Effect Of Herbicide Residues Research Articles

Enhanced capacity of a leaf beetle to combat dual stress from entomopathogens and herbicides mediated by associated microbiota.

Herbicides have demonstrated their impact on insect fitness by affecting their associated microbiota or altering the virulence of entomopathogenic fungi toward insects. However, limited research has explored the implications of herbicide stress on the intricate tripartite interaction among insects, associated bacterial communities, and entomopathogens. In this study, we initially demonstrated that associated bacteria confer a leaf beetle, Plagiodera versicolora, with the capability to resist the entomopathogenic fungus Aspergillus nomius infection, a capability sustained even under herbicide glyphosate stress. Further analysis of the associated microbiota revealed a significant alteration in abundance and composition due to glyphosate treatment. The dominant bacterium, post A. nomius infection or following a combination of glyphosate treatments, exhibited strong suppressive effects on fungal growth. Additionally, glyphosate markedly inhibited the pathogenic associated bacterium Pseudomonas though it inhibited P. versicolora's immunity, ultimately enhancing the beetle's tolerance to A. nomius. In summary, our findings suggest that the leaf beetle's associated microbiota bestow an augmented resilience against the dual stressors of both the entomopathogen and glyphosate. These results provide insight into the effects of herbicide residues on interactions among insects, associated bacteria, and entomopathogenic fungi, holding significant implications for pest control and ecosystem assessment.

Ecotoxicological effects of commercial herbicides on the reproductive system of aquatic arthropod Limnocoris submontandoni (Hemiptera: Naucoridae).

Worldwide, conventional agriculture makes extensive use of pesticides. Although the effects of herbicides are relatively well known in terms of environmental impacts on non-target organisms, there is very little scientific evidence regarding the impacts of herbicide residues on aquatic arthropods from tropical conservation areas. This study evaluates for the first time the toxicity of the herbicides ametryn, atrazine, and clomazone on the aquatic insect Limnocoris submontandoni (Hemiptera: Naucoridae). The lethal concentration (LC50) of herbicides was evaluated for these insects, as well as the effect of the herbicides on the insects' tissues and testicles. The estimated LC50 was 1012.41, 192.42, and 46.09 mg/L for clomazone, atrazine, and ametryn, respectively. Spermatocyte and spermatid changes were observed under the effect of atrazine, and effects on spermatogenesis were observed for some concentrations of clomazone, with apparent recovery after a short time. Our results provide useful information on the effects of herbicide residues in aquatic systems. This information can help minimize the risk of long-term reproductive effects in non-target species that have been previously overlooked in ecotoxicology studies.

Herbicide exposure alters the effect of the enthomopathogen Beauveria bassiana on immune gene expression in mealworm beetles

Concerns have grown worldwide about the potentially far-reaching effects of herbicides on functional biodiversity in agroecosystems. Repeated applications over time can lead to accumulation of residues in soil, water, and food and may have negative impacts on non-target organisms. However, the effects of herbicide residues on interspecific relationships, such as host-pathogen interactions, are poorly studied. In this study, we evaluated the effects of two different concentrations of a commercial pendimethalin-based formulation (PND), the residual contamination (S, 13 ppm) in treated soils and the maximum residue level allowed by the European Commission in cereals (EU, 0.05 ppm). We tested the effect of PND on the biological interaction between the mealworm beetle Tenebrio molitor Linnaeus, 1758 and the entomopathogenic fungus Beauveria bassiana Vuillemin, 1912 (Bb, strain KVL 03–144) at two concentrations (LC50 5 × 105 conidia mL−1 and LC100 1 × 107 conidia mL−1). We checked the survival of beetles exposed to PND or/and inoculated with B. bassiana, the expression of four antimicrobial peptides (AMPs), and finally how PND affects in vitro germination of fungus. The exposure to PND had no significant effects on the survival of either control or Bb-exposed beetles. In the mealworm beetle, upregulation of gene expression of the inducible AMPs Tenecin 1, 2, and 4 was observed in PND-treated beetles after inoculation with Bb, while the levels of the non-inducible AMP Tenecin 3 were similar between treatments. In conclusion, our findings demonstrate that admitted residual doses of currently used herbicides modify an important component of the inducible immune response of an insect. This did not translate into an effect on the survival to B. bassiana in our system. However, residual doses of the herbicide at 13 ppm may temporarily affect fungal germination. These results raise questions about the compatibility of bioinsecticides with synthetic pesticides and the effects of herbicide residues on host-pathogen interactions.

Herbicide residues in soil decrease microbe-mediated plant protection.

The residues of glyphosate are found to remain in soils longer than previously reported, affecting rhizosphere microbes. This may adversely affect crop and other non-target plants because the plant's resilience and resistance largely rely on plant-associated microbes. Ubiquitous glyphosate residues in soil and how they impact mutualistic microbes inhabiting the aboveground plant parts are largely unexplored. We studied the effects of herbicide residues in soil on Epichloë sp., which are common endophytic symbionts inhabiting aerial parts of cool-season grasses. In this symbiosis, the obligate symbiont subsists entirely on its host plant, and in exchange, it provides alkaloids conferring resistance to herbivores for the host grass that invests little in its own chemical defence. We first show decreased growth of Epichloë endophytes in vitro when directly exposed to two concentrations of glyphosate or glyphosate-based herbicides. Second, we provide evidence for a reduction of Epichloë-derived, insect-toxic loline alkaloids in endophyte-symbiotic meadow fescue (F. pratensis) plants growing in soil with a glyphosate history. Plants were grown for 2 years in an open field site, and natural herbivore infestation was correlated with the glyphosate-mediated reduction of loline alkaloid concentrations. Our findings indicate that herbicides residing in soil not only affect rhizosphere microbiota but also aerial plant endophyte functionality, which emphasizes the destructive effects of glyphosate on plant symbiotic microbes, here with cascading effects on plant-pest insect interactions.

Antagonistic Interaction between Phosphinothricin and Nepeta rtanjensis Essential Oil Affected Ammonium Metabolism and Antioxidant Defense of Arabidopsis Grown In Vitro.

Phosphinothricin (PPT) is one of the most widely used herbicides. PTT targets glutamine synthetase (GS) activity in plants, and its phytotoxicity is ascribed to ammonium accumulation and reactive oxygen species bursts, which drives rapid lipid peroxidation of cell membranes. In agricultural fields, PPT is extensively sprayed on plant foliage; however, a portion of the herbicide reaches the soil. According to the present study, PPT absorbed via roots can be phytotoxic to Arabidopsis, inducing more adverse effects in roots than in shoots. Alterations in plant physiology caused by 10 days exposure to herbicide via roots are reflected through growth suppression, reduced chlorophyll content, perturbations in the sugar and organic acid metabolism, modifications in the activities and abundances of GS, catalase, peroxidase, and superoxide dismutase. Antagonistic interaction of Nepeta rtanjensis essential oil (NrEO) and PPT, emphasizes the existence of complex control mechanisms at the transcriptional and posttranslational level, which result in the mitigation of PPT-induced ammonium toxicity and in providing more efficient antioxidant defense of plants. Simultaneous application of the two agents in the field cannot be recommended; however, NrEO might be considered as the PPT post-treatment for reducing harmful effects of herbicide residues in the soil on non-target plants.

Response of Mungbean to the Residual Toxicity of Herbicides Used in Wheat under Strip Tillage System

The residual effect of eight herbicides (Pendimethalin, Pretilachlor, Triasulfuron Ethoxysulfuron, Pyrazosulfuron Ethyl, Carfentrazone – ethyl, Carfentrazone – ethyl+ Isoproteuron, 2, 4 –D) used in wheat of Agronomy Field Laboratory during March to June 2014 was evaluated for mungbean. The eighteen herbicide treatment combinations of the eight herbicides were used in wheat. The experiment was conducted in Random Complete Block Design (RCBD) with three replications. The effect of herbicide residues on the mungbean was evaluated in term of germination, seedling root and shoot length, leaf chlorophyll content and seeding dry matter. The result showed that seedling establishment of mungbean was not adversely affected by the herbicides applied the previous wheat crop. Also, the residue of herbicides applied in strip-tilled wheat did not show any adverse effect on germination, shoot length and seedling dry matter of mungbean and even shoot growth of mungbean was not inhibited by the residue of those herbicides. The reason might be related to the half-life and rate of degradation of herbicides in soil. In addition, farmers can easily grow mungbean in a cropping pattern as a subsequent crop of wheat because the study ensures that tested herbicides did not show any adverse residual effect on the establishment of this succeeding crop. However, continuous use of same herbicide or different herbicides with same mode of action in the same land year after year is strictly prohibited. Also, the prudent use of chemical/herbicide is essential to fulfill the goals of conservation agriculture by having reducing detrimental environmental impact as well as reducing herbicide resistance development in crops.

Response of Sunflower to the Residual Toxicity of Herbicides Used in Wheat under Strip Tillage System

The residual effect of eight herbicides (Pendimethalin, Pretilachlor, TriasulfuronEthoxysulfuron, Pyrazosulfuron Ethyl, Carfentrazone – ethyl, Carfentrazone – ethyl+ Isoproteuron, 2, 4 –D) used in wheat of Agronomy Field Laboratory during March to June 2014 was evaluated for the sunflower. The eighteen herbicide treatment combinations of the eight herbicides used in wheat. The experiment was conducted in Random Complete Block Design (RCBD) with three replications. The effect of herbicide residues on the sunflower was evaluated in terms of germination, the seedling root and shoot length, leaf chlorophyll content and seeding dry matter. The result showed that the seedling establishment of sunflower was not adversely affected by the herbicides applied to the previous wheat crop.

Recent advances in mitigation methods for herbicide residues in the soil

In modern agriculture, with more emphasis on high input systems and the widespread application of herbicides has indubitably improved the crop production but has also resulted in inadvertent harm to the ecosystem. The increased awareness towards the adverse effects of herbicide residues on human health and environment resulted in a significant shift towards the mitigation strategies of herbicide residues in the soil as well as in the plants. Several approaches have been found to be utilized for mitigation of herbicide residues in the soil. The hazards from herbicide residues in the soil can be reduced by using low dosage chemicals, tillage operations, crop rotation, using proper nozzle and spraying technique and by using granular, foam, gel and encapsulated materials. Site specific application using variable rate applicator, enhancement of herbicide degradation through bio-stimulation, use of non-phytotoxic oil, adjuvants, surfactants, adsorbents, protectants, antidotes, safeners, biochar, etc. are various other effective ways for mitigation of herbicide residues in the soil. Biochar as an amendment to agricultural soils has been found to increase the bioavailable water, builds soil organic matter, enhances nutrient cycling, lowers bulk density, and can provide shelter for beneficial soil microorganisms. Biochar prevents the mobilization of herbicide residues in soil due to its sorption property and hence helps the crop to escape toxicity. Carbon based nano-absorbents such as carbon nanotubes (CNTs) represents a new class of nanomaterial and has been shown to have good potential in removal of various types of herbicide residues in the soil. Graphene is another carbon nanomaterial that has tremendous potential in water purification as well as in various fields due to its unique physical and chemical properties. Nanocrystalline metal oxides such as ferric oxides, manganese oxides, aluminium oxides, titanium oxides, magnesium oxides and cerium oxides are highly effective adsorbents for a broad range of herbicides. These nanocrystalline metal oxides do not only adsorb but also actually annihilate many chemical hazards by converting them to much safer by-products. The amalgamation of bioaugmentation and bio-stimulation along with organic matter addition might be a promising technology for biodegradation of herbicides in soil.

Herbicides act as restrictive factors in rice-watermelon rotation

Paddy-upland rotation, as a popular cultivation mode in many Asian countries, could largely increase land use efficiency and its productivity. In recent years, watermelon production is badly impaired by unknown factors that result in watermelon malformed roots in rice-watermelon rotation area. In this study, we examined the effects of several herbicides, which are often used for the weed control in rice season, on the growth of succeeding culture of watermelon. The effects of four different herbicides (penoxsulam, bensulfuron-methyl, chylapof-butyl and fhiroxypyr) with different concentrations at 1, 10, and 100 ppb, were investigated on three cucurbitaceae crops of watermelon, squash, and bottle gourd. All species were severely affected in plant growth by penoxsulam and bensulfuron-methyl herbicides at as low as 10 ppb after one week, whereas there was no obvious toxic effect of chylapof-butyl and fhiroxypyr treatments on plant growth even after two weeks. Among the three cucurbitaceae crops, watermelon showed the highest sensitivity to herbicide exposure, and the root tip ultrastructure micrograph further conformed the sensitivity of watermelon to herbicides. Moreover, the expression of auxin and cytokinin response factors suggested that plant hormones, auxin and cytokinin, play important roles in root growth and development under herbicide stress. In conclusion, we postulated that the residues of herbicides from application in rice production is one of the major barriers for successful production of watermelon crop. The present study provides new insights for avoiding the detrimental effects of herbicide residues in soil and improving watermelon production in sustainable rice-watermelon rotation cultivation mode.

Assessment of 14C-prosulfocarb dissipation mechanism in soil after amendment and its impact on the microbial community

Adding organic amendments to soil could modify the bioavailability of herbicides and lead to changes in the microbial community’s activity and structure. The objective here was to study the dissipation and total mass balance of 14C-labeled prosulfocarb applied at two rates (4 and 10 mg kg-1) in unamended and green compost (GC)-amended soil. Soil dehydrogenase activity (DHA) and phospholipid fatty acid (PLFA) profile analysis were determined to evaluate the effect of herbicide residues on microbial community's activity and structure over the dissipation period. The dissipation rate of prosulfocarb decreased after soil amendment due to higher herbicide adsorption by the amended soil. The 50% dissipation time (DT50) increased 1.7 times in the unamended soil when the concentration of prosulfocarb increased 2.5 times. The mass balance results indicate that the sum of water and organic extractable fractions represented the highest amounts up to the dissipation of 50% 14C-prosulfocarb. The 14C-herbicide was then mainly mineralized (up to 11%-31%) or formed non-extractable residues (up to 35%-44%). The amount of 14C-prosulfocarb residues extracted with methanol was slightly higher in amended soils than in unamended ones. 14C-prosulfocarb mineralization was higher in unamended soils than in amended ones. The formation of non-extractable residues was continuous, and increased over time. Soil DHA decreased in the unamended soil and was maintained in the GC-amended soil at the end of the assay. The microbial structure was barely disturbed over the prosulfocarb degradation process, although it was clearly influenced by the application of GC. The results obtained reveal the influence organic amendment has on herbicide bioavailability to decrease its biodegradation and buffer its impact on the soil microbial structure.

Emerging Challenges and Opportunities for Education and Research in Weed Science.

In modern agriculture, with more emphasis on high input systems, weed problems are likely to increase and become more complex. With heightened awareness of adverse effects of herbicide residues on human health and environment and the evolution of herbicide-resistant weed biotypes, a significant focus within weed science has now shifted to the development of eco-friendly technologies with reduced reliance on herbicides. Further, with the large-scale adoption of herbicide-resistant crops, and uncertain climatic optima under climate change, the problems for weed science have become multi-faceted. To handle these complex weed problems, a holistic line of action with multi-disciplinary approaches is required, including adjustments to technology, management practices, and legislation. Improved knowledge of weed ecology, biology, genetics, and molecular biology is essential for developing sustainable weed control practices. Additionally, judicious use of advanced technologies, such as site-specific weed management systems and decision support modeling, will play a significant role in reducing costs associated with weed control. Further, effective linkages between farmers and weed researchers will be necessary to facilitate the adoption of technological developments. To meet these challenges, priorities in research need to be determined and the education system for weed science needs to be reoriented. In respect of the latter imperative, closer collaboration between weed scientists and other disciplines can help in defining and solving the complex weed management challenges of the 21st century. This consensus will provide more versatile and diverse approaches to innovative teaching and training practices, which will be needed to prepare future weed science graduates who are capable of handling the anticipated challenges of weed science facing in contemporary agriculture. To build this capacity, mobilizing additional funding for both weed research and weed management education is essential.

Effect of herbicide residues on fall-seeded cover crops influence soil aggregate stability and mineral N

With increasing public emphasis on sustainable food production, cover crops (CC) integration into conventional production systems is gaining growers’ interest. However, herbicide residue effects on...

Effect of Herbicide residues on Soil Microorganisms in Turmeric

Field investigation were undertaken to evaluate the integrated weed management with pre and post emergence herbicides in turmeric at the Agricultural Research Station, Bhavanisagar of Tamil Nadu Agricultural University, during kharif season of 2012 and to elucidate information on bacterial, fungal and actinomycetes population due to the effect of herbicide residues. The bacterial, fungal and actinomycetes populations were recorded at 3, 15, 25, 50 and 75 DAP. The experiments were laid out in Randomized block design with three replications. The treatments comprised of different weed management practices wherein PE herbicides viz ., metribuzin 0.7 kg ha ‑1 , pendimethalin 1.0 kg ha ‑1 and atrazine 0.75 kg ha ‑1 followed by either POE fenoxaprop 67 g ha ‑1 + metsulfuron 4 g ha ‑1 (Tank mix) on 45 DAP or HW on 45 and 75 DAP or straw mulch 10 t ha ‑1 on 10 DAP + HW on 75 DAP, all PE oxyfluorfen 0.30 kg ha ‑1 , PE oxadiargyl 0.25 kg ha ‑1 , POE glyphosate 1.03 kg ha ‑1 and 1.54 kg ha ‑1 on 25 DAP followed by HW on 45 and 75 DAP, HW on 25, 45 and 75 DAP and unweeded check were imposed. In both the experiments, observations were recorded on soil microorganisms viz., populations of bacterial, fungal and actinomycetes were observed at different days after planting of rhizome. In this experiments showed herbicide application of PE metribuzin 0 .7 kg ha -1 , PE pendimethalin 1.0 kg ha -1 , PE atrazine 0.75 kg ha -1 ,PE oxyfluorfen 0.3 kg ha -1 and PE oxadiargyl 0.25 kg ha -1 recorded significantly lower microbial population immediately after herbicide spraying (3 DAP) than the treatments not having any herbicides and thereafter increased.

Effects on succeeding crops

Effects on succeeding crops

Effect of herbicide residues in a sandy loam on the growth, nodulation and nitrogenase activity (C2H2/C2H4) of Trifolium subterraneum

The herbicides 2,4-D, amitrole, atrazine, diclofop-methyl, diquat, paraquat and trifiluralin were applied at rates of 0, 2, 5 and 10 μg ai. g−1 to a sandy loam soil and allowed to degrade for 120 days. After this period, subterranean clover seedlings were transplanted into treated soil and the effect of herbicide residues on plant growth, number of nodules formed and nitrogenase activity was investigated. At all rates of atrazine and chlorsulfuron, and at all rates of amitrole in excess of 2 mg ai g−1 of soil, sufficient herbicide remained to be lethal to the seedlings. When amitrole was applied at the rate of 2 mg ai g−1 of soil, plant growth, nodulation and nitrogenase activity of plants were reduced. Residues of diquat reduced all plant parameters studied while, residues of 2,4-D reduced plant growth and nodule formation, but plant nitrogenase activity was unaffected. Residues of trifluralin had no effect on plant growth parameters but the number of nodules formed per plant was reduced. Residues of paraquat and diclofop-methyl had no effect on any of the plant parameters studied.

METSULFURON USE IN BARLEY AND RESIDUAL EFFECT ON SUCCEEDING CROPS

Experiments conducted over 4 yr (1982–1985) determined the efficacy of metsulfuron for use in spring barley (Hordeum vulgare L. ’Volla’) and effects of herbicide residues on crops grown the next season. Barley tolerated metsulfuron at rates up to 72 g a.i. ha−1 with no significant effects on yield but 1000-kernel weight was significantly reduced in two of the three barley crops grown. Control of lamb’s-quarters (Chenopodium album L.) and low cudweed (Gnaphalium uliginosum L.) was acceptable and that of corn spurry (Spergula arvensis L.) and shepherd’s-purse (Capsella bursa-pastoris (L.) Medic.) better than the standard MCPA amine treatment. There was no significant effect on marketable and total yield of rutabaga (Brassica napobrassica Mill.) or potato (Solanum tuberosum L.) and none on total yield of silage corn (Zea mays L.) when each was grown the season after metsulfuron use. Reductions in corn root growth were noted in bioassay tests as late as 120 d after metsulfuron application but the lack of effects on yields of succeeding crops would indicate that the remaining residues were broken down or diluted by plowing and working the soil.Key words: Metsulfuron, barley, potato, rutabaga, silage corn, persistence