Development and pathogenicity analysis of full-length infectious cDNA clones of citrus yellow mottle-associated virus in citrus plants

Citrus yellow mottle-associated virus(CiYMaV)belonging to the subgenus Mandarivirus within the genus Potexvirus,was first identified in 2018 from Pakistan(CiYMaV-PK),where it is endemic in several regions.Here,three full-length cDNA clones(pCiYMaV-FL-1,pCiYMaV-FL-18,and pCiYMaV-FL-22)corresponding to the genomic RNA of CiYMaV were constructed and then agroinfiltrated on Chandler pummelo(Citrus grandis)seedlings using the vacuum infiltration method.All the inoculated plants developed severe vein yellowing,leaf mottling,and dwarfing symptoms by 40 days post-infiltration(dpi).The results of a direct tissue blot immunoassay and reverse transcription polymerase chain reaction detection showed 94.7–100%infection rates of pCiYMaV-FL at 60 dpi.Despite there being no observed difference among the three clones in the severity of symptom,pCiYMaV-FL-22 showed the highest accumulation levels of viral RNA and coat proteins.Moreover,pCiYMaV-FL-22 successfully infected seven other citrus varieties and induced symptoms in five of them.Transmission electron microscopy identified the presence of filamentous virus particles in extracts from systemic leaves of the plants infected with pCiYMaV-FL-22 at 6-months post-infiltration.Taken together,the results indicate that Koch's postulates were fulfilled for CiYMaV in citrus plants.This is the first report of full-length infectious cDNA clones of CiYMaV,and thus,the data provide a basis for further study of the molecular mechanisms of virus infection and the development of a viral vector to express foreign genes in citrus plants.

Toxic and Antifeedant Effects of Different Pesticidal Plant Extracts against Beet Armyworm (Spodoptera exigua)

The beet armyworm(BAW),Spodoptera exigua(Lepidoptera:Noctuidae)is a highly destructive pest of vegetables and field crops.Management of beet armyworm primarily relies on synthetic pesticides,which is threatening the beneficial community and environment.Most importantly,the BAW developed resistance to synthetic pesticides with making it difficult to manage.Therefore,alternative and environment-friendly pest management tactics are urgently required.The use of pesticidal plant extracts provides an effective way for a sustainable pest management program.To evaluate the use of pesticidal plant extracts against BAW,we selected six plant species(Lantana camara,Aloe vera,Azadirachta indica,Cymbopogon citratus,Nicotiana tabacum,and Ocimum basilicum)for initial screening experiment.Four out of six plant species such as A.indica,N.tabacum,C.citratus and O.basilicum showed promising mortality of more than 50%.Therefore,we selected these four plant extracts for the subsequent experiments.Through contact bioassay,A.indica showed high mortality 66.63%,followed by the N.tabacum 53.33%,at 10%w/v concentration.Similarly,N.tabacum showed the highest mortality rate,66%at 10%w/v concentration,followed by the A.indica 46%through feeding bioassay.Furthermore,the feeding deterrence assay showed that C.citratus had a high antifeedant index(−50)followed by A.indica(−39),and N.tabacum(−28).In living plant assay,the N.tabacum extract showed a low mean damage score 3.6 on living cotton plant followed by C.citratus 4.5 and A.indica 5.5.Hence,extracts of three plant species provided promising results against the BAW,which can minimize the use of synthetic chemicals,particularly for small landholding farmers.Further studies are also required to evaluate the effects of these plant extract against BAW on cotton plants under field conditions to optimize the further use.

Ecological Fitness of Non-vector Planthopper Sogatella furcifera on Rice Plants Infected with Rice Black Streaked Dwarf Virus

We evaluated the effects of rice black streak dwarf virus （RBSDV）-infested rice plants on the ecological parameters and its relevant defensive and detoxification enzymes of white-backed planthopper （WBPH） in laboratory for exploring the relationship between RBSDV and the non-vector planthopper. The results showed that nymph survival rate, female adult weight and fecundity, and egg hatchability of WBPH fed on RBSDV-infested rice plants did not markedly differ from those on healthy plants, whereas the female adult longevity and egg duration significantly shortened on diseased plants. Furthermore, significantly higher activities of defensive enzymes （dismutase, catalase and peroxidase） and detoxification enzymes （acetylcholinesterase, carboxylesterase and glutathione S-transferase） were found in WBPH adults fed on infected plants. Results implied that infestation by RBSDV increased the ecological fitness of non-vector planthopper population.

Analysis of sex pheromone production and field trapping of the Asian corn borer(Ostrinia furnacalis Guenée)in Xinjiang,China

Identifying the sex pheromone systems of local pest populations facilitates their management,especially for moth species that show significant geographic variation in sex pheromone communication.We investigated the pheromone production and behavioral responses of the Asian corn borer(Ostrinia furnacalis Guenée;ACB)in Xinjiang,China.The ACB produces three compounds:(Z)-12-tetradecenyl acetate(Z12-14:Ac)and(E)-12-tetradecenyl acetate(E12-14:Ac)which are two sex pheromone compounds,and n-tetradecyl acetate(14:Ac)which has variable roles in mediating behavioral responses.The ratios of these three compounds produced in female gland are geographically distinct among different populations.Quantitative analysis of pheromone production showed that the proportions of Z12-14:Ac in the E/Z isomers(i.e.,Z and E12-14:Ac)and the proportions of 14:Ac in the ternary blend respectively averaged 60.46%(SD=5.26)and 25.00%(SD=7.37),with their probabilities normally or near-normally distributed.Trapping experiments in a cornfield indicated that deploying the E/Z isomers and the three compounds in rubber septa close to their gland ratios yielded the most captured males,while other ratios that deviated from the gland ratios showed reduced field captures.The ternary blend was significantly more attractive to males than the E/Z isomers in the field,indicating a functional role of 14:Ac as the third pheromone component used by the local population.Additionally,the dose-response test demonstrated that the application of the three compounds at dosages between 200 and 350μg attracted significantly more males compared to other dosages.Therefore,the characterization of this local ACB pheromone system provides additional information about its geographic variation and serves as a basis for optimizing the pheromone-mediated control of this pest in Xinjiang.

Fusarium wilt of banana:Current update and sustainable disease control using classical and essential oils approaches

Fusarium species were reported to produce biofilms.Biofilms are superficial societies of microbes bounded and endangered by being situated or taking place outside a cell or cells.The most destructive fungal diseases caused by phytopathogens are as a result of biofilms formation.Fusarium wilt of banana(Panama disease)is caused by a soil-borne pathogen called Fusarium oxysporum f.sp.cubense.Fusarium oxysporum occurs in a form of a species complex(FOSC)which encompasses a crowd of strains.Horizontal genetic factor transfer may donate to the observed assortment in pathogenic strains,while sexual reproduction is unknown in the FOSC.Fusarium wilt is a notorious disease on several crops worldwide.Yield loss caused by this pathogen is huge,and significant to destroy crop yields annually,thereby affecting the producer countries in various continents of the world.The disease is also resistant to various synthetic chemical fungicides.However,excessive use of synthetic fungicides during disease control could be lethal to humans,animals,and plants.This calls for alternative eco-friendly management of this disease by targeting the biofilms formation and finally suppressing this devastating phytopathogen.In this review,we,therefore,described the damage caused by Fusarium wilt disease,the concept of filamentous fungal biofilms,classical control strategies,sustainable disease control strategies using essential oils,and prevention and control of vegetables Fusarium wilt diseases.

Influence of seven levels of chemical/biostimulator protection on amino acid profile and yield traits in wheat

Biostimulators combined with pesticides can reduce the need for chemical crop protection to yield healthy wheat with high grain quality and nutritional value.The goal of this four-year field study was an assessment of the effects of seven levels of sulfonylurea herbicide,morpholine and triazole fungicides,and humic biostimulator protection on concentrations of 20 amino acids(AAs)and on yield parameters under diverse climatic conditions.Application of pesticides and biostimulators reduced amino acid concentrations.Sulfonylurea applied alone reduced AAs least.Chemical(herbicide+fungicide)protection or its combination with humic biostimulator were the most effective strategies for increasing yield,thousand-kernel weight,spike number,grain surface area,and wet gluten.Reduced dosages of fungicides showed effects on AA content and crop parameter values similar to those of the recommended dosages of fungicides and are in line with the European Commission’s “From Farm to Fork”strategy.Humic biostimulators as agents supporting pesticide protection should be optimized for wheat growth stage to achieve the most desirable wheat parameters and implemented in agricultural practice.

Vegetative Compatibility and Virulence Diversity of Verticillium dahliae from Okra (Abelmoschus esculentus) Plantations in Turkey and Evaluation of Okra Landraces for Resistance to V. dahliae

Forty-four V.dahliae isolates were collected from symptomatic vascular tissues of okra plants each from a different field in eight provinces located in the eastern Mediterranean and western Anatolia regions of Turkey during 2006-2009.Nitrate-nonutilizing(nit)mutants of V.dahliae from okra were used to determine heterokaryosis and genetic relatedness among isolates.All isolates from okra plants were grouped into two vegetative compatibility groups(VCGs)(1 and 2)and three subgroups as 1A(13.6%,6/44),2A(20.5%,9/44)and 2B(65.9%,29/44)according to international criteria.Pathogenicity tests were performed on a susceptible local okra(A.esculentus)landrace in greenhouse conditions.All isolates from VCG1A and VCG2B induced defoliation(D)and partial defoliation(PD)symptoms,respectively.Other isolates from VCG2A gave rise to typical leaf chlorosis symptoms without defoliation.The obtained data showed that the virulence level of V.dahliae isolates from okra was related to their VCG belongings.Eighteen okra landraces from diverse geographical origins were screened for resistance to VCG2B and VCG1A of V.dahliae.The results indicated that all landraces were more susceptible to highly virulent VCG1A-D pathotype displaying D or PD symptoms depending on their susceptibility levels with a mean disease severity index of 3.52 than to less virulent VCG2B-PD pathotype of V.dahliae displaying PD and ND symptoms with a mean disease severity index of 2.52.Significant differences were observed among the landraces;however,none of them exhibited a level of resistance.Okra landraces;Çorum,Hatay Has and Sanlıurfa displayed the lowest level of susceptibility or little tolerance to both D and PD pathotypes.VCG2B of PD was prevailing in the surveyed areas and VCG1A of D was the most virulent of the VCGs identified.Introduction of resistant genotypes to Turkish okra germplasm from different sources and breeding new resistant okra cultivars are critical for the sustainability of okra production.

Census Ethnobotanical Study of Some Plants Used in Traditional Medicine in the City of Meknes

An ethnobotanical survey was conducted in the city of Meknès over a period of two years, from 2009 to 2011 with 1000 people (615 women, 385 men). Through the questionnaire, schedules were established to collect information on the use of therapeutic medicinal plants by the local population. This research has focused primarily on the general population, herbalists and healers. The present investigation has enumerated 194 species distributed in 165 genera and 72 families. The most represented families are Lamiaceae (18%), the Aseraceae, (17%), the Apiaceae (14%) and the Fabaceae (10%). The results of the survey show that 54% of individuals use both herbal medicine and modern medicine, 26% of individuals use herbs and 20% use modern medicine. We are interested in the use of plants in different ages and sexes. We report that 31% of the population is aged between 51 and 60 years, 29% between 41 and 50 years, 23% between 31 and 40 years, 10% between 21 and 30 years, 3% less than 20 years and 4 % > 60 years. We note the predominance of women over men. Women use up to 61% against 39% of men. The analysis of our results shows that herbal medicine takes a place in the self-medication of the population studied. However, we emphasize an important point: Ignorance of toxic plants, in fact, only 19% of the target population recognizes these plants.

Efficacy of Groundnut Oil, Wood Ash, Sand and Some Plants Powders against Callosobruchus chinensis in Cowpea Seeds

This study was conducted under Laboratory of Plant Protection Department, Faculty of Natural Resources and Environmental Studies, University of Kordofan, Elobeid in Sudan, during March-June 2015 to assess the effect of six treatments on germination of cowpea seeds infested by Callosobruchus chinensis Linn., a serious Coleoptera pest which damages cowpea seeds. The agents used were groundnut oil, wood ash, sand, neem leaves powder, Rabal leaves powder and hot pepper powder. In the lab bioassay, the results obtained due to the infestation by C. chinensis showed that there were highly significant differences （P 〉 0.01） in the number of holes per 100 cowpea seeds between the different treatments at intervals of one month, and up to the end of the storage period, the numbers of holes per 100 cowpea seeds were 44, 740, 859, 856, 841 and 892 holes in the treatments, respectively. The germination of seeds treated with groundnut oil was 60%, while it was zero for the other treatments. It was concluded that the groundnut oil made creamy coat on the seeds and prevented the development of eowpea beetle infestation. Hence, it can be used by farmers at local levels to protect seeds for cultivation.

Allelopathy of Medicinal Plants: Current Status and Future Prospects in Weed Management

An attempt has been made in this article to accumulate and elucidate the literatures about the allelopathic potentiality of medicinal plants, and its role on the development of bio-herbicides for eco-friendly weed management strategies to conserve bio-diversity and ecological balance. This review paper has been prepared by comprehensive studies of various published research articles, books and proceedings available in the world literature. The farmers of different countries use several weed management techniques in order to minimize the deleterious effect of weeds. Among them most commonly used practice is application of herbicides due to its high efficacy and cost effectiveness, less time-consuming nature, flexibility and easy accessibility, and more rapid out return. Although use of synthetic herbicides in the crop fields has increased the crop production as well as the productivity by reducing the weed infestation, over time it causes a number of environmental hazards. Hence, to avoid these detrimental effects of synthetic herbicide, a lot of efforts have been dedicated by the researchers to search the novel natural plant products mainly allelochemicals and try to apply them as a tool for the development of bio-degradable natural herbicides. This paper intended to reflect the current state of allelopathic medicinal plants and their potentiality to develop eco-friendly and natural product-based herbicides for sustainable agriculture, and to invite further debate on this issue.

Antagonistic Potential of Bacterial Species against Fungal Plant Pathogens(FPP)and Their Role in Plant Growth Promotion(PGP):A Review

Since the 19th century to date,the fungal pathogens have been involved in causing devastating diseases in plants.All types of fungal pathogens have been observed in important agricultural crops that lead to significant pre and postharvest losses.The application of synthetic fungicide against the fungal plant pathogens(FPP)is a traditional management practice but at the same time these fungicides kill other beneficial microbes,insects,animal,and humans and are harmful to environment.The antagonistic microorganism such as bacteria are being used as an alternate strategy to control the FPP.These antagonistic species are cost-effective and eco-friendly in nature.These biocontrol bacteria have a broad mechanism against fungal pathogens present in the phyllosphere and rhizosphere of the plant.The antagonistic bacteria have different strategies against the FPP,by producing siderophore,biofilm,volatile organic compounds(VOCs),through parasitism,antibiosis,competition for limited resources and induce systemic resistance(ISR)in the host plant by activating the immune systems.The commercial bio-products synthesized by the major bacterial species Pseudomonas syringae,Burkholderia cepacia,Streptomyces griseoviridis,Pseudomonas fluorescens and Bacillus subtilis are used to control Fusarium,Pythium,Rhizoctonia,Penicillium,Alternaria,and Geotrichum.The commercial bio-formulations of bacteria act as both antifungal and plant growth regulators.The Plant growth-promoting rhizobacteria(PGPR)played a significant role in improving plant health by nitrogen-fixing,phosphorus solubilization,phytohormones production,minimizing soil metal contamination,and by ACC deaminase antifungal activities.Different articles are available on the specific antifungal activity of bacteria in plant diseases.Therefore,this review article has summarized the information on biocontrol activity of bacteria against the FPP and the role of PGPR in plant growth promotion.This review also provided a complete picture of scattered information regarding antifungal activities of bacteria and the role of PGPR.

Erratum to “Census Ethnobotanical Study of Some Plants Used in Traditional Medicine in the City of Meknes” [American Journal of Plant Sciences 5 (2014) 2480-2496]

An ethnobotanical survey was conducted in the city of Meknès over a period of two years, from 2009 to 2011 with 1000 people (615 women, 385 men). Through the questionnaire, schedules were established to collect information on the use of therapeutic medicinal plants by the local population. This research has focused primarily on the general population, herbalists and healers. The present investigation has enumerated 194 species distributed in 165 genera and 72 families. The most represented families are Lamiaceae (18%), the Aseraceae, (17%), the Apiaceae (14%) and the Fabaceae (10%). The results of the survey show that 54% of individuals use both herbal medicine and modern medicine, 26% of individuals use herbs and 20% use modern medicine. We are interested in the use of plants in different ages and sexes. We report that 31% of the population is aged between 51 and 60 years, 29% between 41 and 50 years, 23% between 31 and 40 years, 10% between 21 and 30 years, 3% less than 20 years and 4 % > 60 years. We note the predominance of women over men. Women use up to 61% against 39% of men. The analysis of our results shows that herbal medicine takes a place in the self-medication of the population studied. However, we emphasize an important point: Ignorance of toxic plants, in fact, only 19% of the target population recognizes these plants.

Gc-Ms Analysis and Antibacterial Activity of Mangosteen Leaf Extracts against Plant Pathogenic Bacteria

The potential of Garcinia mangostana as a biological control agent against plant pathogenic bacteria which decrease the quality and volume of crop production worldwide was assessed. Mangosteen leaves were extracted by maceration using chloroform, n-hexane, and methanol. For the in vitro antibacterial activity, two dissimilar species of plant pathogenic bacteria: Pseudomonas syringe pv. tomato and Xanthomonas oryzae pv. oryzae were acquired. Four different concentrations, 12.5, 25, 50, and 100 mg/ml were obtained through the cup-plate agar diffusion technique. Streptomycin sulphate at 30 μg/ml concentration was set as the positive control, whereas every respective solvent used in the leaf extraction was set as the negative control. The results have shown that, only methanol extract demonstrated antibacterial activity when tested on the plant pathogenic bacteria. The highest diameter of inhibition zones was observed in X. oryzae pv. oryzae, at all range of concentrations, followed by P. syringae pv. tomato. The least methanol extract concentration utilised in determination of minimum inhibitory concentration (MIC) assay was at 1.562 mg/ml, inhibiting X. oryzae pv. oryzae, followed by P. syringe pv. tomato at a concentration 3.125 mg/ml. Antibacterial impacts of the most effectual extract of mangosteen crude were supported by the existence of chemical components identified by GC-MS. Cycloartenol, Caryophyllene, Docosane, Phenol, 4,4-Methylenebis (2,6-di-tert-butylphenol) and Chromium were noted as key compounds in the mangosteen leaf extract, which were perhaps causing the antibacterial activity.

In vitro and in silico studies of salicylic acid on systemic induced resistance against bacterial leaf blight disease and enhancement of crop yield

Salicylic acid(SA)is an effective elicitor to promote plant defenses and growth.This study aimed to investigate rice(Oryza sativa L.)cv.Khao Dawk Mali 105 treated with salicylic acid(SA)-Ricemate as an enhanced plant protection mechanism against bacterial leaf blight(BLB)disease caused by Xanthomonas oryzae pv.oryzae(Xoo).Results indicated that the use of SA-Ricemate as a foliar spray at concentrations of more than 100 mg L^(-1)can reduce the severity of BLB disease by 71%.SA-Ricemate treatment also increased the hydrogen peroxide(H_(2)O_(2))content of rice leaf tissues over untreated samples by 39–61%.Malondialdehyde(MDA)in rice leaves treated with SA-Ricemate also showed an increase of 50–65%when comparing to non-treated samples.The differential development of these defense compounds was faster and distinct when the SA-Ricemate-treated rice was infected with Xoo,indicating plant-induced resistance.Besides,SA-Ricemate elicitor at a concentration of 50–250 mg L^(-1)was correlated with a substantial increase in the accumulation of total chlorophyll content at 2.53–2.73 mg g^(-1)of fresh weight which suggests that plant growth is activated by SA-Ricemate.The catalase-and aldehyde dehydrogenase-binding sites were searched for using the CASTp server,and the findings were compared to the template.Chemsketch was used to design and optimize SA,which was then docked to the catalase and aldehyde dehydrogenase-binding domains of the enzymes using the GOLD 3.0.1 Software.SA is shown in several docked conformations with the enzymes catalase and aldehyde dehydrogenase.All three catalase amino acids(GLN7,VAL27,and GLU38)were discovered to be involved in the creation of a strong hydrogen bond with SA when SA was present.In this mechanism,the aldehyde dehydrogenase amino acids LYS5,HIS6,and ASP2 were all implicated,and these amino acids created strong hydrogen bonds with SA.In field conditions,SA-Ricemate significantly reduced disease severity by 78%and the total grain yield was significantly increased which was an increase of plant height,tiller per hill,and panicle in three field trials during Aug–Nov 2017 and 2018.Therefore,SA-Ricemate can be used as an alternative elicitor on replacing harmful pesticides to control BLB disease with a high potential of increasing rice defenses,growth,and yield components.

群体饲养生命表:资料分析理论与转化为个体生命表的方法

本文介绍群体饲养生命表的资料分析基本原理及转换为个体生命表的方法。每日群体饲养生命表的记录实际上即年龄-龄期两性生命表的矩阵N,而每日所有雌虫的总繁殖力记录即为矩阵F_(total)。利用矩阵N与矩阵F_(total)可以计算年龄-龄期存活率矩阵S、繁殖力矩阵F及各种群参数。以桃蚜Myzus persicae和马铃薯块茎蛾Phthorimaea operculella为例,阐明群体饲养生命表分析的理论依据,证明群体饲养生命表得到的各项参数可靠,并介绍了一种将群体饲养生命表转化为个体生命表的方法。比较了群体饲养生命表和个体饲养生命表的特点。利用群体饲养研究昆虫生命表可以节省大量人力、时间与经费,群体饲养生命表可用于设计大量饲养生物防治天敌、鱼与鸟的饲料昆虫以及可供人类食用的昆虫。

Nano/Micro-Structural Supramolecular Biopolymers: Innovative Networks with the Boundless Potential in Sustainable Agriculture

Sustainable agriculture plays a crucial role in meeting the growing global demand for food while minimizing adverse environmental impacts from the overuse of synthetic pesticides and conventional fertilizers.In this context,renewable biopolymers being more sustainable offer a viable solution to improve agricultural sustainability and production.Nano/micro-structural supramolecular biopolymers are among these innovative biopolymers that are much sought after for their unique features.These biomaterials have complex hierarchical structures,great stability,adjustable mechanical strength,stimuli-responsiveness,and self-healing attributes.Functional molecules may be added to their flexible structure,for enabling novel agricultural uses.This overview scrutinizes how nano/micro-structural supramolecular biopolymers may radically alter farming practices and solve lingering problems in agricultural sector namely improve agricultural production,soil health,and resource efficiency.Controlled bioactive ingredient released from biopolymers allows the tailored administration of agrochemicals,bioactive agents,and biostimulators as they enhance nutrient absorption,moisture retention,and root growth.Nano/micro-structural supramolecular biopolymers may protect crops by appending antimicrobials and biosensing entities while their eco-friendliness supports sustainable agriculture.Despite their potential,further studies are warranted to understand and optimize their usage in agricultural domain.This effort seeks to bridge the knowledge gap by investigating their applications,challenges,and future prospects in the agricultural sector.Through experimental investigations and theoretical modeling,this overview aims to provide valuable insights into the practical implementation and optimization of supramolecular biopolymers in sustainable agriculture,ultimately contributing to the development of innovative and eco-friendly solutions to enhance agricultural productivity while minimizing environmental impact.

Decoding the fruit microbiome:A climate smart strategy to manage postharvest decays

There is an urgent necessity to shift our diets toward those rich in fruits and vegetables and at reduce postharvest losses of perishables.Approximately 20%-50%of fruits and vegetables are lost due to poor postharvest handling and pathogen infections in developing countries while it was estimated as 5%-35%in developed countries. Fresh fruits have evolved with a plethora of microorganisms having important roles in maintaining fruit health. However, little information is available on the dynamics, structure, and functional capacities of underpinning fruit microbiomes. The present review discussed environmental conditions favoring fruit-harbored antagonists and their different modes of action for suppressing postharvest pathogens in fruits. It also provides information on omics technologies such as next-generation sequencing (NGS),metaproteomics, metatranscriptomic, and metabolomics studies to characterize fruit microbiomes. With the advent of NGS and meta-omics technologies, microbiome research could bring remarkable development and understanding in succeeding biological treatments. In addition, they may provide us with a fundamental understanding of microclimate requirements for fruit microbiome establishment and microbiome shifts during post-harvest storage, which would be advantageous in developing composite biocontrol treatments for post-harvest decay management.

Degradation of chlorpyrifos alone and in combination with chlorothalonil and their effects on soil microbial populations

In practice, pesticides are usually applied simultaneously or one after another for crop protection, and this type of pesticide application often leads to a combined contamination of pesticide residues in the soil environment. A laboratory study was conducted to investigate the influence of chlorothalonil on chlorpyrifos degradation and its effects on soil bacterial, fungal, and actinomycete populations. Under the experimental conditions here, the half-lives of chlorpyrifos alone, and in combination with chlorothalonil, at the recommended and double dosages, were measured to be 3.24, 2.77, and 2.63 d, respectively. Chlorpyrifos degradation was not significantly altered by its combination with chlorothalonil. However, the inhibitory effect of chlorpyrifos on soil microorganisms was increased by its combination with chlorothalonil, and the increase was related to the levels of chlorothalonil added. Compared to those in the controls, the populations of bacteria, fungi, and actinomycetes were significantly reduced by 44.1%, 61.1%, and 72.8%, respectively, on the first day after treatment （DAT） by chlorpyrifos alone. With the addition of chlorothalonil, the inhibition was increased to 55.2%, 79.3%, and 85,8% at the recommended dosage, and 86.0%, 94.1%, and 90.8% at the double dosage, at one DAT, respectively. The results suggested that combined effects should be taken into account to assess the actual impacts of pesticide applications.

Degradation of chlorpyrifos in laboratory soil and its impact on soil microbial functional diversity

Degradation of chlorpyrifos at different concentrations in soil and its impact on soil microbial functional diversity were investigated under laboratory condition. The degradation half-live of chlorpyrifos at levels of 4, 8, and 12 mg/kg in soil were calculated to be 14.3, 16.7, and 18.0 d, respectively. The Biolog study showed that the average well color development （AWCD） in soils was significantly （P 〈 0.05） inhibited by chlorpyrifos within the first two weeks and thereafter recovered to a similar level as the control. A similar variation in the diversity indices （Simpson index lID and McIntosh index U） was observed, but no significant difference among the values of the Shannon-Wiener index H＇ was found in chlorpyrifos-treated soils. With an increasing chlorpyrifos concentration, the half-life of chlorpyrifos was significantly （P ≤ 0.05） extended and its inhibitory effect on soil microorganisms was aggravated. It is concluded that chlorpyrifos residues in soil had a temporary or short-term inhibitory effect on soil microbial functional diversity.

Studies on the management of root-knot nematode, Meloidogyne incognita-wilt fungus, Fusarium oxysporum disease complex of green gram, Vigna radiata cv ML-1108

Studies were conducted under pot conditions to determine the comparative efficacy ofcarbofuran at 1 mg a.i./kg soil, bavistin at 1 mg a.i./kg soil, neem （Azadirachta indica） seed powder at 50 mg/kg soil, green mould （Trichoderma harzianum） at 50.0 ml/kg soil, rhizobacteria （Pseudomonas fluorescens） at 50.0 ml/kg soil against root-knot nematode, Meloidogyne incognita-wilt fungus, Fusarium oxysporum disease complex on green gram, Vigna radiata cv ML-1108. All the treatments significantly improved the growth of the plants as compared carbofuran and A. indica seed powder increased plant growth to untreated inoculated plants. Analysis of data showed that and yield significantly more in comparison to bavistin and P. fluorescens. Carbofuran was highly effective against nematode, bavistin against fungus, A. indica seed powder against both the pathogens and both the bioagents were moderately effective against both the pathogens.