Phytotoxicity Symptoms Research Articles

Use of aqueous plant extracts to reduce profenofos residues in the leaf of mustard (Brassica juncea L.) and suppression of the grasshopper population

Profenofos is an active ingredient from the organophosphate group which residue is often found in various fresh and processed vegetable products. This study aimed to assess the use of aqueous plant extracts of Sapindus rarak seeds, Luffa acutangula peel and Centella asiatica leaves to reduce profenofos residues in leaf of mustard and to evaluate their performance in suppressing the grasshopper populations. S. rarak seeds, L. acutangula peels and C. asiatica leaves were dried and filtered using a 100 mesh sieve. A total of 30 gm samples of each ingredient were mixed with 1000 ml of water and blended at 800 rpm, then filtered using 100 mesh sieve before use. The field experiment was performed by spraying profenofos pesticide with a concentration of 3 ml l-1 at a dose of 30 ml per plant. Two days after the profenofos application, the plants were sprayed with the aqueous plant extracts. Twenty-four hrs aqueous plant extracts application, pesticide residues were detected by the UPLC-MS/MS machine. The phytotoxicity test results showed that the use of aqueous plant extracts at a dose of 30 ml per plant did not cause any phytotoxic symptoms. Furthermore, in the field experiment, the control plants showed a residual value of 2407.62 ng g-1. Results of UPLC-MS/MS showed that the residual value of profenofos in PL treatment (aqueous extract of S. rarak seeds) was 1502.05 ng g-1, the recorded residual value in the PP treatment (aqueous extract of C. asiatica leaves) was 1316.27 ng g-1 and the residual value in the PG treatment (aqueous extract of L. acutangula peels) was 660.71 ng g-1. In the treated plants, the residual value decreased from 37.48% to 72.55%. Furthermore, the number of grasshoppers after the PL treatment decreased and was significantly different from the control. This study provides new information that aqueous plant extracts can reduce the residue of profenofos and suppress the population of grasshoppers in the mustard leaf.

Bioefficacy, environmental safety and synergistic impacts of biorational formulations against whitefly, leafhopper and blister beetle in organic okra ecosystem

AbstractWhitefly (Bemisia tabaci Gennadius), leafhopper (Amrasca biguttula biguttula Ishida) and large yellow-banded blister beetle (Mylabris phalerata) cause considerable damage to okra, especially under organic farming. Thus, the present study was carried out to test the bioefficacy and environmental safety of six naturally derived components [indigenous water plant extracts, i.e. chilli (Capsicum annum), garlic (Allium sativum L.) and neem (Azadirachta indica A. Juss.) along with cow urine in three different combinations, one commercial botanical (azadirachtin 0.15%), and two formulated entomopathogenic fungi (Verticillium lecanii and Beauveria bassiana)] on aforesaid pests for two consecutive years at field scale. In addition to this, the eco-toxicological effect of naturally derived components was also studied on natural enemies’ populations, viz. spiders and coccinellids. Quaternary mixture application of chilli, garlic, neem leaf and cow urine (CGNC) at 10% w/v was found effective in reducing leafhoppers (94.6%), whiteflies (95.2%) and blister beetle (94.6%) over control. Okra treated with CGNC produced a higher marketable fruit yield (18.44 mg/ha) than those of other treatments. It was also observed that the application of CGNC had no phytotoxic symptoms on okra plants. Application of CGNC was found safer to the natural enemy's population (spiders and coccinellids). Thus, the study suggests that CGNC can be considered as a potential source for managing the population of whitefly, leafhopper and blister beetle without affecting the ecology of natural enemies and it could be a viable eco-friendly option in organic okra production for ensuring food safety and healthy environment.

Biofumigation With Pellets of Defatted Seed Meal of Brassica carinata: Factors Affecting Performance Against Phytophthora nicotianae in Pepper Crops

Phytophthora nicotianaeis the pathogen that causes root and crown rot disease in open field paprika pepper crops of Extremadura (central-western Spain). A field experiment was established during spring, a period compatible with the pepper crop cycle in this region, to evaluate the effects of biofumigation with pellets ofBrassica carinatadefatted seed meal, at the rate recommended by the manufacturer (3 tons ha−1), on the survival and infectivity ofP. nicotianaechlamydospores inoculum. Furthermore, three biofumigant rates (3, 6, and 20 tons ha−1) were assayed in laboratory experiments with natural soil inoculated with chlamydospores. In the field trial, the incorporation of pellets at 3 tons ha−1did not produce remarkable changes in soil enzyme activity or soil properties. In both the field and laboratory tests, survival and infectivity in the biofumigated treatment at 3 tons ha−1did not differ from those in the untreated control. On the contrary, the same rate added to autoclaved soil completely suppressed the inoculum, suggesting that the soil microbiota degradesB. carinatapellets before being effective againstP. nicotianae. Increasing the recommended rate to 6 tons ha−1decreased inoculum survival in the laboratory test and 20 tons ha−1completely inhibited the inoculum, although the economic value of such a high rate application is a factor to be assessed. In phytotoxicity tests on radish and white mustard seeds with several concentrations (100, 50, 25, 10, 5, and 0%) ofB. carinatapellets solution, no phytotoxic effect was observed with the two lowest concentrations, and no symptoms of phytotoxicity were found in the bioassays of pepper plants.

Bioaccumulation of Lead by Pepper Elder (Peperomia pellucida (L.) Kunth) in a Lead-Contaminated Hydroponic System

Lead (Pb) has become one of the most common heavy metal contaminants, demanding research on economical remediation approaches with minimal ecological impacts. Pepper elder (Peperomia pellucida) is a fast-growing plant that can be a candidate for bioaccumulation and phytoremediation. In this study, the lead bioaccumulation of P. pellucida was assessed by determining the growth response and absorptive capacity of the plant. Plants were grown in hydroponic solution spiked with 500 mg/L of Pb for 28 days. Growth response, absorptive capacity and tolerance of plants grown in contaminated nutrient solution were determined in comparison with control plants. After 28 days of exposure, lead phytotoxicity symptoms such as wilting, chlorosis and necrosis were observed on some plants. The control plants recorded 3.08 g total dry weight (DW) compared to the 1.35 g in Pb-contaminated plants. The tolerance index (TI) of P. pellucida was at 43.40%. The plants were able to absorb lead, with the concentration of lead in the roots (158.6 µg/g) being greater than the concentration of the metal in the shoots (43.2 µg/g). Meanwhile, bioconcentration factor (BCF) and translocation factor (TF) values were recorded at 0.40 and 0.27, respectively. BCF criterion indicates that the plant is not suitable for phytoextraction, but TF value shows that the plant can be a potential excluder. The findings of the study show that P. pellucida accumulated considerable amount of lead within its tissues, indicating that the plants may be further exploited for their capacity to absorb heavy metals by tweaking several factors that may affect its bioaccumulation ability.

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.

Management of Powdery Mildew on Ninebark Using Sanitizers, Biorational Products, and Fungicides

Ninebark (Physocarpus opulifolius) is a popular ornamental shrub and considered a hardy and tough plant that can thrive in different environmental conditions and resist diseases. However, powdery mildew, caused by Podosphaera physocarpi, can severelyaffect ninebark, deteriorating the ornamental value and making them unmarketable. Only a few studies have been done in managing powdery mildew of ninebark. The current study focuses on evaluating and identifying effective products (sanitizers, biorational products, and fungicides) for the management of powdery mildew disease of ninebark. A total of 12 treatments, including nontreated control, were studied. The experiment was arranged in randomized complete block design with four-single ‘Mindia Coppertina®’ ninebark plant per treatment and repeated twice. Powdery mildew disease severity, growth parameters, and phytotoxicity were assessed in the study. All treatments significantly reduced the powdery mildew disease severity and disease progress [area under disease progress curve (AUDPC)] compared with the nontreated control. The treatments, such as azoxystrobin + benzovindiflupyr at 0.17 and 0.23 g·L–1 total active ingredients (a.i.) applied, chlorothalonil + propiconazole at 1.12 mL·L–1 total a.i. applied, azoxystrobin + tebuconazole at 0.11 and 0.16 g·L–1 total a.i. applied, and giant knotweed extract [Reynoutria sachalinensis (0.5 mL·L–1 total a.i. applied)] were the most effective treatments in reducing disease severity and disease progress in both trials. The treatments had no significant effects on the plant growth parameters such as height and width. In Expt. 2, azoxystrobin + benzovindiflupyr and hydrogen peroxide + peroxyacetic acid treated plants showed the low level of phytotoxic symptoms. The phytotoxicity of these two treatments in Expt. 2 could be related to higher environmental temperature during the experimental period.

Toxicity by metsulfuron-methyl in the establishment of the soybean crop submitted to seed treatment

Different management strategies and products can be adopted for weed control and seed treatment. This study evaluated the effect of metsulfuron-methyl application on the establishment of soybean (Glycine max Merril. L) at two herbicide application times and in response to micronutrient and amino acid seed treatment. The soybean seeds, cultivar Nidera 5909, were submitted to the following treatments: control (without treatment); amino acid; micronutrient 1 (a product containing amino acids from seaweed, cobalt, and molybdenum) and micronutrient 2 (a product containing amino acids from seaweed). The sowing periods occurred 15 days after the herbicide application or immediately after its application. We evaluated the emergence of seedlings at seven and 14 days after sowing (DAS), and the dry matters of roots and shoots at 14 and 21 DAS. The metsulfuron-methyl affected the seedling emergence at seven days after the sowing in seed treated with micronutrient 1 immediately after the herbicide application. At 21 DAS, a reduction in the dry mass of seedling roots was observed, which sowing occurred immediately after the application of the herbicide. The application of metsulfuron-methyl at sowing may damage the establishment and performance of soybean seedlings. Therefore, it is important to carry out sowing respecting the period of carryover effects from the herbicide, in order to prevent phytotoxicity symptoms to the soybean crop.

Effect of arsenic-contaminated irrigation water on growth and elemental composition of tomato and cabbage cultivated in three different soils, and related health risk assessment

This study was carried out to determine the effect of arsenic on tomato and cabbage cultivated in sand, sandy silt, and silt soil, and irrigated with water containing arsenic at concentrations 0.05 and 0.2 mg/L. Increasing arsenic in irrigation water did not affect the photosynthetic machinery. The chlorophyll content index increased in case of all soils and was dependent on the soil nitrogen, phosphorous, and plant biomass. Arsenic concentrations of 0.05 and 0.2 mg/L did not display any phytotoxic symptoms other than reduction in biomass in some cases. In cabbage, arsenic treatment of 0.2 mg/L increased the overall plant biomass production, while in tomato there was a decrease in aerial part and fruit biomass. The biomass production of both plants treated with different concentrations of arsenic, in the three soils was in the following order: silt > sand > sandy silt. Increase of arsenic in the irrigation water resulted in increase in arsenic concentration in the root and aerial part of both plants, at the same cultivation parameters. But tomato fruits displayed a decrease in arsenic accumulation with higher arsenic treatment. In both plants, the arsenic concentration in the plant parts changed in the following order: root > aerial part > fruit. Cabbage accumulated approximately twenty-fold more arsenic in the edible part (0.10–0.25 mg/kg DW) as compared to tomato (0.006–0.011 mg/kg DW) and displayed a good correlation with soil extractable arsenic. When cabbage was cultivated in three different soils applying the same irrigation water, it accumulated arsenic in the following order: sand > sandy silt > silt (p < 0.001 at 0.05 mg/L and p < 0.01 at 0.2 mg/L arsenic treatment). In tomato, the difference in arsenic accumulation among different soil types was highly significant (p < 0.001) but the accumulation pattern varied with the arsenic treatment applied. Sandy soil with the lowest total soil arsenic (4.32 mg/kg) resulted in the highest arsenic concentration in both plants. Among all soils and plants, the transfer factors and bioaccumulation factors were higher in sandy soil, and in cabbage. The estimated daily intake and hazard quotient values for arsenic were lower than 1 in all cases, implying no non-cancerous health risks at the arsenic concentrations applied in our study. Among nutrients only P showed a slight decline with increasing arsenic concentration while all other elements (Mg, K, Ca, S, Si, Fe, Mn, Cu, Zn) did not display any significant changes.

Evaluating the Effects of Acetic Acid and d-Limonene on Four Aquatic Plants

The foundation of most aquatic weed management programs in Florida is synthetic herbicides because many of these U.S. Environmental Protection Agency (USEPA)-registered products are effective, selective, and inexpensive compared with other strategies such as mechanical harvesting. However, stakeholders have expressed concern regarding their use and managers are interested in exploring alternative methods for aquatic weed control. To that end, we evaluated the efficacy, selectivity, and costs of the “natural” products acetic acid and d-limonene (alone and in combination with each other and citric acid) on the invasive floating plants waterhyacinth (Eichhornia crassipes) and waterlettuce (Pistia stratiotes), and the native emergent plants broadleaf sagittaria (Sagittaria latifolia) and pickerelweed (Pontederia cordata). These products, plus an industry-standard synthetic herbicide (diquat dibromide), were applied once as foliar treatments to healthy plants, which were grown out for 8 weeks after treatment to allow development of phytotoxicity symptoms. A 0.22% concentration of diquat dibromide eliminated all vegetation, but neither “natural” product alone provided acceptable (&gt;80%) control of floating weeds, even when applied at the maximum concentrations under evaluation (20% acetic acid, 30% d-limonene). Citric acid (5% or 10%) had no effect on the activity of acetic acid or d-limonene, but some combinations of acetic acid and d-limonene controlled floating weeds effectively without causing unacceptable damage to native plants. However, these treatments are much more expensive than the synthetic standard and managers would realize a 22- to 26-fold increase in product cost alone without factoring in other expenses such as additional labor and application time. Combinations of acetic acid and d-limonene may have utility in some areas where the use of synthetic herbicides is discouraged, but broad-scale deployment of this strategy would likely be prohibitively expensive.

Herbicide Tolerance of Sugarcane Genotypes to Post-emergence Application of Halosulfuron Methyl and Metribuzin: An Inadvertent Preliminary Assessment

Thirty-one sugarcane genotypes were planted in the experiment and post-emergence application of Halosulfuron Methyl 75% WG and Metribuzin 70% WP was carried out at the rate of 67.5 g and 1000 g a.i. per hectare on 42 days after planting (DAP). Lower leaves of some of the genotypes were found to show injuries on 5 days after spraying (DAS). Phytotoxicity was recorded in visual scoring scale of 0 to 10 at 7, 15, 21 and 30 DAS. Phytotoxicity rating of the 31 genotypes studied ranged between 0 and 4. Nine genotypes showed no visual injury and found tolerant, while eight genotypes showed moderate toxic effect (rating 4). All the genotypes (14 nos.) that showed phytotoxicity rating of 1 to 3 recovered visually (leaf injuries) except Co 06027 at 30 DAS, while all the genotypes that showed moderate phytotoxicity did not recover completely except Co 94008. The genotypes with Co 7201 and Co 775 as one of the parents showed phytotoxicity rating ranging from 1 to 4. The genotypes, Co 06030, Co 86032, Co 11015, Co 92005 and Co 09004 did not exhibit phytotoxicity symptoms, while their parent, CoC 671 exhibited phytotoxicity. Seven parental genotypes showed 100% probability of no herbicidal injury in their progenies and exhibited herbicidal tolerance from initial stage. Cane yield reduction (> 5%) was observed only in Co 8021, Co 94008 and Co 99006 with herbicide treatment over no herbicide application. The present study provides a preliminary information on the genetic variation among sugarcane genotypes for herbicide tolerance and their parental relationship, which could be utilized for the development of herbicide tolerant varieties for effective weed management in sugarcane agriculture.

Efficacy of tank mixtures of post-emergence herbicides in common bean

In common bean, the occurrence of weeds can cause significant reductions in the final grain yield. This study aimed to evaluate the efficiency of different herbicide trials, applied individually or in a mixture, in the management of common bean weeds. A randomized complete block was used, arranged in subdivided plots. The main plots consisted of three types of beans (Carioca Pérola cultivar, Black cultivar IPR Tuiuiu and one Red Bean strain VR20) and the subplots of different control modes, in four replications: hand weeding, fomesafen (250 g per hectare of ingredient active (g ha-1 of a.i.)), fomesafen (375 g ha-1 of a.i.), imazamox + bentazon (0,23 + 0,6g ha-1 of a.i.), imazamox + bentazon + fomesafen (0.23 + 0.6 + 125 g ha-1 of a.i.) and imazamox + bentazon + fomesafen (0.23 + 0.6 + 83 g ha-1 of a.i.). The following traits were evaluated during three seasons: weeds present in the area, phytotoxicity symptoms, and common bean grain yield. The data were analyzed using a variance analysis (F test), the means obtained were grouped by the Scott Knott test at 5 % probability. Differences in grain yield performance were observed between cultivars and crops season due to herbicide application. The most efficacy treatment for weeds was imazamox + bentazon + fomesafen (230 + 600 + 125 g ha-1 of a.i.), resulting in improved control and greater efficiency in avoiding grain yield losses.

A novel pre‐emergence herbicide (Diclosulam) as an environmentally friendly weed management option in peanut and its phytotoxicity evaluation

AbstractA two‐season field experiment was conducted to evaluate the efficacy of diclosulam compared with recommended doses of pendimethalin and oxyfluorfen for weed management in peanut. Persistence of diclosulam in oil, de‐oiled cake, haulm of peanut, and soil was also studied. Diclosulam 22 and 26 g a.i. ha−1, and a weed‐free check had a high pod yield due to more mature pods and their mass. Pre‐emergence application of diclosulam 26 g a.i. ha−1 provided better weed management and enhanced peanut growth and yield with high net returns. Phytotoxicity studies indicated that the diclosulam application did not cause any phytotoxic symptoms (vein clearing, epinasty, hyponasty, wilting, and injury) on leaf tips and leaf surface of peanut. Diclosulam residues in peanut viz. oil, de‐oiled cake, haulm, and soil were below the detection level after harvesting of peanut from the experimental field. Further, germination percentage and seed cotton yield of cotton crop cultivated after peanut were also not affected significantly.

Efficacy of pre-seeding application of two formulations of paraquat dichloride in managing weeds in dry direct-seeded rice

A field experiment was conducted at GBPUA&T, Pantnagar during Kharif (rainy) season of 2015 to evaluate and compare the efficacy of pre-seeding application, at 2 days before seeding (DBS), of two formulations of paraquat dichloride on weeds associated with dry direct-seeded rice (dry-DSR) and assess their possible phytotoxicity to rice crop. Two formulations of paraquat dichloride include: i. Sponsor sample (SS) (paraquat dichloride 45% SL) tested at 300, 450, 800, 1600 g/ha and ii. Commercially available paraquat dichloride market sample (MS) tested at 800 g/ha. The paraquat dichloride at 1600 g/ha provided 85–95% weed control efficiency at all crop growth stages. All the herbicidal treatments were found significantly superior over hand weeding twice [(before sowing and at 20 days after seeding (DAS)]. The highest grain yield (3.3 t/ha) was obtained with paraquat dichloride 1600 g/ha followed by 800 g/ha. No symptoms of phytotoxicity were observed on dry-DSR at any of the doses of both the formulations of paraquat dichloride applied two days before seeding rice. Paraquat dichloride (SS) efficacy at 1600 and 800 g/ha applied 2 DBS was at par with each other in effectively managing broad spectrum weeds in dry direct-seeded rice in Tarai water (lowland) region of Uttarakhand.

The influence of selected herbicides and their mixtures used with split application method on weed infestation growth and yield of onion

The studies carried out in the years of 2014–2017 at the Institute of Horticulture in Skierniewice were aimed to compare the biological effectiveness of foliar applied herbicides: oxyfluorfen, prosulfocarb, bromoxynil, pyridate and their mixtures, as well as assessment of suitability of these substances for weeds control in sowed onion. Herbicides were applied with the split application method, in three treatments, every 5–8 days from 1‒2 true leaves stage of onion or in two treatments from 2–3 leaves of onion. The studies assessed the effect of herbicides and their mixtures on the degree of weed damage, secondary weed infestation, selectivity, as well as onion growth, development and yield. The results showed that the greatest reduction of weeds and the highest yield, with slight, transient phytotoxicity symptoms, were obtained after 3 times spraying with oxyfluorofen in a mixture with bromoxynil. The weakest weed control and the lowest onion yield were obtained after applying oxyfluorfen in two treatments, in a mixture with pyridate.

Bioefficacy, phytotoxicity, safety to natural enemies and residues of cyantraniliprole 10 OD on potato (Solanum tuberosum L.) under open field condition

Two field experiments were conducted to evaluate the bioefficacy of cyantraniliprole 10 OD as foliar application against the major sucking pests and armyworm of potato, safety against natural enemies, phytotoxicity study and harvest time residue in/on potato tubers in open field condition. The results revealed that, cyantraniliprole 10 OD @ 90 and 75 g a.i. ha−1 recorded least mean population of sucking pests after two round of spray at ten days interval. The order of relative efficacy of test insecticides based on mean population of sucking pests were, cyantraniliprole 10 OD @ 90 g a.i. ha−1 = cyantraniliprole 10 OD @ 75 g a.i. ha−1 = cyantraniliprole 10 OD @ 60 g a.i. ha−1 > thiamethoxam 25 WG @ 25 g a.i. ha−1 = dimethoate 30 EC @ 200 g a.i. ha−1 > cyantraniliprole 10 OD @ 45 g a.i. ha−1 > untreated control. More than 90 per cent reduction of armyworm larval population was observed in cyantraniliprole 10 OD @ 90, 75 and 60 g a.i. ha−1 treatments. Though there was a sudden decline in the coccinellids population after spraying of cyantaniliprole 10 OD, it started increasing gradually. All the doses of cyantraniliprole 10 OD (75, 150 and 300 g a.i. ha−1) did not cause any noticeable phytotoxic symptoms on potato plants. Cyantraniliprole 10 OD at 90 and 75 g a.i. ha−1 recorded increased yield of 34.11 and 32.42% over untreated control. The residues of cyantaniliprole in the potato tubers collected from cyantraniliprole at 75 and 150 g a.i. ha−1 treated plots at the time of harvest recorded as below detectable level.

Study of Different Rates of Application of Mixture of Amidosulfuron and Iodosulfuron-Methyl-Sodium on Broadleaf Weed Infestation and Grain Yield of Soft Wheat

Aims: A soft wheat weed control trial was conducted in order to investigate the effect of mixture of Amidosulfuron and Iodosulfuron-methyl-sodium on controlling broadleaf weeds infestation in a soft wheat crop.&#x0D; Study Design: The experimental design was a random block with three replications. Each block contained 4 elementary plots, 3 plots of which are treated with three doses of mixture of Amidosulfuron and Iodosulfuron-Methyl-Sodium and one untreated control plot.&#x0D; Place and Duration of Study: Field experiments in Ouazzane region of Morocco. Laboratory measurements were carried out at weed research laboratory of INRA-CRRA Tangier. Morocco, between December 2016 and July 2017.&#x0D; Methodology: Treatments was applied at weed seedling stage. Three doses of mixture of Amidosulfuron and Iodosulfuron-methyl-sodium were applied. Observations were made 14, 28 and 56 days after application of herbicides (DAT). Observations concerned selectivity of applied treatments, percentage of weed density reduction, biomass reduction and soft wheat grain yield.&#x0D; Results: Results showed that treatments with mixture of 15 g/ha Amidosulfuron + 3.75 g/ha Iodosulfuron-methyl-sodium and 22.5 g/ha Amidosulfuron + 5.63 g/ha Iodosulfuron-methyl-sodium gave the best control of broadleaf weeds infestations and provided the best wheat grain yield. No phytotoxic symptoms were observed on soft wheat crop. Treatment with mixture of (15g/ha Amidosulfuron+ 3.75 g/ha Iodosulfuron-methyl-sodium) recorded 95.7±1.3%, and 98.5±0.5% respectively on weed density reduction, and weed dry biomass reduction. Treatment with mixture of (22.5 g/ha Amidosulfuron + 5.63 g/ha Iodosulfuron-methyl-sodium) recorded 98.5±0.5% and 98.8±0.3% respectively on weed density reduction and weed dry biomass reduction. Treatment with mixture of (7.5 g/ha Amidosulfuron + 1.88 g/ha Iodosulfuron-methyl-sodium) recorded the lowest efficacies 60.7±10.2% and 70.2±3.3% respectively on weed density reduction and weed dry biomass reduction. Plots treated with mixture of (15 g/ha Amidosulfuron + 3.75 g/ha Iodosulfuron-methyl-sodium) and (22.5 g/ha Amidosulfuron+ 5.63 g/ha Iodosulfuron-methyl-sodium) recorded the highest yields of 3.65±0.1 and 3.46±0.3 tons/ha respectively an increase exceeding 74% over the control.&#x0D; Conclusion: Mixture of (15 g/ha Amidosulfuron+ 3.75 g/ha Iodosulfuron-methyl-sodium) and (22.5 g/ha Amidosulfuron+ 5.63 g/ha Iodosulfuron-methyl-sodium) gave the best control of weed infestation in soft wheat and recorded the best grain yield. Therefore, mixture of (15 g/ha Amidosulfuron+ 3.75 g/ha Iodosulfuron-methyl-sodium) can be recommended in similar weed infestation in soft weed crop.

Ecotoxicity of oil sludges and residuals from their washing with surfactants: soil dehydrogenase and ryegrass germination tests

Oil sludge washing (OSW) with surfactants and co-solvents is used to recover the oil, and this process leaves some residuals (sediments and surfactant solution). Currently, there are no data on the ecotoxicological effects of these OSW residuals from different sludges. This study evaluated the toxicity of OSW residuals from washing four types of oil sludges with five surfactants (Triton X-100 and X-114, Tween 80, sodium dodecyl sulphate (SDS) and rhamnolipid) and a co-solvent (cyclohexane). The toxicity of the residuals was evaluated with the impact on the soil microbial dehydrogenase activity (DHA) and ryegrass (Lolium perenne) seed germination. There was a high DHA detected directly in the sludges and all OSW residual combinations, but this activity could not be attributed to the DHA itself but to some chemical interferences. The DHA was then tested in the soils amended with the OSW residuals to simulate a bioremediation scenario. There were no chemical interferences in this case. In general, the INTF concentrations were significantly higher at low concentrations, 1 and 5% (p < 0.01). There were no significant differences in the DHA at high concentrations of OSW residuals (10, 25 and 50%) which implied that the concentration of the contaminants is not directly proportional to the levels of ecotoxicity. Unexpectedly, the INTF values of the 10, 25 and 50% rhamnolipid-OSW residuals were significantly lower than the Triton X-100 residuals. The ryegrass germination rates were higher than 70% with no apparent phytotoxicity symptoms in the seedlings. Particularly, there was a highly significant negative effect of the residuals on the germination rates at high concentrations (p < 0.01). Given that the extractable petroleum hydrocarbon (EPH) concentrations in the OSW residual-amended soils in both DHA and germination tests were very low (13–21 ppm), other co-contaminants could be contributing to the toxicity. These findings implied that biotreatment techniques can be applied to treat the OSW residuals if necessary.

Assessment of biodegradable chelating agents in the phytoextraction of heavy metals from multi–metal contaminated soil

A pot incubation experiment under natural conditions was designed to investigate the effects of three biodegradable chelating agents, namely; the [S,S]-isomer of ethylenediamine disuccinate (EDDS), citric acid (CA), and tetrasodium N,N-Bis(carboxymethyl)-L-glutamate acid (GLDA), on two plant species (Brassica juncea and Brassica rapa) in terms of plant foliar growth, dry matter yield, and heavy metal (HM) accumulation. Both plant species exhibited diminished growth and symptoms of phytotoxicity under HM stress. The application of EDDS and CA affected plant foliar growth, biomass production, and led to the development of chlorotic lesions on leaves. EDDS and CA also decreased the shoot length by 38.5% and 45.2% in B. juncea, and 60.1% and 100% in B. rapa, respectively. In contrast, GLDA relieved HM stress by significantly increasing plant growth (P > 0.05) and was shown to be well tolerated (tolerance index [TI]; B. juncea = 99% and B. rapa = 123%). Among both plants, B. juncea displayed the ability to accumulate a wider range of HMs at higher concentrations. Amongst the three chelators, EDDS induced the highest bioconcentration (BCF) of Pb (2.45), Zn (2.68), and Cd (3.36) while CA achieved better results for Ni (4.01) and Cr (1.45). However, the current results showed that even with the application of chelating agents, HMs were predominantly accumulated in roots and translocation factor was generally <1. The findings of this investigation emphasize that chelate–assisted phytoextraction with Brassica spp. is highly limited in multi–metal settings, making it an unsuitable option for severely contaminated sites.

Millettia pinnata and Sesamum indicum seed oil based green pesticide formulations for the management of tea red spider mite, Oligonychus coffeae Nietner (Acari: Tetranychidae)

Red spider mite, Oligonychus coffeae is an economically important pest of tea in major tea producing countries. The present study aimed to evaluate the efficacy of five plant oil based formulations viz.., SOF, MOF, SMOF1:1, SMOF3:2 and SMOF2:3 prepared by considering individual as well as combination of Sesamum indicum and Millettia pinnata seed oil at different ratios of 1:0, 0:1, 1:1, 3:2 and 2:3, respectively against eggs and adults stages of O. coffeae. The experiments were done following leaf dip and direct spray methods. LC50 values of different formulations viz.., SOF, MOF, SMOF1:1, SMOF3:2 and SMOF2:3 against O. coffeae (adult females) were 3807.10 ppm, 4672.88, 3248.98, 4155.57 and 4610.55 ppm, respectively. The formulations also showed significant ovicidal and growth inhibitory activity against O. coffeae. Two season field bio-efficacy results indicated that the formulations are highly effective against O. coffeae and were superior to commonly used chemical acaricide, ethion 50EC. No phytotoxic symptoms were observed on tea leaves treated with these formulations. Black tea manufactured from tea shoots treated with these oil formulations were free from any taint and scored good (6–8 in 10 scale) in organoleptic test. The data suggests that plant oils of M. pinnata and S. indicum seeds alone and in combinations have potential to manage tea red spider mite in the field and can be recommended for eco-friendly management of mite pest in tea.

2,4-D em videiras: estudo de caso no Município de Jaguari-RS, estado do Rio Grande do Sul, Brasil

Atualmente plantas de videira no município de Jaguari, localizado na região centro-oeste do estado do Rio Grande do Sul - Brasil, apresentam sintomas de fitotoxidez, possivelmente oriundos da aplicação de agrotóxicos em áreas de produção agrícola. A uva é um produto de grande valor econômico, social e cultural para a região. Neste sentido a Lei Municipal N° 3.163 restringe o uso de herbicidas derivados da composição química 2,4-D (diclorofenoxiacético) em todo o território do município de Jaguari no período de 15 de setembro a 15 de março de cada ano agrícola, independente da modalidade de sua aplicação. Portanto, o objetivo deste trabalho foi identificar e quantificar resíduos de 2,4-D nas folhas de videira pelo método QuEChERS e análise por HPLC-MS/MS. A coleta das amostras foi realizada em seis propriedades localizadas dentro do perímetro delimitado pela Lei Municipal N° 3.163. O período de amostragens foi semanal de 29/09/2017 a 06/12/2017, perfazendo um total de 62 amostras. Foram coletadas folhas de videiras e armazenadas em sacos plásticos devidamente identificados e encaminhados para o Laboratório de Análises de Resíduos e Pesticidas (LARP), na Universidade Federal de Santa Maria (UFSM). Durante o período de amostragem observou-se problemas de fitotoxidez das plantas. Comprovou-se a presença de resíduos do herbicida em 69% das amostras, concluindo-se que a deriva do produto pode ser a causa dos danos nas videiras apontados pelos produtores de Jaguari.