Weed Seeds Research Articles

Seed germination ecology of Sumatran fleabane (Conyza sumatrensis) in relations to various environmental parameters

AbstractSumatran fleabane [Conyza sumatrensis (Retz.) Walker] is an emerging weed in the Australian cropping region. Populations resistant to glyphosate have evolved in Australia, creating the demand for information regarding the seed germination ecology of glyphosate-resistant (R) and glyphosate-susceptible (S) populations of C. sumatrensis. A study was conducted to examine the effects of temperature, light intensity, salt stress, osmotic stress, and burial depth on the germination and emergence of two populations (R and S) of C. sumatrensis. Both populations were able to germinate over a wide range of alternating day/night temperatures (15/5 to 35/25 C). In light/dark conditions, the R population had higher germination than the S population at 20/10 and 35/25 C. In the dark, the R population had higher germination than the S population at 25/15 C. In the dark, germination was inhibited at 30/20 C and above. Averaged over populations, seed germination of C. sumatrensis was reduced by 97% at zero light intensity (completely dark conditions) compared with full light intensity. Seed germination of C. sumatrensis was reduced by 17% and 85% at osmotic potentials of −0.4, and −0.8 MPa, respectively, compared with the control treatment. The R population had lower germination (57%) than the S population (72%) at a sodium chloride concentration of 80 mM. Seed germination was highest on the soil surface and emergence was reduced by 87% and 90% at burial depths of 0.5 and 1.0 cm, respectively. Knowledge gained from this study suggests that a shallow-tillage operation to bury weed seeds in conventional tillage systems and retention of high residue cover on the soil surface in zero-till systems may inhibit the germination of C. sumatrensis. This study also warrants that the R population may have a greater risk of invasion over a greater part of a year due to germination over a broader temperature range.

Ensiling Reduces Seed Viability: Implications for Weed Management

Ensiling, a lactic acid fermentation process, is mainly used to preserve biomass. In addition, it has been shown to affect seed viability of some plant species. The extent to which this makes ensiling suitable as a weed control measure, however, has not yet been determined. Both the range of controllable species and the parameters of an ensiling process that safely kills seeds are still undefined. We aimed to determine the effect of varying substrate and ensiling conditions on the seed viability of 10 species selected to represent a wide range of different seed traits. Five different types of silages were made from maize or mixtures of wildflower and maize biomass and ensiled in lab-scale silos for 8 months. The pure maize silages were prepared under conditions either ideal or suboptimal for ensiling forage. Seeds of important weeds (Chenopodium album, Abutilon theophrasti) and of species from a wildflower mixture suitable for ensiling and biogas production (Cichorium intybus, Daucus carota, Echium vulgare, Malva alcea, Malva sylvestris, Melilotus albus, Melilotus officinalis) were tested. Seed viability was determined using a combination of tetrazolium and germination tests. Ensiling reduced seed viability across all 10 species significantly. Seed-killing efficacies of ensiling, however, differed widely among the species studied, largely related to whether the species could produce hard (physically dormant) seeds. Seeds from species without hardseededness were completely inactivated by ensiling, while the seed-killing efficacies for hardseeded species ranged from 5 to 60%. Variation in ensiled substrate and ensiling conditions had no consistent effect on seed survival. We concluded that ensiling has the potential to sustainably reduce seed viability of a wide range of species and therefore should be adopted as a component of integrated weed management in organic agriculture.

Compost Functions as Effective Replacement for Peat-Based Potting Media in Organic Greenhouse Transplant Production

Commercial horticulture in many regions of the world depends upon Sphagnum peat as a potting-media substrate, but extracting peat has serious environmental consequences. Composts may be able to serve as effective substitutes for peat and offer potential environmental advantages. The suitability of compost as potting media depends upon the raw materials as well as processing methods used. This study includes two related experiments—one with beet (Beta vulgaris L.) and the other with tomato (Solanum lycopersicum L.)—aimed at assessing the potential viability of farm-produced, food-residuals compost as a replacement for peat-based potting media in the production of organic vegetable transplants. The experiments were conducted in 2021 on the Berea College Farm in Kentucky, USA, a USDA certified organic farm. The results indicated that potting media composed of 75% to 100% compost performed as well as fertilized, peat-based growing media for plant growth. Further, although weeds were present in the compost, weed pressure was not severe enough to adversely affect crop growth. Thus, sterilization of compost, which did eliminate weeds in the compost, was not deemed necessary for using the compost as a partial or complete potting medium. Compost pasteurization was also assessed but was ineffective in destroying weed seeds.

Train to Pakistan: A Saga of Unsalvaged Suffering

The torments of the colossal human tragedy of the partition of India and its aftermath are still being borne by the people of India in some way or the other. The fissured social and emotional spirit of the people is still not healed. The horrific scenes of partition still haunt the psyche of the Indians. Millions were massacred and those that were alive were like live corpses moving around. Their sufferings are unfathomed. They not only suffered physically but also mentally and emotionally. Khushwant Singh’s Train to Pakistan is a novel that unfolds all aspects of suffering and pain which were endured by the people at that time. Singh has been successful in communicating to his readers the tribulations of the partition days, the harrowing experiences, grossness, the madness and the bestial horrors.The displacement of people from one country to another became the root cause of the whole holocaust. The village which bustled with activity turned into a kenopsia. Singh’s rankling at the idea of partition can be perceived in the novel. In the novel, Singh has vehemently written about every aspect of the dreaded violence to which women were subjected. It is quite obvious from the conditions prevailing in India that this splitting of the country was a futile effort. It sowed the seeds of communal discord permanently. People are still suffering they have not fully recovered from this psychosomatic trauma. The seeds of harmful weeds that were sown by the partition are still being reaped by the Indians.

THE INFLUENCE OF DIFFERENT PURITY OF NATURAL ALFALFA SEEDS ON THE PROCESSING EFFICIENCY

This paper presents the results of the seed processing of ten lots of natural alfalfa seed with different purity (from 68.0% to 86.5%). The test was carried out at the seed processing center of the Institute for forage crops Kruševac-Serbia. Seed losses, processing output, seed yield and quality of the processed seed were investigated. It is important that the difference between the amounts of pure seed from laboratory assessment and the actual amount after processing, are low. The purity of natural alfalfa seed depends on the crop condition and the harvest process. In the seed processing of small-grained leguminous plants, the processing output of seed is directly dependent on the percentage of weed species and other species in the natural seed. Seeds of quarantine weeds of dodder and curly dock are a particularly big problem in alfalfa seeds. In the case of high-purity seeds with low quarantine weeds share, processing output are high. By the legal procedure on the seed quality, the content of pure seed, inert materials, weeds and other species in the processed seeds is defined. The efficiency of the alfalfa seed processing depends on the initial purity of the seed, as well as the applied technical and technological process of seed processing. Based on the obtained results, it is possible to optimally adjust and select the appropriate equipment for the processing of alfalfa seed, depending on the quantity and type of weeds and other ingredients in the natural alfalfa seeds.

Weed Occurrence in a Young Apple Orchard Mulched With Two Different Organic Materials

Abstract In this study, conducted at the Research Station of the Wrocław University of Environmental and Life Sciences, Poland, we sought to determine the communities of weed species and their temporal occurrence in a young apple orchard mulched with spent mushroom compost or Miscanthus straw applied to tree rows. A herbicide fallow treatment was used as a control. During the first year of application, both organic mulches protected against the germination of weed seeds stored within the soil. In subsequent years, however, annual weeds occurred in the mulched tree rows, the most aggressive of which was Chenopodium album L. Annual increases in population densities were noted over the 4 subsequent years of research, particularly in the rows receiving spent mushroom compost. Perennial species in the family Poaceae and genus Malva were present in soil receiving both organic mulches. Trifolium repens L. was the perennial weed most often noted in the Miscanthus mulch, whereas Taraxacum officinale Web. was more characteristic of the spent mushroom compost. Commencing from the spring of the third year following apple tree planting, weed infestation associated with the spent mushroom compost was similar to that observed in the herbicide fallow, thus necessitating three annual applications of herbicide to further maintain the orchard. The insufficient weed suppression obtained with this mulch precludes its recommendation as an effective weed management system. Although Miscanthus straw provided extended tree row protection from weed infestation, herbicide intervention was also required. Notably, however, despite the fact that Miscanthus straw provided conditions more favorable to tree growth, apple tree yields and fruit quality tended to be similar under the three investigated orchard soil management systems.

Effect of Clay, Soil Organic Matter, and Soil pH on Initial and Residual Weed Control with Flumioxazin

Greenhouse studies were conducted to evaluate the effects of soil organic matter content and soil pH on initial and residual weed control with flumioxazin by planting selected weed species in various lab-made and field soils. Initial control was determined by planting weed seeds into various lab-made and field soils treated with flumioxazin (71 g ha−1). Seeds of Echinochloa crus-galli (barnyard grass), Setaria faberi (giant foxtail), Amaranthus retroflexus (redroot pigweed), and Abutilon theophrasti (velvetleaf) were incorporated into the top 1.3 cm of each soil at a density of 100 seeds per pot, respectively. Emerged plants were counted and removed in both treated and non-treated pots two weeks after planting and each following week for six weeks. Flumioxazin control was evaluated by calculating percent emergence of weeds in treated soils compared to the emergence of weeds in non-treated soils. Clay content was not found to affect initial flumioxazin control of any tested weed species. Control of A. theophrasti, E. crus-galli, and S. faberi was reduced as soil organic matter content increased. The control of A. retroflexus was not affected by organic matter. Soil pH below 6 reduced flumioxazin control of A. theophrasti, and S. faberi but did not affect the control of A. retroflexus and E. crus-galli. Flumioxazin residual control was determined by planting selected weed species in various lab-made and field soils 0, 2, 4, 6, and 8 weeks after treatment. Eight weeks after treatment, flumioxazin gave 0% control of A. theophrasti and S. faberi in all soils tested. Control of A. retroflexus and Chenopodium album (common lambsquarters) was 100% for the duration of the experiment, except when soil organic matter content was greater than 3% or the soil pH 7. Eight weeks after treatment, 0% control was only observed for common A. retroflexus and C. album in organic soil (soil organic matter > 80%) or when soil pH was above 7. Control of A. theophrasti and S. faberi decreased as soil organic matter content and soil pH increased. Similar results were observed when comparing lab-made soils to field soils; however, differences in control were observed between lab-made organic matter soils and field organic matter soils. Results indicate that flumioxazin can provide control ranging from 75–100% for two to six weeks on common weed species.

ВПЛИВ СИСТЕМ ОСНОВНОГО ОБРОБІТКУ ҐРУНТУ ТА УДОБРЕННЯ ІЗ ВИКОРИСТАННЯМ ПОБІЧНОЇ ПРОДУКЦІЇ НА ЗАБУР’ЯНЕНІСТЬ КУЛЬТУР СІВОЗМІНИ

The results of research on the study of the influence of soil processing systems and fertilizer using co-product for sown clogs and the yield of agricultural plants in a short-growing crop rotation are given. The influence of soil processing systems and fertilizer using co-products for sown clogs and the yield of agricultural plants in a short-live crop rotation is investigated. It has been established that on dark gray soil use in crop rotation of unifituted soil treatment systems contributes to an increase in the level of sown clogging (barley of the corn on grain at 1.4–1.6, wheat winter of winter of winter in 1.4–1.8 times) Due to the accumulation of the main amount of weed seeds in the upper soil layer. The system of fertilizer with by-products at the beginning of the vegetation of plants stimulates the germination of weeds. On average, over the years of research, the abundance of weeds in cropping crops at the beginning of vegetation when using unifituted soil treatment systems was 213–362 pcs/m2, dismissal – 94–108 pcs/m2, and before harvesting was noted a decrease in clogging, respectively, 29–57 pcs/m2, 10–13 pcs/m2. The air-dry weight of the weeds of the highest was with surface soil processing using co-product fertilizer (81.3–85.4 g/m2) relatively with dumping soil treatment (21.7–23.3 g/m2). The highest grain grain of wheat winter – 6.91 and 6.50, corn – 11.47 and 11.74, barley of the yarn – 5.37 and 5.13 and the rape of winter – 3.08 and 3.19 t/ha received when Discalled by 20–22 cm and shallow 10–12 cm soil processing system. With a 6–8 cm surface, the yields of crops decreased by 1.45, 3.66, 1.69 and 0.31 t/ha correspond to plants. A significant reason for reducing plant yields in versions with unifituted soil treatment systems served as a clogging factor, because the level here was higher than when the soil processing.

Weed management using tillage, seed rate and bed planting in durum wheat (Triticum durum Desf.) under an organic agriculture system

Weed management is a major obstacle in conversion from conventional to organic agriculture system and objective of this study was to manage weeds in organically grown durum wheat. The treatment combinations of conventional tillage (CT) or deep tillage (DT) with 50% higher plant densities, zero tillage (ZT) with and without residues, straw mulching 6 t ha−1 and bed planting plus 25% higher plant density followed by hand pulling were evaluated for weed control in durum wheat in a two-year study. Tillage has differential effect on weed seed distribution and more than 60% of weed seeds was concentrated in 0-7.5 cm soil layer in CT and ZT whereas 50.9% of weed seeds were displaced to 15-30 cm soil layer in DT. Bed planting plus 25% higher plant density followed by hand pulling resulted in lowering of weed density and biomass by 61.2% and 58.9%, respectively at harvest. The maximum growth parameters, yield attributes and wheat grain yield were obtained under bed planting with 25% higher plant density and one hand pulling. Sowing of durum wheat on raised beds or ZT with residue retention may be used as an effective and economical weed management tool under organic agriculture systems.

Herbicide Resistance to Metsulfuron-Methyl in Rumex dentatus L. in North-West India and Its Management Perspectives for Sustainable Wheat Production

Herbicide resistance in weeds is a global threat to sustaining food security. In India, herbicide-resistant Phalaris minor was the major problem in wheat for more than two decades, but the continuous use of metsulfuron-methyl (an ALS inhibitor) to control broadleaf weeds has resulted in the evolution of ALS inhibitor-resistant Rumex dentatus L. This review summarizes the current scenario of herbicide resistance in R. dentatus, along with its ecology and management perspectives. Studies have provided valuable insights on the emergence pattern of R. dentatus under different environments in relation to tillage, cropping systems, nutrients, and irrigation. Moreover, R. dentatus has exhibited higher emergence under zero tillage, with high infestation levels in rice-wheat compared to other wheat-based cropping systems (sorghum-wheat). Alternative herbicides for the management of resistant R. dentatus include pendimethalin, 2,4-D, carfentrazone, isoproturon, and metribuzin. Although the pre-emergence application of pendimethalin is highly successful in suppressing R. dentatus, but its efficiency is questionable under lower field soil moisture and heavy residue load conditions. Nevertheless, the biological data may be utilized to control R. dentatus. Therefore, herbicide rotation with suitable spray techniques, collecting weed seeds at differential heights from wheat, crop rotation, alternate tillage practices, and straw retention are recommended for addressing the resistance issue in R. dentatus in North India conditions. Overall, we discuss the current state of herbicide resistance in R. dentatus, the agronomic factors affecting its population, its proliferation in specific cropping systems (rice-wheat), and management strategies for containing an infestation of a resistant population.

Modelling the long‐term impact of harvest weed seed control for species like Bromus diandrus and Hordeum spp. that shed a portion of seed prior to harvest

AbstractHarvest weed seed control (HWSC) is an increasingly popular integrated weed management tactic to catch, destroy or remove weed seeds at crop harvest. However, most weed species shed some seed prior to crop harvest, and we have little data on the value of HWSC for those species with high or variable rates of seed shedding. In the current study, Bromus diandrus and Hordeum spp. were identified as problematic weeds with variable rates of seed shedding. Field data on B. diandrus and Hordeum spp. density, seed production and resulting crop yield were used to validate the output of a decision support tool: the Weed Seed Wizard. The tool was then used to generate a six‐year crop rotation scenario for each weed species. The level of annual HWSC in the scenario was set at 1%, 20%, 40%, 60%, 80% and 100% seed removal. The results indicated that B. diandrus in particular was difficult to control with herbicide alone and a conventional harvest (1% weed seed removed as a contaminant of the grain). By comparison, the total weed seed bank in the soil at the end of six years could be reduced by 46% using HWSC to annually destroy 20% of seed at crop harvest. Hordeum spp. were easier to control with herbicide, but HWSC still changed final seed density in the soil seed bank. Therefore, HWSC may be an effective management tactic for those weed species with early seed shedding, but this needs to be confirmed with field based research.

Seed Shattering: A Trait of Evolutionary Importance in Plants.

Seed shattering refers to the natural shedding of seeds when they ripe, a phenomenon typically observed in wild and weedy plant species. The timing and extent of this phenomenon varies considerably among plant species. Seed shattering is primarily a genetically controlled trait; however, it is significantly influenced by environmental conditions, management practices and their interactions, especially in agro-ecosystems. This trait is undesirable in domesticated crops where consistent efforts have been made to minimize it through conventional and molecular breeding approaches. However, this evolutionary trait serves as an important fitness and survival mechanism for most weeds that utilize it to ensure efficient dispersal of their seeds, paving the way for persistent soil seedbank development and sustained future populations. Weeds have continuously evolved variations in seed shattering as an adaptation under changing management regimes. High seed retention is common in many cropping weeds where weed maturity coincides with crop harvest, facilitating seed dispersal through harvesting operations, though some weeds have notoriously high seed shattering before crop harvest. However, high seed retention in some of the most problematic agricultural weed species such as annual ryegrass (Lolium rigidum), wild radish (Raphanus raphanistrum), and weedy amaranths (Amaranthus spp.) provides an opportunity to implement innovative weed management approaches such as harvest weed seed control, which aims at capturing and destroying weed seeds retained at crop harvest. The integration of such management options with other practices is important to avoid the rapid evolution of high seed shattering in target weed species. Advances in genetics and molecular biology have shown promise for reducing seed shattering in important crops, which could be exploited for manipulating seed shattering in weed species. Future research should focus on developing a better understanding of various seed shattering mechanisms in plants in relation to changing climatic and management regimes.

Strip Tillage and Crop Residue Retention Decrease the Size but Increase the Diversity of the Weed Seed Bank under Intensive Rice-Based Crop Rotations in Bangladesh

Cropping under conservation agriculture (CA) has become increasingly attractive among farmers in recent years. However, weed control may be more difficult during the transition to CA from conventional establishment methods due to the reduction in tillage intensity. Conversely, CA changes to weed dynamics can alter the weed seed bank in the longer run. In Bangladesh’s intensively cropped rice-based rotations, the nature of weed seed bank shifts over time after adopting CA are poorly known. Two 2-year studies were sampled from on-farm CA experiments under wheat-mungbean-winter rice and monsoon rice-mustard-winter rice rotations. We investigated the effects of reduced soil disruption in the form of strip-tillage (ST) combined with increased deposition of standing reside from previous crops (0 vs. 50%). The weed seed bank in 0–5, 5–10, and 10–15 cm depths of soil were quantified in a shade-house experiment by measuring weed emergence over 12 months in seedling trays. After 2 years of field study, the year-round count of emerged weeds from the seed bank showed that ST plus 50% mulch had a lower weed abundance and biomass and fewer weed species than that of conventional tillage (CT) without residue. The perennial weeds Ageratum conyzoides L., Alternanthera philoxeroides L., Cynodon dactylon L., Cyperus rotundus L., Jussia decurrence Walt., Leersia hexandra L., Scirpus mucronatus (L.) Palla., and Solanum torvum Sw. were enriched in the smaller-sized ST seed banks in terms of both density and biomass. The CT, on the other hand, was dominated by annual weeds: Cyperus difformis L., Cyanotis axillaris Roem., Echinochloa crus-galli (L.) Beauv., Eleusine indica L., Fimbristylis miliacea (L.) Vahl., and Rotala ramosior L. Overall, ST plus 50% residue had a more diverse seed bank than CT without mulch. The majority of weed seeds were amassed in the 0–5 cm soil depth of the ST, while most of them were accumulated in the 10–15 cm layer of the CT. The wheat-mungbean-winter rice rotation had a more diverse floristic composition with many more weed species than the monsoon rice-mustard-winter rice rotation.

Провокування проростання насіння падалиці пружинно-пальцевими боронами – важливий агротехнічний метод управління забур'яненістю агрофітоценозу

The purpose of the research is to investigate the quality of spring-finger harrow surface tillage to provoke the germination of carrion depending on the angle of the fingers. Research methods: theoretical – analysis of information resources and research results of spring harrows; laboratory-field – economic tests of the machine with planning of experiment, fixing of agrotechnical indicators; instrumental measurements; mathematical and statistical – processing of the obtained indicators and expert evaluation. Results. Experimental field studies of the quality of surface tillage with a spring-finger harrow were carried out in order to provoke the emergence of winter rapeseed. It was found that the harrow loosens and mulches the top layer of soil well, creating optimal conditions for the germination of weeds and weed seeds. The importance of the agrotechnical measure of field litter management and prospects for the use of spring-finger harrows in the system of soil-protective agriculture is analytically substantiated. Conclusions. The physical parameters obtained as a result of researches of a spring-finger harrow testify that at speed about 20 km / h with increase of an angle of inclination of spring fingers depth of their course increases in 1,6 times from 7,2 cm to 11,3 cm that corresponds to agricultural requirements to spring harrows (4-12 cm). The quality of soil crushing in terms of agronomically valuable aggregates up to 0-25 mm in size increases with satisfactory to excellent values with increasing angle of inclination of the fingers. The results of experimental studies show that the heavy spring-finger harrow Degelman Strawmaster SM 7000-50, in the presence of freshly cut rapeseed stubble of large size and clumps of chaff, provides satisfactory tillage, promoting the germination of rapeseed seeds and improving phytosanitary conditions for future field operations.

Decrease sensitivity of Eleusine indica treated with Paraquat and Glyphosate sub-lethal doses

Populations of Eleusine indica glyphosate-sensitive weed seeds taken from Polytechnic Negeri Medan Campus. This study aims to examine whether the use of sub-lethal doses of paraquat and glyphosate in three generations can cause a decrease in the sensitivity of the Eleusine indica population to each herbicide. This research was carried out at the Universitas Sumatera Utara Campus with a height of ± 25 m above sea level. This study used a paraquat herbicide under the recommended dosage of 200 g.a.i. ha−1 and glyphosate herbicide under the recommended dose 360 g.a.i. ha−1 with three replications. Data analysis using IBM SPSS Statistics 20 software.

Stimulation of natural enzymes for germination of mimosa weed seeds to enhanced bioethanol production.

Depleting fossil fuels target plant weeds which have the potential to be converted into efficient biofuels. In this study, mimosa seeds were utilized as a substrate for bioethanol production. This investigation was divided into three parts: breaking dormancy of seeds, mimosa seeds germination, and bioethanol production from mimosa seeds. Seed dormancy breaking was initiated by seeds soaked in hot distilled water to analyze the sugar quantity. Sugar content was measured relevance with root length results. According to results, root length obtained revealed that at 0.5-1.0 cm for root size has the most sugar availability. It was revealed that the total sugar 548.21 g/L and reducing sugar has a concentration of 248.67 g/L. Therefore, the broken dormancy of seeds using hot water at 95°C for 10min with a root length of 0.5-1cm was used for ethanol fermentation. Ethanol fermentation was done by free yeast cell and immobilized yeast by injecting yeast directly. The ethanol yield was measured on the 3rd day of every fermentation. Results showed that the free cell yeast during the 1st day of fermentation afforded an ethanol production of 57.574g/L, while the yield for immobilized yeast was 60.714g/L. Consequently, the ethanol yield on the 2nd day of fermentation from the directly injected immobilized yeast was 60.088g/L. Results revealed that the immobilization of yeast cells in fermentation provided a higher probability for bioethanol yield and could be utilized as a baseline for future bioethanol production. Stimulation of natural enzymes by germination of seeds for enhanced bioethanol production will be a novel approach towards next-generation biofuels.

Germination stimulatory activity of bacterial butenolide hormones from Streptomyces albus J1074 on seeds of the root parasitic weed Orobanche minor.

Damage caused by Orobanchaceae root parasitic weeds is a substantial agricultural problem for global food security. Many studies have been conducted to establish practical methods of control, but efforts are still required for successful management. Seed germination of root parasitic weeds requires host-derived germination stimulants including strigolactones (SLs). Studies on SLs have revealed that a butenolide ring is the essential moiety for SL activity as a germination stimulant. Interestingly, recent studies have revealed that butenolide hormones regulate the biosynthesis of secondary metabolites and mediate communication in actinomycete bacteria. Because of the structural similarity between SLs and the bacterial butenolides, we evaluated the germination stimulatory activity of butenolides isolated from Streptomyces albus J1074 on root parasitic weeds. These butenolides were found to specifically induce seed germination of Orobanche minor. Our findings contribute to understanding the molecular mechanisms of germination stimulant perception and to the development of a method for their biological control.

Macrophomina phaseolina (Tassi) Goid Culture Filtrates is a Lucrative Source for Weed Control

The mycoherbicides have been recognized as an effective approach for weed control as being eco-friendly, low cost, and of long-lasting. This research was carried out to evaluate the herbicidal effect of Macrophomina phaseolina, the causal of sesame charcoal rot. The fungal culture was extracted with water and the extract toxicity was evaluated by seed germination, detached leaf, and whole plant bioassays on several weed species of Iraq (Cynanchum actum, Malva parviflora, Sorghum halepense, Lolium rgidum, and Silybum marianum). The results revealed that the extract of the fungal culture was significantly inhibited the germination of the examined weeds seeds by more than 86.7 %. The detached leaf bioassay also indicated that the culture extract was of potent toxic effect to all examined weed species, regardless their types (broad or narrow and mono or dicotyledonous). The phytotoxicity symptoms appeared on the detached leaves were as tissue and chlorophyll disintegration, yellowing, necrosis, and death. The same toxic symptoms were also recorded on the whole plant bioassay in vivo but the weed species of the narrow leaves however, showed significantly much less effect. The phytotoxicity on the examined weed species ranged from 66 to 83%. Moreover, the fungal culture extract was also found to be of potent toxic effect to milk thistle (Silybum marianum) despite the application method as foliar spraying or root immersing with 100% and 20% of the extract respectively. The results of this research showed for the first time the effect of M. phaseolina culture filtrates as a potent herbicide potential on different weed species.

Thirty‐six years of no‐tillage regime altered weed population dynamics in soybean

AbstractChanges to tillage practices can impact weed species composition and population dynamics in arable fields. The objective of this study was to evaluate and compare the impact of long‐term (36 yr) no‐tillage (NT) and conventional‐tillage (CT) systems on weed species composition, density, seedling emergence, and diversity, in a continuous soybean [Glycine max (L.) Merr.] system in Southeast Texas. Results from 2016 and 2017 observations showed that weed species composition varied between CT and NT, and the total density was greater in NT (14 and 86 plants m–2 for summer and winter annuals, respectively) compared to CT (3 and 45 plants m–2, respectively). Moreover, tall waterhemp [Amaranthus tuberculatus (Moq.) Sauer], prostrate spurge [Chamaesyce humistrata (Engelm. ex Gray) Small], and red sprangletop [Dinebra panicea (Retz.) P.M. Peterson & N. Snow] emergence was delayed in NT compared to CT. Vertical distribution (70‐cm depth) of viable weed seeds in the soil profile was also influenced by tillage regime; greater proportion of weed seeds were present on the soil surface (0–5 cm) in NT (57–80% among different species) compared to CT (38–56%). However, weed diversity indices did not differ between CT and NT. Results indicate that long‐term NT, even with herbicide management, can lead to greater weed densities with a shift towards small‐seeded annual species (common purslane [Portulaca oleraceae L.], parsley‐piert [Aphanes arvensis L.], cutleaf groundcherry [Physalis angulate L.]). Growers transitioning to NT should be cognizant of potential changes to weed population dynamics as a result of altered tillage regime and devise strategies for effective management.

Proportion of Grassland at Landscape Scale Drives Natural Pest Control Services in Agricultural Landscapes

Managing regulating ecosystem services delivered by biodiversity in farmland is a way to maintain crop yields while reducing the use of agrochemicals. Because semi-natural habitats provide shelter and food for pest enemies, a higher proportion of semi-natural habitats in the landscape or their proximity to crops may enhance pest control in arable fields. However, the ways in which the spatial arrangement of these habitats affects the delivery of this beneficial ecosystem service to crops remains poorly known. Here, we investigated the relative effects of the amount of grassland in the landscape versus the distance to the nearest grassland on the predation rates of weed seeds and aphids into 52 cereal fields. We found that both seed and aphid predation levels increased with the proportion of grassland in a 500 m radius buffer while the distance to the nearest grassland displayed no effect. We show that increasing from 0 to 50% the proportion of grasslands in a 500 m radius, respectively, increased seed and aphid predation by 38 and 20%. In addition to the strong effect of the proportion of grassland, we found that seed predation increased with the proportion of forest fragments while aphid predation increased with the proportion of organic farming in the landscape. Overall, our results reveal that natural pest control in cereal crops is not related to the distance to the nearest grassland, suggesting that natural enemies are not limited by their dispersal ability. Our study indicates that maintaining key semi-natural habitats, such as grasslands, is needed to ensure natural pest control and support food production in agricultural landscapes.