yield and quality in date palm orchards. Cutandia memphitica (Spreng.) Benth. is one of the weeds that is common in date palm orchards in Iraq. However, there is not enough information about C. memphitica in the literature. In order to provide information about the effect of key environmental factors (temperature, light, pH, and salt) on the seed biology of this weed species, this study was conducted.Methods: Within 2020, seeds were collected from agricultural regions in southern Iraq, and trials were done at Erciyes University Faculty of Agriculture labs in Kayseri Türkiye. All experiments were carried out with 30 seeds in the sterile 90 mm (90×15) petri dishes containing two layers of sterile filter paper.Results: The results of this investigation revealed that the seeds of this species germinated by 72.49% in three days when incubated at 25°C, and by 96.66% in 14 days when incubated at 15°C. The results also indicated that even during the longest incubation time examined, which was 28 days, the seeds of this species never germinated at 30 degrees or above. They can germinate during this period if kept at 5°C. The study also revealed that 90% of the seeds of this species germinated in complete darkness, whereas only 11.66% germinated in light. However, light has a significant impact on studied growth parameters (plant height and seedling fresh and dry weight). The results also demonstrate that the pH levels examined, which varied from 4 to 10, had no effect on the seed germination and growth parameters of seedling.Conclusion: The results showed that the seeds of this species germinated at the highest salinity levels (250 mM NaCl) by 10.83%. Meanwhile, the best germination was recorded at 25 mM salinity level of 89.16%, but without significant differences with salinity level at 50 mM and control. Also, the growth indicators were reduced significantly at the salinity level of 250 mM compared to the control.Keywords: Light; Salinity; Seed Germination; Temperature; Weed; Date Palm

An investigation of the pigments, antioxidants and free radical scavenging potential of twenty medicinal weeds found in the southern part of Bangladesh.

Despite their overlooked status, weeds are increasingly recognized for their therapeutic value, aligning with historical reliance on plants for medicine and nutrition. This study investigates the medicinal potential of native weed species in Bangladesh, specifically pigments, antioxidants, and free radical scavenging abilities. Twenty different medicinal weed species were collected from the vicinity of Khulna Agricultural University and processed in the Crop Botany Department Laboratory. Pigment levels were determined using spectrophotometer analysis, and phenolics, flavonoids, and DPPH were quantified accordingly. Chlorophyll levels in leaves ranged from 216.70 ±9.41 to 371.14 ±28.67 µg g-1 FW, and in stems from 51.98 ±3.21 to 315.89 ±17.19 µg g-1 FW. Flavonoid content also varied widely, from 1,624.62 ±102.03 to 410.00 ±115.58 mg CE 100 g-1 FW in leaves, and from 653.08 ±32.42 to 80.00 ±18.86 mg CE 100 g-1 FW in stems. In case of phenolics content Euphorbia hirta L. displaying the highest total phenolic content in leaves (1,722.33 ±417.89 mg GAE 100 g-1 FW) and Ruellia tuberosa L. in stems (977.70 ±145.58 mg GAE 100 g-1 FW). The lowest DPPH 2.505 ±1.028 mg mL-1was found in Heliotropium indicum L. leaves. Hierarchical clustering links species with pigment, phenolic/flavonoid content, and antioxidant activity. PCA, involving 20 species and seven traits, explained 70.07% variability, with significant PC1 (14.82%) and PC2 (55.25%). Leaves were shown to be superior, and high-performing plants such as E. hirta and H. indicum stood out for their chemical composition and antioxidant activity. Thus, this research emphasizes the value of efficient selection while concentrating on the therapeutic potential of native weed species.

Curculionoidea (Insecta: Coleoptera) Species Detected on Some Weeds in Kahramanmaraş Province, Türkiye Part I

This study was conducted to determine the Curculionoidea species on weeds found in non-agricultural areas in Kahramanmaraş Province between 2021 and 2022, weekly from late March early April until the end of September after the weeds begin to germinate, and at fifteen-day intervals when the weeds start to dry towards the end of September. Studies were carried out. As a result of this study two genera belonging to the family Curculionidae, Lixinae Schoenherr, 1823 subfamily of the superfamily Curculionoidea, and fourteen species belonging to these genera. Larinus cinerascens Capiomont, 1874, one of the identified species, is a new record for the Curculionoidea fauna of Türkiye. A total of five species, including Lixus algirus L., Lixus vilis (Rossi, 1790), Larinus cinerascens Capiomont, 1874, Larinus hedenborgi Boheman, 1845, Larinus turbinatus Gyllenhal, 1835, are new records for Kahramanmaraş Province. In addition, twelve weed species were identified as new host plants for the identified Curculionoidea species.

The Effect of Climate on Strongly Disturbed Vegetation of Bait Sites in a Central European Lower Montane Zone, Hungary

Human landscape-transforming activities contribute to the global change in vegetation in different forms. Hunting is one of the most ancient human landscape-shaping activities. Feeders for hunting are particularly disruptive to vegetation. In the present study, we conducted a vegetation survey in these highly disturbed places. We investigated the vegetation dynamics over several years in the turkey oak–sessile oak zone, in two areas with different moisture and shade conditions (forest and clearing). Important background factors are the changes in precipitation and temperature. Our results confirm that weed infestation is detectable at bait sites over a long period. The seasonal changes in field weed vegetation, as well as the increase in the number and coverage of weed species at the end of summer, resulting from lifestyle characteristics, were generally detectable in all years and locations, especially in the case of open and more strongly degraded clearings. Meteorological factors played a role in the degree of weed infestation in each year. Degradation was more significant in drought years, while regeneration was also observed in wetter periods. At baits located in the clearing, we showed a positive correlation between the amount of summer precipitation and the total coverage of weed species, as well as between the average spring temperature and the coverage of certain weed species. With the drying of the climate, the disturbed areas are constantly losing their natural value, but wetter weather is not an automatic solution either. Considering that there are approx. 30,000 bait sites in the country, and they are used regularly and very intensively, they can serve as major infection hotspots for alien species in a network.

Eryngial: An α,β-Unsaturated Fatty Aldehyde as the Major Phytotoxin in Spiny Coriander (Eryngium foetidum L.) Essential Oil.

Weed species many times possess allelochemicals as a part of their survival strategy. These metabolites can be potential targets in search of natural phytotoxins. This study aims to evaluate the phytotoxic ability of fatty aldehyde-rich essential oil from spiny coriander (Eryngium foetidum) leaves, also known as fitweed or spiritweed and to further identify the active phytotoxins. This oil dose-dependently inhibited the wheatgrass coleoptile and radicle growth in multiple bioassays with half maximal inhibitory concentration (IC50) 30.6-56.7 μg/mL, while exhibiting a less pronounced effect on the germination (IC50 181.8 μg/mL). The phytotoxicity assessment of two oil constituents identified eryngial (trans-2-dodecenal), exclusively major fatty aldehydic constituent as the potent growth inhibitor with IC50 in the range 20.8-36.2 μg/mL during an early phase of wheatgrass emergence. Eryngial-inspired screening of eleven saturated fatty aldehydes and alcohols did not find a significantly higher phytotoxic potency. In an open vessel, eryngial as the supplementation in agar medium, dose-dependently inhibited the growth of pre-germinated seeds of one monocot (bermudagrass) and one dicot (green amaranth) weed species with IC50 in the range 23.8-65.4 μg/mL. The current study identified eryngial, an α,β-unsaturated fatty aldehyde of coriander origin to be a promising phytotoxic candidate for weed control.

Identifying rice field weeds from unmanned aerial vehicle remote sensing imagery using deep learning

BackgroundRice field weed object detection can provide key information on weed species and locations for precise spraying, which is of great significance in actual agricultural production. However, facing the complex and changing real farm environments, traditional object detection methods still have difficulties in identifying small-sized, occluded and densely distributed weed instances. To address these problems, this paper proposes a multi-scale feature enhanced DETR network, named RMS-DETR. By adding multi-scale feature extraction branches on top of DETR, this model fully utilizes the information from different semantic feature layers to improve recognition capability for rice field weeds in real-world scenarios.MethodsIntroducing multi-scale feature layers on the basis of the DETR model, we conduct a differentiated design for different semantic feature layers. The high-level semantic feature layer adopts Transformer structure to extract contextual information between barnyard grass and rice plants. The low-level semantic feature layer uses CNN structure to extract local detail features of barnyard grass. Introducing multi-scale feature layers inevitably leads to increased model computation, thus lowering model inference speed. Therefore, we employ a new type of Pconv (Partial convolution) to replace traditional standard convolutions in the model.ResultsCompared to the original DETR model, our proposed RMS-DETR model achieved an average recognition accuracy improvement of 3.6% and 4.4% on our constructed rice field weeds dataset and the DOTA public dataset, respectively. The average recognition accuracies reached 0.792 and 0.851, respectively. The RMS-DETR model size is 40.8 M with inference time of 0.0081 s. Compared with three classical DETR models (Deformable DETR, Anchor DETR and DAB-DETR), the RMS-DETR model respectively improved average precision by 2.1%, 4.9% and 2.4%.DiscussionThis model is capable of accurately identifying rice field weeds in complex real-world scenarios, thus providing key technical support for precision spraying and management of variable-rate spraying systems.

A 4-year field study monitoring the evolution of Trp574Leu-resistant plants in an Echinochloa crus-galli population under different crop rotation and herbicide programs in maize.

A 4-year experiment evaluated the effects of different integrated weed management (IWM) programs on the evolution of a Echinochloa crus-galli population resistant to acetolactate synthase (ALS) inhibitors in a maize cropping system. The programs included the continued use of ALS inhibitors, mixing them with alternative herbicides, or without ALS-inhibitors, in all cases under maize monocrop or a biennial crop rotation. IWM programs that relied solely on non-ALS-inhibitors usually achieved high control levels across years (> 90%). Additionally, Trp574Leu-resistant plants became prevalent (> 90%) in programs only using ALS inhibitors, while in the rest the frequency of susceptible plants did not substantially decrease below 40%. Regarding the other monitored grass weeds, Digitaria sanguinalis and Panicum dichotomiflorum were effectively controlled in programs using ALS-inhibitors without soybean rotation or in programs without ALS-inhibitors altogether, excepting the program relying on an 4-hydroxyphenylpyruvate dioxygenase (HPPD)-inhibitor under maize monocrop for the latter species (0%). At the end of the experiment, the only IWM programs that reduced infestation levels were the one without ALS-inhibitors under soybean rotation, and the one with standard pre-emergence treatments. These findings highlight the effectiveness of crop rotation and alternative herbicides both pre- or post-emergence in controlling E. crus-galli. ALS-inhibitors, while challenged by resistance in E. crus-galli, remain valuable tools for managing other grass weed species in maize. It is crucial to adapt IWM strategies for herbicide-resistant E. crus-galli and other grass weed populations to mitigate the further evolution of resistance. © 2024 Corteva Agriscience. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Comprehensive analysis and implications of Veronica persica germination and growth traits in their invasion ecology

Invasive alien species implications in ecological threats are attributed to their unique characteristics that are linked to their invasion. Veronica persica (Plantaginaceae family) is an alien weed species in Egypt. Regardless of its widespread globally in various regions, the growth traits and behavior of V. persica remain poorly understood. The comprehensive analysis, reveals the optimal germination (Gmax) was detected at 10/20 °C, 15/20 °C, and 20/25 °C at the moderate temperature regimes. The rapid germination rate (G rate) peaked at 10/20 °C regime, with a rate of 0.376 per day. Furthermore, under stress conditions, V. persica has 50% germination inhibition (G50) and 50% of growth inhibition occurred at − 0.91 MPa and 0.75 MPa of osmotic pressure and 3225.81 ppm and 2677.1 ppm of salt stress (NaCl) respectively. The germination ranged from 6 to 9 pH, with the highest germination percentage occurring at a pH of 7 & 8, reaching 88.75% compared to the control group. There is a strong interaction effect between habitats and plant stages, the plant stages and habitats have significant effects (p ≤ 0.00) on V. persica growth. There was high and moderate plasticity in the response of morphological and growth features between stages. During the seedling-juvenile interval and the juvenile-flowering stages, respectively, there was a noticeable increase in both Relative Growth Rate and Net Assimilation Rate. Demographic surveys identified approximately 24 species across 11 families associated with V. persica in invaded areas. The Sorenson indices of qualitative index exhibited high similarity values in the invaded sites by (82.35%) compared to (72.72%) in non-invaded sites. However, interactions with native communities were reflected in lower richness, diversity, and evenness, displaying slightly higher Simpson index 1 (λ) values compared to invaded and non-invaded sites (0.043 and 0.0290) vs. (0.0207 and 0.268), in rangelands and F. carica orchards respectively. These results emphasize the substantially higher adaptability of V. persica to variable environmental conditions and abilities to invade a new community. This knowledge about invasive V. persica weeds germination and growth is itemized as the consistent predictive base for future invasion and informs strategic management priorities.

Molecular Mechanisms of Resistance against PSII-Inhibiting Herbicides in Amaranthus retroflexus from the Czech Republic.

Amaranthus retroflexus L. (redroot pigweed) is one of the most problematic weeds in maize, sugar beet, vegetables, and soybean crop fields in Europe. Two pigweed amaranth biotypes (R1 and R2) from the Czech Republic resistant to photosystem II (PSII)-inhibiting herbicides were analyzed in this study. This study aimed to identify the genetic mechanisms that underlie the resistance observed in the biotypes. Additionally, we also intended to establish the use of chlorophyll fluorescence measurement as a rapid and reliable method for confirming herbicide resistance in this weed species. Both biotypes analyzed showed high resistance factors in a dose-response study and were thus confirmed to be resistant to PSII-inhibiting herbicides. A sequence analysis of the D1 protein revealed a well-known Ser-Gly substitution at amino acid position 264 in both biotypes. Molecular docking studies, along with the wild-type and mutant D1 protein's secondary structure analyses, revealed that the S264G mutation did not reduce herbicide affinity but instead indirectly affected the interaction between the target protein and the herbicides. The current study identified the S264G mutation as being responsible for conferring herbicide resistance in the pigweed amaranth biotypes. These findings can provide a strong basis for future studies that might use protein structure and mutation-based approaches to gain further insights into the detailed mechanisms of resistance in this weed species. In many individuals from both biotypes, resistance at a very early stage (BBCH10) of plants was demonstrated several hours after the application of the active ingredients by the chlorophyll fluorescence method. The effective PS II quantum yield parameter can be used as a rapid diagnostic tool for distinguishing between sensitive and resistant plants on an individual level. This method can be useful for identifying herbicide-resistant weed biotypes in the field, which can help farmers and weed management practitioners develop more effective weed control tactics.

Understanding the responses of tillering to 2,4-D isooctyl ester in Setaria viridis L.

BackgroundGreen foxtail [Setaria viridis (L.)] is one of the most abundant and troublesome annual grass weeds in alfalfa fields in Northeast China. Synthetic auxin herbicide is widely used in agriculture, while how auxin herbicide affects tillering on perennial grass weeds is still unclear. A greenhouse experiment was conducted to examine the effects of auxin herbicide 2,4-D on green foxtail growth, especially on tillers.ResultsIn the study, 2,4-D isooctyl ester was used. There was an inhibition of plant height and fresh weight on green foxtail after application. The photosynthetic rate of the leaves was dramatically reduced and there was an accumulation of malondialdehyde (MDA) content. Moreover, applying 2,4-D isooctyl ester significantly reduced the tillering buds at rates between 2100 and 8400 ga. i. /ha. Transcriptome results showed that applying 2,4-D isooctyl ester on leaves affected the phytohormone signal transduction pathways in plant tillers. Among them, there were significant effects on auxin, cytokinin, abscisic acid (ABA), gibberellin (GA), and brassinosteroid signaling. Indeed, external ABA and GA on leaves also limited tillering in green foxtail.ConclusionsThese data will be helpful to further understand the responses of green foxtail to 2, 4-D isooctyl ester, which may provide a unique perspective for the development and identification of new target compounds that are effective against this weed species.

Screening the Potential f Fungal Derived Bioherbicide in Weed Management

Synthetic herbicides have long been a cornerstone of modern agriculture, providing effective weed control but often at significant environmental and health costs. These chemicals can persist in the environment, leach into groundwater, and harm non-target organisms, including humans. Additionally, the overuse of synthetic herbicides has led to the development of herbicide-resistant weeds, further complicating weed management strategies. In response to these challenges, researchers and farmers alike are increasingly turning to bioherbicides derived from fungi as a sustainable alternative. Fungal bioherbicides harness the natural antagonistic properties of fungi to target weeds. Unlike synthetic herbicides, which are chemically synthesized and often broad-spectrum in action, fungal bioherbicides utilize either the fungi themselves as pathogens or their metabolites to disrupt weed growth. This approach offers several distinct advantages:Target Specificity: Fungal bioherbicides can be highly specific to certain weed species or even to specific stages of weed growth. This specificity reduces collateral damage to non-target plants and organisms, making them particularly suitable for environmentally sensitive areas such as organic farms, riparian zones, and protected ecosystems. Environmental Friendliness: Unlike synthetic herbicides that can persist in the environment and accumulate in soil and water bodies, fungal bioherbicides generally have lower persistence. They degrade more rapidly and often have minimal impact on non-target organisms, thereby preserving biodiversity and ecosystem health. Reduced Risk of Resistance: Synthetic herbicides often face the challenge of herbicide-resistant weeds, which evolve due to continuous and widespread use. Fungal bioherbicides, by contrast, pose a lower risk of resistance development. This is because they typically act through multiple modes of action or biochemical pathways within the weed, making it harder for weeds to develop resistance mechanisms. Research into fungal-derived bioherbicides is actively exploring and harnessing these advantages. Scientists are screening diverse fungal species to identify potent pathogens or metabolites that effectively inhibit weed growth. Moreover, advances in biotechnology and genetic engineering allow for the enhancement of fungal strains to optimize their bioherbicidal properties while ensuring safety and efficacy. One promising example is the use of fungal pathogens like Phomamacrostoma and Colletotrichum truncatum, which have demonstrated efficacy against various weed species including common agricultural weeds like velvetleaf and pigweed. These fungi infect weeds through mechanisms such as spore attachment, penetration of plant tissues, and secretion of phytotoxic metabolites that inhibit weed growth. In addition to their direct impact on weed management, fungal bioherbicides contribute to sustainable agricultural practices by reducing reliance on synthetic chemicals. They align with principles of integrated pest management (IPM) by offering a biological control method that complements cultural and mechanical weed control strategies. Moving forward, continued research and development efforts are essential to refine fungal bioherbicides, optimize application techniques, and expand their practical use in diverse agricultural settings. Challenges such as formulation stability, cost-effectiveness, and regulatory approvals also need to be addressed to facilitate widespread adoption by farmers.

Environmental factors determining weed species distribution in organic manure and inorganic fertiliser smallholder maize (Zea mays L.) production

AbstractWeeds are a major concern in crop production, and their environmental plasticity hinders successful control. A phytosociological study assessed weed distribution patterns in smallholder maize (Zea mays L.) production under different climatic and soil factors in the 2020/2021 and 2021/2022 cropping seasons. Thirty‐six maize fields from the Highveld (Mankayane) and the Middleveld (Luve) of Eswatini, were investigated with three fertiliser regimes applied (cattle manure only, cattle manure plus inorganic fertiliser and inorganic fertiliser only). Phytosociological attributes of weed species including density were collected using a 25 m transect placed horizontally at the centre of each field. Climatic factors and soil physiochemical properties considered included altitude, rainfall, temperature, soil texture, soil pH, nitrogen, phosphorus, potassium, calcium, magnesium, copper, iron, zinc and manganese. Fifty‐six weed species belonging to 16 families were recorded. Distance‐based multivariate multiple regression (DistLM) analysis was used to determine the relationship between weed species composition as the dependent variable from the fertiliser regimes and the environmental factors as the independent variable. Eight environmental variables explained 25% variation in species distribution namely; altitude, temperature, nitrogen, phosphorus, potassium, copper, magnesium and percentage silt. At Luve, temperature, copper and magnesium significantly explained weed distribution in all three fertiliser regimes, while phosphorus influenced weed distribution in the manure only regime. At Mankayane, nitrogen affected weed distribution in the manure plus inorganic fertiliser and inorganic fertiliser regimes whereas altitude, phosphorus, potassium, and %silt influenced weed distribution in the manure only and manure plus inorganic fertiliser regimes. The observations suggest that some weed species coexist between fertiliser regimes and study areas while others occur in specific environments only.

Emergence Pattern of Argemone mexicana, Brassica tournefortii, and Rapistrum rugosum in Eastern Australia

A study assessed the potential for using cumulative growing degree days (CGDD) to predict the weed emergence periodicity of three weed species: Argemone mexicana, Brassica tournefortii, and Rapistrum rugosum. Weed emergence was monitored regularly by placing 200 fresh seeds of each weed species on the soil surface. Weed emergence data was fit using a three-parameter sigmoidal Gompertz model. The CGDD required for 50% emergence of A. mexicana ranged from 3380 to 5302, depending upon the seasonal variation in temperature and rainfall. The majority of emergence appeared from March to June. The seeds of A. mexicana exhibited dormancy, as the majority of seeds germinated in the second season. The CGDD required for 50% emergence of B. tournefortii ranged from 824 to 2311, depending upon the seasonal variation in temperature and intensity of rainfall. Most cohorts of B. tournefortii appeared in the first season from February to June, indicating little dormancy in seeds. The CGDD required for 50% emergence of R. rugosum ranged from 2242 to 2699, depending upon weather parameters (temperature and rainfall). The main cohorts of R. rugosum appeared from February to June, and 60% of seeds germinated in the first season, while 40% germinated in the second season, indicating dormancy in seeds. The coefficients of determination for the model verification on the emergence pattern of three weeds were > 85%, suggesting that CGDD are good predictors for the emergence of these weeds. These results suggest that forecasting the emergence of three weed species on the basis of CGDD and rainfall patterns will help growers to make better weed management decisions.

Multilocus sequence analysis of ‘Candidatus Phytoplasma asteris’ associated with phyllody of cucumber in India and development of loop‐mediated isothermal amplification (LAMP) assay for its detection

A survey assessed cucumber phyllody disease incidence in Chikkaballapura, Bengaluru Rural, Bengaluru Urban, and Bagalkote districts of Karnataka, India. The average disease incidence ranged from 8 to 18 %. A total of 9 samples showing phyllody and little leaf symptoms were collected and association of phytoplasma was confirmed through 16S rRNA gene amplification, using universal primer pair P1/P7, and followed by nested PCR using primer R16F2n/R16R2. Further, characterization through multilocus sequence analysis targeting secY and rpl22 genes confirmed all nine strains as part of the 16SrI group ('Candidatus Phytoplasma asteris'). Additionally, four weed species (Lecusa aspera, Parthenium hysterophorus, Acaranthus sp., and Amaranthus viridis) found in cucumber fields tested positive for phytoplasma (16SrI) disease. In-silico RFLP analysis of the amplified F2n/R2 region of the 16S rRNA gene indicated that two phytoplasma strains (CuPP1 and CuPP3) from Chikkaballapura belonged to subgroup X (16SrI-X), one phytoplasma strain (CuPP2) belonged to subgroup B (16SrI–B). While the remaining strains from Bangalore Urban, Bengaluru Rural, and Bagalkote districts belonged to subgroup B (16SrI–B). A loop-mediated isothermal amplification (LAMP) detection protocol was also developed for 'Ca P. asteris', targeting the phytoplasma 16S ribosomal DNA. Comparison of assay sensitives demonstrated that LAMP technique is highly efficient and could detect the presence of phytoplasma up to 50 fg of template DNA. LAMP-based detection offers superior ease of use, cost-effectiveness, and rapid results. To the best of our knowledge, this is the first report of phytoplasma causing phyllody disease in cucumber crop in India.

Optimizing molecular assays for glyphosate and ALS-inhibitor resistance diagnostics in four weed species

Herbicide-resistant weeds pose a threat to food production in modern agriculture, causing US$32 billion in crop production losses worldwide. In Michigan, highly troublesome and widespread weeds include waterhemp, Palmer amaranth, common ragweed, and horseweed, with accessions that are resistant to glyphosate (Group 9) and ALS-inhibitors (Group 2), major herbicide sites of action utilized in soybean and corn cropping systems. Molecular assays for rapid resistance diagnostics to confirm the in-field status of herbicide resistance can assist with more effective, timely, and proactive management. In this research, we developed and tested PCR-based assays to identify target site resistance mechanisms to both herbicide groups through Sanger sequencing and EPSPS copy number variation. Nine different SNPs were identified in five ALS positions known to confer herbicide resistance among all species surveyed. Pro197Ser was the most frequent in horseweed and common ragweed accessions, whereas Trp574Leu was the predominant mutation in Palmer amaranth and waterhemp. Four horseweed accessions contained the Pro106Ser mutation in the EPSPS gene, which confers resistance to glyphosate. Additionally, waterhemp and Palmer amaranth had 2–7 and 20–160 copies of EPSPS, respectively. The assays were validated by comparing genotyping of several field-collected accessions of unknown resistance status with known resistant and susceptible accessions. The efficacy of genotyping assays was >98% and required only two days, confirming that molecular assays are a robust tool for rapid resistance diagnostics. These assays can help growers evaluate herbicide resistance status in weed populations within the same growing season, allowing them to adopt effective management practices.

Pollinator activity and flowering in agricultural weeds in Sweden.

The extent to which weeds in arable land are useful to pollinators depends in part on the temporal pattern of flowering and insect flight activity. We compiled citizen science data on 54 bees and hoverflies typical of agricultural areas in southern Sweden, as well as 24 flowering weed species classified as pollinator-friendly in the sense that they provide nectar and/or pollen to pollinators. The flight periods of the bees and hoverflies varied greatly, but there were also some consistent differences between the four groups studied. The first group to fly were the early flying solitary bees (7 species), followed by the social bees (18 species). In contrast, other solitary bees (11 species) and hoverflies (22 species) flew later in the summer. Solitary bees had the shortest flight periods, while social bees and hoverflies had longer flight periods. Flowering of weed species also varied greatly between species, with weeds classified as winter annuals (e.g., germinating in autumn) starting early together with germination generalists (species that can germinate in both autumn and spring). Summer annuals (spring germinators) and perennials started flowering about a month later. Germination generalists had a much longer flowering period than the others. Weekly pollinator records were in most cases significantly explained by weed records. Apart from early flying solitary bees, all models showed strong positive relationships. The overall best explanatory variable was the total number of weeds, with a weight assigned to each species based on its potential as a nectar/pollen source. This suggests that agricultural weeds in Sweden provide a continuous potential supply of nectar and pollen throughout the flight season of most pollinators.

Effect of Aqueous Extract of Ageratum Houstonianum on Seed Germination and Seedling Growth of Triticum Aestivum (Wheat)

Invasive plants are species that do not belong in a particular habitat but enter and establish themselves there. They are known for their adaptability and competitiveness in different environmental conditions. They tend to compete with crops for crucial resources, including water, light, and nutrients and can hinder crop growth and development through allelopathy. The aim of the current research was to investigate the allelopathic effect of aqueous extracts of Ageratum houstonianum on the germination and growth of wheat (Triticum aestivum) seedlings. The aqueous extracts were obtained from the leaves of A. houstonianum at various concentrations, including control, 25%, 50%, and 100%, and applied to pot and petri-plates cultures. The experiment was set up with 5 replicates for both the Petri plates and pot cultures. The study results showed that A. houstonianum aqueous leaf extracts had a significant impact on the germination and growth of T.aestivum. The concentrated (100%) aqueous leaf extracts of A. houstonianum significantly hindered the germination of seeds and growth parameters of T. aestivum. Additionally, the extract treatments of the weed species resulted in changes in soil pH and soil fertility. When invasive weed species grow alongside crops in fields, they may consume a significant number of resources required for crop growth, leading to a decrease in both the quantity and quality of agricultural output. Hence, this study highlights the potential adverse effects of invasive weeds on crop growth and development, and how they can negatively impact agricultural productivity. Therefore, there is a need for effective management strategies to control the spread of invasive weed species and preserve the productivity of agricultural land.