Bioefficacy of Iprodione Against Two Desapers,its Compatibility with T. harzianum and Residues on Cabbage Crop

Iprodione (3-(3,5-dichlorophenyl)-N-isopropyl-2,4-dioxoimidazolidine-1-carboxamide) bio-assayed against fungi Alternaria brassicicola and Sclerotinia sclerotiorum was found to be highly effective for inhibiting these desapers. Inhibition of A. brassicicola was 100% up to the dose of 75 ppm and for S. sclerotiorum there was 50% inhibition for the same concentration. Formulation of the pesticide was applied @ 500 and 1000 g. a.i./ha on the cabbage crop grown in the fields. Residues in the edible sample of cabbage were analyzed by gas choromatography for the fungicide and its metabolites. The dissipation of residues of the fungicide and its bio-efficacy against two fungi are presented. It dissipated from 3.72 to 0.072 μg/g on cabbage head by 15 days after treatment. The EC₅₀ values of iprodione were found to be 11.5 ppm and 79.4 ppm for A. brassicicola and S. sclerotiorum, respectively. Half-life of iprodione was found to be 3 days for both cabbage head and leaves. The compatibility of the fungicide with a bio agent, T. harzianum was also studied and these two were not found to be compatible.     

Inhibition of Alternaria stem canker on tomato by essential oils from Baccharis species

Abstract

The toxicity of four essential oils extracted from Baccharis articulata, Baccharis ochracea, Baccharis psiadioides and Baccharis trimera was tested against the phytopathogen Alternaria alternata, which causes Alternaria stem canker on tomatoes. Diseases caused by Alternaria fungi are responsible for great economic losses in terms of production and are controlled by synthetic fungicides; however, essential oils offer an alternative, since they have been proven to be effective for controlling against various plant pathogens. In this way, the antifungal activity of Baccharis essential oils was tested using potato dextrose agar medium with concentrations ranging from 0.1 to 20.0?µL mL^?1. Baccharis trimera and Baccharis ochracea essential oils presented 100% mycelial growth inhibition of A. alternata and were also able to control Alternaria stem canker disease under greenhouse conditions. Tomato plants treated with these essential oils exhibited area under the disease progress curve (AUDPC) values of 230.10 and 241.42, differing from the control condition, which showed an AUDPC value of 268.92. The essential oils of B. trimera and B. ochracea can be an alternative for controlling Alternaria stem canker disease of tomatoes and should be formulated as a potential fungicide against the A. alternata pathogen.     

枯草芽孢杆菌H110对苹果梨采后青霉病和黑斑病的抑制效果

将具有广谱拮抗作用的枯草芽孢杆菌(Bacillus subtilis)H110作为生防菌株,研究了该菌的培养液、滤液、菌悬液及蛋白粗提液对苹果梨(Pyrus bretschneideri Rehd.)青霉病(Penicillium expansum Link)和黑斑病(Alternaria alternate)的抑制效果.H110的蛋白粗提液的抑制作用最好,青霉病和黑斑病的发病率分别比对照低92.7%和86.6%,病斑直径也显著小于对照;其次为菌培养液和菌悬液,滤液的抑制效果相对较差,但4种处理均显著好于对照.4种处理对病原菌孢子萌发的抑制效果与in vivo试验的效果一致.实验结果表明,枯草芽孢杆菌通过产生抗菌蛋白和竞争作用抑制病原菌生长.图1表2参17     

链格孢菌对白车轴草抗旱性的影响

在盆栽自然水分干旱胁迫条件下,研究了接种链格孢菌(Alternaria tenuis Nees)对白车轴草(Trifolium repens L.)抗旱性相关的生理生化指标的影响,结果表明:接种组与对照组叶片的电导率(EC)、丙二醛(MDA)含量、脯氨酸(Pro)含量均与干旱处理时间呈显著正相关,而叶片相对含水量(RWC)、抗坏血酸(ASA)含量与处理时间呈显著负相关。链格孢菌的侵染能促进干旱胁迫下白车轴草叶片EC和MDA含量的增加,延缓Pro的积累,加速叶片RWC和ASA含量的降低。到达干旱处理的第6天,接种组的EC、MDA含量分别比对照高20.06%、68.79%(p<0.05),而RWC、Pro含量和ASA含量分别比对照低7.03%、25.3%、77.43%(p<0.05)。此外,接种组超氧化物歧化酶(SOD)、过氧化物酶(POD)活性均于处理的第4天开始显著低于对照;过氧化氢酶(CAT)活性也于处理的第6天下降并显著低于对照,为对照的79.79%(p<0.01)。表明链格孢菌会降低干旱胁迫下白车轴草的渗透调节能力和保护酶的活性,加剧活性氧的积累和膜脂过氧化程度,使白车轴草的抗旱性降低。     

Eco-friendly PEG-based controlled release nano-formulations of Mancozeb: Synthesis and bioefficacy evaluation against phytopathogenic fungi Alternaria solani and Sclerotium rolfsii

Controlled release (CR) nano-formulations of Mancozeb (manganese-zinc double salt of N,N-bisdithiocarbamic acid), a protective fungicide, have been prepared using laboratory-synthesized poly(ethylene glycols) (PEGs)-based functionalized amphiphilic copolymers without using any surfactants or external additives. The release kinetics of the developed Mancozeb CR formulations were studied and compared with that of commercially available 42% suspension concentrate and 75% wettable powder. Maximum amount of Mancozeb was released on 42nd day for PEG-600 and octyl chain, PEG-1000 and octyl chain, and PEG-600 and hexadecyl chain, on 35th day for PEG-1000 and hexadecyl chain, on 28th day for PEG-1500 and octyl chain, PEG-2000 and octyl chain, PEG-1500 and hexadecyl chain, and PEG-2000 and hexadecyl chain in comparison to both commercial formulations (15th day). The diffusion exponent (n value) of Mancozeb in water ranged from 0.42 to 0.62 in tested formulations. The half-release (t_1/2) values ranged from 17.35 to 35.14 days, and the period of optimum availability of Mancozeb ranged from 18.54 to 35.42 days. Further, the in vitro bioefficacy evaluation of developed formulations was done against plant pathogenic fungi Alternaria solani and Sclerotium rolfsii by poison food technique. Effective dose for 50% inhibition in mgL^?1 (ED₅₀) values of developed formulations varied from 1.31 to 2.79 mg L^?1 for A. solani, and 1.60 to 3.14 mg L^?1 for S. rolfsii. The present methodology is simple, economical, and eco-friendly for the development of environment-friendly CR formulations of Mancozeb. These formulations can be used to optimize the release of Mancozeb to achieve disease control for the desired period depending upon the matrix of the polymer used. Importantly, the maximum amount of active ingredient remains available for a reasonable period after application. In addition, the developed CR formulations were found to be suitable for fungicidal applications, allowing use of Mancozeb in lower doses.     

多主枝孢粗毒素提取及抑菌活性研究

采用生长速率法和孢子萌发法研究多主枝孢毒素粗提物TIC和TOC对小麦赤霉病菌、番茄早疫病菌菌丝生长和孢子萌发的抑制作用.结果表明,TIC和TOC对两种供试病菌菌丝生长和孢子萌发都有一定的抑制作用,且对菌丝生长抑制作用的强度与毒素浓度呈正相关.TOC对番茄早疫病菌菌丝生长的抑制作用强于对小麦赤霉病菌的抑制作用,而TIC在较高浓度下对番茄早疫病菌菌丝生长的抑制作用较强.TIC和TOC对番茄早疫病菌孢子萌发的抑制作用均强于小麦赤霉病菌.     

链格孢菌菌株致病性及其遗传差异性

对分离自紫茎泽兰的19个链格孢菌菌株的致病性进行了比较研究，并对这19个菌株和其它来源的3个菌株的5．8S rDNA及其两侧的ITS1区和ITS2区进行了序列分析．结果显示，链格孢菌菌株的致病性差异明显；21株链格孢菌菌株在5．8SrDNA及其两侧的转录问区（ITS区）的序列无差异，而与百日草链格孢菌（Alternaria zinnine）的序列差异显著，表明21株链格孢菌菌株属种内变异．采用AFLP分子标记技术对21株链格孢菌的DNA扩增片段长度多态性进行了分析，结果表明，链格孢菌自然变异群体内存在很高的遗传多样性．链格孢菌菌株的相似性与菌株的地理来源有一定的相关性，但基于AFLP标记划分的AFLP类群与基于寄主病情指数划分的致病力类群问关系不相一致；起始菌株与变异菌株相似性显著，但二者和致病性的关系不显著．图2表1参18