Weed Seeds Research Articles

No-tillage altered weed species dynamics in a long-term (36-year) grain sorghum experiment in southeast Texas

AbstractTillage regimes can influence weed population dynamics and, consequently, the choice of appropriate weed management practices. Studies were conducted in 2016 and 2017 in a long-term (36-yr) grain sorghum [Sorghum bicolor (L.) Moench ssp. bicolor] experiment at Texas A&M University, College Station, to determine the impact of long-term no-till (NT) and conventional till (CT) systems on weed species dynamics. Higher densities of johnsongrass [Sorghum halepense (L.) Pers.], prostrate spurge [Chamaesyce humistrata (Engelm. ex A. Gray) Small], waterhemp [Amaranthus tuberculatus (Moq.) Sauer], and henbit (Lamium amplexicaule L.) were recorded in the NT system compared with the CT system. Further, the NT system showed greater weed diversity (Shannon-Wiener index, H = 0.8) and species richness (S = 6.2), compared with the CT system (H = 0.6, S = 4.2). Seedling emergence of some dominant weed species was also delayed in the NT system. In the CT system, 50% emergence of S. halepense (8.5 C base temperature) and waterhemp (10 C base temperature) occurred at 59 and 63 growing degree days (GDD), respectively, whereas 68 and 75 GDD, respectively, were required in the NT system. Further, a greater proportion (61%) of the viable seedbank was present at the top 5 cm of the soil in the NT system compared with the CT system (46%). Overall, findings from this 36-yr-long tillage experiment have revealed that the NT system had greater weed densities (especially of the perennial weed S. halepense) and a high proportion of weed seeds (particularly small-seeded annuals) on the topsoil layer, corroborating some earlier reports that were based on short-term investigations. Findings indicate that growers transitioning to NT systems should be mindful of potential shifts in weed species dominance and develop appropriate management tactics.

Integration of Steam with Allyl-isothiocyanate for Soil Disinfestation

Steam has long been used to disinfest greenhouse soils. However, there is increasing interest in expanding the use of steam for in-field soil disinfestation as an alternative to chemical fumigants. Previous studies demonstrated that allyl-isothiocyanate (AITC) reduced viability of weed seeds and plant pathogen propagules, but AITC has a low vapor pressure and is relatively immobile in soil. Heat has been used in the past to enhance the mobility of soil fumigants such as methyl bromide (i.e., “hot gassing”). The effect of steam heat on the mobility of AITC is unknown. The objective of this study was to investigate the potential synergistic effect of steam plus ATIC against weed seeds and a plant pathogen. AITC alone did not reduce the viability of the four weed species and the number of Verticillium dahliae microsclerotia. The steam + AITC treatment reduced the viability of V. dahliae at 12.5 and 18 cm distances by 82% and 88%, respectively, and knotweed and nettle seeds at 70 cm from injection point by 75% and 86%, respectively, from the center of microplots compared with steam alone. The results suggest that AITC and steam have a complementary effect on soilborne pests because steam increases the mobility of AITC.

The effects of soil tillage techniques on weed flora in high input barley systems in northern Spain

In barley cropping systems of northern Spain, agronomic practices and weather conditions are key components of weed control efficacy. We compared the short-term effects of conventional tillage with minimum tillage (MT) and zero tillage (ZT), in barley monoculture and barley rotation systems. Weed density and weed species number were measured at tillering and flowering barley stages. We found that tillage system can influence weed density and weed species establishment due to, in part, the available light for weed seeds. The results obtained indicate that the MT system facilitates the prevalence of the grass weed Bromus diandrus Roth (50.37%) and the annual dicots Galium aparine (L.) and Buglossoides arvensis (L.) I.M. Johnst. abundant were high in the MT system too, 43.71% and 43.97% respectively. The germination of these species showed a high dependence on light availability. We saw that barley-monoculture plots had a large infestation of Bromus (71.29%) and barley-rotated plots presented more infestation of Galium and Buglossoides (74.36% and 84.4%, respectively). After herbicide application, weed infestation in conservation systems was reduced in barley-rotated plots compared with barley-monoculture. If conservation systems avoided the presence of dominant weeds, the weight of each weed species was balanced within competitive relationships of the cropping systems. Our results confirmed that MT and ZT systems favour different weed species emergences in barley-rotated plots. The combination of MT and barley-rotated cropping system resulted in greater weed diversity and lower total weed density.

Black Plastic Tarps Advance Organic Reduced Tillage I: Impact on Soils, Weed Seed Survival, and Crop Residue

Intensive tillage degrades soil structure, decreases soil organic matter, and can cause soil compaction and erosion over time. Organic vegetable farmers are often dependent on tillage to incorporate crop residue, control weeds, and prepare seedbeds. Black, impermeable, polyethylene tarps applied on the soil surface and removed at planting can help suppress weeds before planting and reduce farmers’ reliance on tillage. However, little is known about how black tarps affect planting conditions and how they can be used to advance reduced tillage production systems. This study investigated the effects of tarp use and tarp duration on the soil environment, surface cover crop residue, and weed suppression to assess the efficacy of using tarps to improve reduced- and no-till practices for organic vegetable production. Experiments were conducted at three sites in the northeastern United States (Freeville, NY; Riverhead, NY; and Monmouth, ME) for 2 years. Following the termination of an oat cover crop, tarps were applied over untilled soils and left in place for four time periods: untarped (control), 3 to 5 weeks (short), 6 to 8 weeks (mid), and 10 or more weeks (long) before two removal dates. Soil moisture and temperature, cover crop residue, soil inorganic nitrogen, weed seed survival, and weed percent cover were measured after tarp removal. Soil moisture and temperature were generally higher under tarps at the time of removal compared with untarped areas at 10% to 55% and 1 to 3 °C, respectively, but the effects were inconsistent. Tarps significantly increased soil nitrate concentrations by 2-times to 21-times with longer tarp durations, resulting in higher concentrations compared with untarped controls. Tarps did not affect the amount of soil covered by cover crop residue and had no consistent effects on weed seed survival of Amaranthus powellii S. Wats. or Chenopodium album L., two common annual weed species in the Northeast. Tarping for at least 3 weeks reduced the weed percent cover by 95% to 100% at the time of removal. Increasing tarp duration beyond 3 weeks did not affect any measures except soil nitrate concentrations. These results indicate that tarps can facilitate the use of reduced-till and no-till practices for organic vegetables by creating a nutrient-rich and moist soil environment free of emerged weeds before planting without soil disturbance.

Germinable weed seed-bank response to plant residue application and hand weeding under two contrasting tillage systems in a granite-derived clay loam soil in Zimbabwe

High levels of weed infestation are among the major reasons for the limited adoption of conservation agriculture techniques by farmers in sub-Saharan Africa. This study investigated the effects of plant residue application (zero: NR, low: LR, medium: MR and high: HR) and hand weeding (twice: TWI, thrice: THR, four times: FOU and clean weeding: CLE) under two tillage systems (basin planting: BASIN, and conventional tillage: CT) on weed seed density in a clay loam soil at Chinhoyi University of Technology experimental farm, Zimbabwe. During 2014/15, the number of germinable Amaranthus hybridus L. seeds was higher in BASIN+NR+THR and BASIN+MR+TWI than other treatments. Germinable propagules of Cyperus L. spp. were fewer in NR+FOU and NR+CLE than NR+TWI and NR+THR plots. In 2015/16, TWI resulted in an increase of 52.3−79.5% of the number of germinable A. hybridus seeds compared to THR, FOU and CLE. Germinable weed seeds increased by 67.1% for Alternanthera pungens Kunth and 164.8% for Galinsoga parviflora Cav. in the surface compared to the subsurface layers of BASIN but were evenly distributed in CT. The results suggest that cultural practices exert selection pressure on individual weed species which may change the weed species composition in the soil seed bank.

Weed Flora and Soil Seed Bank Composition as Affected by Tillage System in Three-Year Crop Rotation

In recent years, there has been an increasing interest around agricultural science and practice in conservation tillage systems that are compatible with sustainable agriculture. The aim of this study was to assess the qualitative and quantitative changes in weed flora and soil seed bank under reduced tillage and no-till (direct sowing) in comparison with traditional ploughing. In the crop rotation: pea/rape—winter wheat—winter wheat the number and dry weight of weeds increased with the simplification of tillage. The seed bank was the largest under direct sowing and about three times smaller in traditional ploughing. Under direct sowing, most weed seeds were accumulated in the top soil layer 0–5 cm, while in the ploughing system most weed seeds occurred in deeper layers: 5–10 and 10–20 cm. In the reduced and no-till systems, a greater percentage of perennial and invasive species, such as Conyza canadensis L., was observed. The results show that it is possible to maintain weed infestation in the no-till system at a level that does not significantly affect winter wheat yield and does not pose a threat of perennial and invasive weeds when effective herbicide protection is applied.

Evaluation of ultrasound technology to break seed dormancy of common lambsquarters (Chenopodium album).

Although seed dormancy is advantageous for annual plants in the wild, unsynchronized germination in the laboratory leads to increased error in measurements. Therefore, techniques to promote and synchronize germination are routinely used. Ultrasound is one of the newest methods for breaking dormancy in weed seeds. We have investigated whether ultrasonic waves can be used to break seed dormancy of common lambsquarters (Chenopodium album), a highly competitive annual weed that leads to significant reduction of yields of corn, soybeans, and sugar beets. Ultrasonic waves with frequency of 35 kH were applied for 0 (control), 5, 10, 15, and 30 min using a completely randomized design. The results showed that the use of ultrasound waves generally enhanced the traits under investigation in the treated samples compared with the control sample. The maximum enhancement of germination percentage (180%), seedling dry weight (78%), and seedling vigor index I (271%) and II (392%) was seen in the common lambsquarters samples treated with ultrasound for 15 min and seedling length (40%) at 30 min compared with the control samples. Radical lengths were not statistically different from controls under any treatment and plumule length only increased marginally. These changes are reflected in seedling vigor index I and II measurements. For some of these traits, increasing the length of ultrasound treatment to 30 min had negative effects. These results demonstrate that ultrasound technology can be used as a quick, and efficient nondestructive method to break seed dormancy in common lambsquarters.

Innovative ways to process poultry waste

This paper provides an overview of methods for processing and recycling chicken droppings. Poultry farms are a source of litter formation in an amount much larger than the main products. The litter contains up to 80% organic matter, many trace elements, all essential amino acids, growth regulators, vitamins, nitrogen and phosphorus. According to the Federal waste catalog, fresh chicken droppings belong to the 3rd hazard class. Fresh dung contains a significant amount of weed seeds, helminth eggs and pathogenic microorganisms. Dung is a source of toxic gases-ammonia, hydrogen sulfide, methane, carbon monoxide. Without recycling, manure becomes a source of environmental pollution. Disposal of chicken droppings is a difficult issue for many farms. Modern trends in the processing and use of poultry manure: 1) direct application to the soil without additional treatment, 2) Processing by passive and active composting, 3) Vermicomposting, 4) Processing with the help of housefly larvae, 5) Dehydration and drying (mechanical, thermal, vacuum), 6) Pyrolysis at t = 450-550 °C, 7) Plasma gasification, 8) thermal depolymerization Technology, 9) Direct combustion in steam and hot water boilers, 10) Microbiological conversion, 11) anaerobic digestion in Methane tanks with the formation of biogas, 12) Dung as a component of compound feed for cattle. The considered technologies of utilization of bird droppings do not fully contribute to the preservation of the environment and production. At the present stage, the industry needs an environmentally friendly and cost-effective biotechnology for processing manure, which makes it possible to turn organic waste into valuable raw materials for obtaining feed, fuels, fertilizers, and substrates for the chemical and microbiological industries. The future of waste management is in nature-like technologies, because in nature, all the necessary processing mechanisms are already in place.

A Review of Non-Chemical Weed Control Practices in Christmas Tree Production

Weeds interfere with Christmas tree growth at any time and at any stage of production. Growers mostly rely on mechanical mowing and applications of herbicides for weed control in their fields. However, herbicides can be phytotoxic to non-target plants, can cause environment-related issues, and their repeated application can even cause herbicide-resistant weeds. The main objective of this manuscript is to provide a review of non-chemical weed control strategies in Christmas tree production and identify areas where current practices could potentially be improved or in which further research is required. Preventing the introduction of weed seeds requires controlling weeds along farm roads, maintaining clean equipment, and eliminating new weeds before they start seeding. Mowing helps to reduce the number of seeds produced by the weeds and can significantly reduce competition with trees. Shropshire sheep are well suited for grazing Christmas tree plantations as they prefer grazing on grasses and weeds rather than on coniferous trees. Weeds can also be controlled around Christmas trees by mulching. Organic mulch can improve soil moisture, maintain soil temperatures, enhance root establishment and transplant survival, and improve plant establishment and overall growth. Incorporating cover crops into Christmas tree plantations may improve tree growth, quality, and soil fertility and can supplement conventional nitrogen fertilizers. However, if cover crops are not properly managed, they can be highly competitive with the trees. Flaming can cause suppression of many annual weed species but is less effective on larger weeds and needs to be applied with caution. Several insects have been used as biological agents to control selective weed species. However, further research is required to focus on several potential biological agents, different types and depths of mulches, on cover crops types and their competition with different species of Christmas trees and their effects on seedling survival and growth.

Combined Effects of Dewatering, Composting and Pelleting to Valorize and Delocalize Livestock Manure, Improving Agricultural Sustainability

An agronomic strategy to mitigate climate change impact can be the build-up of soil organic carbon. Among agronomic management approaches, the administration of organic fertilizers like livestock manure represents an effective strategy to increase soil organic carbon. However, livestock manure usually contains a high amount of water, reducing its sustainable delocalization and impacting on greenhouse gas emissions and nutrient leaching. Furthermore, the possible presence of weed seeds and harmful microorganisms could reduce the agronomic value of the manure. To overcome these issues, the combined effects of dewatering, composting and pelleting were investigated on livestock manure to produce sustainable organic fertilizers. Our results showed that composting and pelleting can represent a feasible and sustainable solution to reduce the potential risks related to the presence of weed seeds and harmful bacteria, concentrating nutrients and allowing a sustainable valorization and delocalization of the livestock manure. In addition, the processed manures were assessed as fertilizers in the growing medium (GM), displaying an increase in water retention and nutrient availability and a decrease of GM temperature and weed seed emergences. However, further study is needed to validate, both in open field and greenhouse productions, the effects of the proposed fertilizers in real cropping systems.

Connected Carabids: Network Interactions and Their Impact on Biocontrol by Carabid Beetles.

Carabid beetles can greatly contribute to biocontrol in agroecosystems, reducing both insect pests and weed seeds. However, insect foraging and feeding behavior can be highly dependent on the interaction network and spatial structure of the environment, which can make their biocontrol contributions variable. In the present article, we explore how the interaction network of carabids can affect their behavior and how spatial vegetation structure and specific agronomy practices can, in turn, affect the strength of interactions in their network. We suggest that research on carabid biocontrol should move toward an approach in which the network of interactions among pests, carabids, and other organisms within its spatial structure is evaluated, with equal focus on direct and indirect interactions, and provide examples of tools to do so. Overall, we believe this approach will improve our knowledge of carabid networks, help to elucidate the underlying mechanisms of biocontrol, and lay the foundation for future biocontrol strategies.

Germination ecology of hairy fleabane (Conyza bonariensis) and its implications for weed management

AbstractHairy fleabane [Conyza bonariensis (L.) Cronquist] is a problematic weed in Australian no-till cropping systems. Consequently, a study was conducted to examine the effect of temperature, light, salt stress, osmotic stress, burial depth, and sorghum crop residue on germination and emergence in two populations (C and W: collected from chick pea [Cicer arietinum L.] and wheat [Triticum aestivum L.] fields, respectively) of C. bonariensis. Both populations were able to germinate over a wide range of alternating day/night temperatures (15/5 to 35/25 C); however, the C population had optimum (and similar) germination over the range of 20/10 and 30/20 C, while the W population showed maximum germination at 25/15 C. A negative relationship was observed between osmotic potential and germination, with 31% and 14% germination of the C and W populations at −0.6 MPa, respectively. These observations suggest that population C was more tolerant to higher osmotic potentials than population W. Seeds of both populations germinated when exposed to a wide range of sodium chloride levels (NaCl, 0 to 200 mM); however, beyond 200 mM NaCl, no germination was observed in either population. Maximum germination of the C (70%) and W (41%) populations was observed on the soil surface with no emergence from a burial depth of 1 cm. The application of sorghum residue at an amount of 6,000 kg ha−1 reduced emergence of the C and W populations by 55% and 58%, respectively, compared with the no-residue treatment. Knowledge gained from this study suggests that the following strategies could be used for more efficacious management of C. bonariensis: (1) a shallow-tillage operation to bury weed seeds in conventional tillage systems, and (2) retention of sorghum residue on the soil surface in no-till systems.

Evaluation of the Phytotoxicity of Urochloa humidicola Roots by Bioassays and Microscopic Analysis. Characterization of New Compounds.

Herbicides are a key element in agriculture but they do cause environmental problems and natural alternatives are being sought. In this context, invasive plants could provide an as yet unexplored source for the development of future herbicides. Urochloa humidicola has great invasive potential in Brazilian environments as it hampers the establishment of other plants. The phytotoxicity of U. humidicola root extracts has been evaluated, and the major components have been identified. The phytotoxicity of the extract was assessed in the wheat coleoptile assay on seeds of troublesome weeds and on Anadenanthera colubrina, a tree species used in ecological restoration programs. The ethyl acetate extract showed the highest activity, and the most affected weeds were E. crus-galli, M. maximus, and A. viridis with the latter weed more affected by the extract than by the herbicide Logran. Microscopic ultrastructural analysis of A. colubrina roots indicated possible signals of cell death. Seven compounds were identified in the ethyl acetate extract of which one diterpene and four saponins are new. Six of these compounds were tested in the wheat coleoptile bioassay. The most active were diterpene 1 and saponins 2, 3, and 6. The phytotoxic activity of U. humidicola explains the issues observed in ecological restoration with A. colubrina in the presence of Urochloa species, and its effect on weeds reinforces its potential use in agriculture.

Effect of pre-composting on seed viability and subsequent vermicomposting of an invasive alien weed,Alternanthera ficoidea (L.) P. Beauv.

In the present study, the suitability of an invasive weed, Alternanthera ficoidea (L.) P. Beauv. (AF) biomass for vermicomposting has been tried by subjecting three different combinations of the weed and cow dung (CD) through 28 days pre-composting followed by 50 days vermicomposting with Eudrilus eugeniae. The maximum temperature recorded in P1 (1CD:1AF), P2 (2CD:1AF) and P3 (1CD:2AF) during pre-composting was 66, 62 and 67°C respectively. The seed viability study using pre-composted substrates, for weed seeds if any, revealed that there were no seedlings appeared in P1 and P3 up to 60 days, while 41.57% germination was observed for P2 compared to initial non pre-composted substrate. The C/N ratio in all vermibed combinations was found to decline significantly (P<0.05) at the end of vermicomposting from the initial levels as well as from the substrate combinations without earthworms (control). The lowest C/N ratio of 14.56 was found in V2 (2CD:1AF) followed by V1 (1CD:1AF) and V3 (1CD:2AF). The growth and reproduction of Eudrilus eugeniae was well supported by the combination of V1 and V2 which were significantly higher than V3 (P<0.05). The tests on germination of Alternanthera ficoidea seeds in vermicompost confirmed that there were no viable seeds in V1 and V3 vermicomposts while V2 vermicompost showed 16.77% viability in comparison with the control (non pre-composted). Based on germination of weed seeds in vermicompost, reduction of C/N ratio, growth and reproduction of Eudrilus eugeniae during vermicomposting, it is concluded that 28 days pre-composting followed by 50 days vermicomposting of 1:1 (CD+AF) ratio of substrate combination is suitable for utilizing the biomass of Alternanthera ficoidea for nutrient recovery and vermicompost production without any harm to the environment.

Key Factors Affecting Weed Seeds' Germination, Weed Emergence, and Their Possible Role for the Efficacy of False Seedbed Technique as Weed Management Practice

Important parameters that influence weed seeds’ germination and seedlings’ emergence can affect the efficacy of false seedbed as weed management practice. These parameters consist of environmental factors such as soil temperature, soil water potential, exposure to light, fluctuating temperatures, nitrates concentration, soil pH and the gaseous environment of the soil. Soil temperature and soil water potential can exert a great influence on composition of the weed flora of a cultivated area. Base soil temperatures and base water potential for germination vary among different weed species and their values can be possibly used to predict which weeds will emerge in a field and also the timing of emergence. Predicting the main flush of weeds in the field could maximize the efficacy of false seedbed technique as weed management practice. Timing, depth and type of tillage are important factors affecting weed emergence and subsequently the efficacy of false seedbed. The importance of shallow tillage as weed control method in the false seedbed technique has been highlighted. Further research is needed to understand and explain all the factors that can affect weed emergence so as to maximize the effectiveness of eco-friendly weed management practices such as false seedbed in different soils and under various climatic conditions.

Seed destruction of weeds in southern US crops using heat and narrow-windrow burning

AbstractNarrow-windrow burning has been a successful form of harvest weed seed control in Australian cropping systems, but little is known about the efficacy of narrow-windrow burning on weed seeds infesting U.S. cropping systems. An experiment was conducted using a high-fire kiln that exposed various grass and broadleaf weed seeds to temperatures of 200, 300, 400, 500, and 600 C for 20, 40, 60, and 80 s to determine the temperature and time needed to kill weed seeds. Weeds evaluated included Italian ryegrass, barnyardgrass, johnsongrass, sicklepod, Palmer amaranth, prickly sida, velvetleaf, pitted morningglory, and hemp sesbania. Two field experiments were also conducted over consecutive growing seasons, with the first experiment aimed at determining the amount of heat produced during burning of narrow windrows of soybean harvest residues (chaff and straw) and the effect of this heat on weed seed mortality. The second field experiment aimed to determine the effect of wind speed on the duration and intensity of burning narrow windrows of soybean harvest residues. Following exposure to the highest temperature and longest duration in the kiln, only sicklepod showed any survival (&lt;1% average); however, in most cases, the seeds were completely destroyed (ash). A heat index of only 22,600 was needed to kill all seeds of Palmer amaranth, barnyardgrass, and Italian ryegrass. In the field, all seeds of the evaluated weed species were completely destroyed by narrow-windrow burning of 1.08 to 1.95 kg m−2 of soybean residues. The burn duration of the soybean harvest residues declined as wind speed increased. Findings from the kiln and field experiments show that complete kill is likely for weed seeds concentrated into narrow windrows of burned soybean residues. Given the low cost of implementation of narrow-windrow burning and the seed kill efficacy on various weed species, this strategy may be an attractive option for destroying weed seed.

Allelopathic properties of Calliandra haematocephala Hassk. extracts and fractions as an alternative for weed management in quinoa and rice crops

In this study, aqueous extracts of Calliandra haematocephala Hassk. leaves and inflorescences were tested on seeds of quinoa (Chenopodium album L.) and rice (Oryza sativa L.), and on some of the most noxious-associated weeds, Chenopodium album L. and Holcus lanatus L. in quinoa, and Echinochloa crus-galli (L.) P. Beauv., Echinochloa colona L., Eclipta prostrata L. and Rottboellia cochinchinensis (Lou.) W.D. Clayton in rice. The objectives were to identify extract concentrations at which 50 and 90% of germination (GR_{[50,90]}) and radicle elongation (RR_{[50,90]}) were inhibited, to fractionate inflorescence extracts for facilitating identifying the chemical group causing allelopathic effects, and to evaluate the fraction showing the stronger weed suppression effects and the least crop damage. Increasing extract concentration rates (0, 6.25, 12.5, 25, 50 and 100% crude extract) were applied to seeds of target crops and weeds. Flower extracts at rates < 0.30 produced GR_{[50]} and RR_{[50]} on H. lanatus, and GR_{[90]} and RR_{[90]} in C. album, while quinoa seeds were not affected. Rice and its target weeds were minimally affected by flower extracts, whereas radicle elongation of all species was significantly reduced. A concentration rate > 0.52 caused the RR_{[50]} on rice and all its target weeds. Fractions were quantitatively and qualitatively analysed to detect phytochemical groups, using specific chemical reagents and thin-layer chromatography (TLC). The fraction F3 from aqueous flower extract showed a high content of flavonoids, assumed as the potential allelochemical substance. Total flavonoid content in F3 was quantified as 2.7 mg of quercetin per g F3, i.e., 12.8 mg of quercetin per g of inflorescence material. Additionally, field equivalent extract rates obtained from the harvested fresh inflorescence biomass could be determined. These rates ranged between 90 and 143 mL l−1 of F3 aqueous fraction, while for ethanol F3 were 131 mL l−1. Our results are encouraging for finding sustainable and ecologically friendly alternatives for weed management in crops of high nutritional value, contributing also to counteract the growing problem of herbicide resistance.

The contribution of semi‐natural habitats to biological control is dependent on sentinel prey type

Abstract It is widely recognized that landscape factors affect the biological control of weed seeds and insect pests in arable crops, but landscape effects have been found to be inconsistent between studies. Here, we compare six different types of sentinels (surrogate prey that was either live insects or seeds) to measure the effects of semi‐natural habitats at field to landscape scales on levels of biological control in winter wheat in the UK. Sentinels were located in fields adjacent to three boundary types: grassy margin, hedgerows or woodland to study the local scale effects and in landscapes of varying heterogeneity in study areas of 1‐km radius. Overall, mean levels of predation were higher for most insect prey (60.8%) located on the ground compared to the crop (12.2%) and was lower for seeds (5.8%). Predation of sentinels on the ground was attributed to generalist predators. Semi‐natural habitats had both positive and negative effects at field and landscape scales, but the response varied with the sentinel type. Herbaceous linear semi‐natural habitats had positive effects at local scales for Calliphora vomitoria and Sitobion avenae sentinels and provide evidence that farmers can introduce linear herbaceous features to benefit biological control. In contrast, our distance‐weighted kernel models identified a positive relationship between woody habitats and the predation of C. vomitoria and Chenopodium album. Natural aphid infestations were lower in landscapes with more semi‐natural habitat. Synthesis and applications. Sentinels may be sensitive enough to detect variation in levels of biological control influenced by semi‐natural habitats, but this study confirms that landscape effects differ for different types of sentinel prey. This implies that it may not be possible to categorize landscapes as pest suppressive using a single sentinel type. Future studies should therefore consider using multiple sentinels to give a better perspective on predation intensity. The resulting recommendations for farm management include planting woodland adjacent wheat fields infested with seed predators and positioning herbaceous linear habitats adjacent wheat fields infested with Sitobion avenae, particularly if fields are bordered by woody liner habitats due to their association with decreased S. avenae predation.

Alternative method of composting on a reclaimed municipal waste landfill in accordance with the circular economy: Benefits and risks

Waste composting is becoming a key element of integrated waste management. Composting has a number of advantages, including economic benefits, improvement of soil properties through the use of compost, reduction in the use of chemical fertilisers, and minimization of environmental pollution. Composting on a landfill surface appears to be an economical solution that can help close the waste loop and material cycle. In this study, a composting plant located on a landfill surface was analysed. The main objective of the research was to identify the species of plants growing in the organic fraction of municipal solid waste in temporary storage, in the composting plant, and in maturing compost located in a reclaimed plot at the landfill site. During monitoring, 88 plant species were identified altogether. It was observed that compost can become a source of weed infestation. To control the presence of weeds in the compost, basic principles of composting are to be followed to reduce the quantity of weed seeds. The thermophilic phase must occur to reduce the viability of seeds in the input materials and sufficient moisture must be ensured during the composting process. When these principles are strictly observed and the stored compost is maintained without vegetation, the supply of seeds in the compost will be low, and the undesirable spread of plant species to adjacent areas will be controlled. The results showed that the use of the obtained compost did not result in the propagation of weed species. This study demonstrates that composting on a reclaimed landfill offers various advantages such as a closed waste management cycle, coverage of the active landfill body, and fertilisation of the reclaimed part of the landfill.

Specificity of potential contamination of rice checks with weed seeds

Goal. To analyze the potential level of contamination of arable soil layer weed seeds and to establish the specificity of the changes in such reserves during the vegetation period of crops. The study was performed on rice checks of the Institute of rice of NAAS in the Kherson region in the 2017—2019 biennium.&#x0D; Methods. Research field, small and laboratory. To determine the factor of seeds and vegetative reproductive organs of weeds in certain soil horizons of rice fields per unit area (pieces/m2) was selected soil samples by the method of A. N. Kiseleva — twice per season, in spring and after harvest of rice. The arable soil was divided into three layers (10 cm each). To determine the viability of seeds used method of staining their tetrazoles. The results were compiled and analyzed.&#x0D; Results. A comparison of the level of potential contamination between horizons showed the highest number of weed seeds in the horizon of 0—10 cm on average, 16041 pieces/ m2, which is 47.6% of the overall presence of weeds in the soil (33650,2 pieces/ m2). In the soil horizon 10—20 cm the number of weed seeds reached 10489.2 pieces/m2, or 31.2% of the debris of the upper horizon. In the lower horizon of 20—30 cm level of the presence of weed seeds was low — 7119.8 pieces/ m2, which amounts to 21.2% from that of the top horizon of the soil. Among the weed species whose seeds were present in soil samples of the top horizon of 0—10 cm, the largest part was Kuga Astrakhantseva Scirpus mucronatus L. — 59.8%, in another place Boule seeds Kuga razveseloj Scirpus supinus L. — 31.8%, Polygonum Persicaria hydropiper L. percetage — 1004.7 pieces/ m2 (6,3%), chicken millet Echinochloa crus galli L. — 329.1 pieces/m2 (2.1%). Other types were less in the stocks of weed seeds.&#x0D; Conclusions. During the vegetation period inventory quantities of seeds of change and by autumn are increasing. The largest amplitude value of the stock of weed seeds is manifested in the upper 0—10 cm horizon of the arable layer and reaches to 12.3%. Qualitative and timely implementation of measures to protect rice crops from sowing to the presence of weeds provides a gradual reduction in the volumes of their Bank of seeds in the soil.