Experiments were carried out to study the effect of six selected plant extracts viz., Calotropis procera, Azadirachta indica leaf and seed kernel, Allium sativum bulb, Withania somnifera leaf and Solanum suratteuse green berry on mycelial growth and spore germination of Alternaria brassicae in vitro. Influence of these extracts used as foliar sprays on host defense related biochemical parameters i.e. soluble phenol, sugar and protein content, peroxidase, polyphenol oxidase and phenylalanine ammonia lyase activities in mustard leaves was observed. The effect of plant extracts on intensity of Alternaria blight and seed yield in mustard was also recorded. The results revealed that all the six plant extracts Calotropis procera, Azadirachta indica leaf extract, A. indica seed kernel, Allium sativum bulb, Withania somnifera leaf and Solanum suratteuse green berry prepared in distilled water, acetone or methanol, significantly inhibited the mycelial growth and spore germination of A. brassicae at 5, 10 and 15 per cent concentrations in potato dextrose agar medium. The aqueous extract of A. indica seed kernel was most inhibitory to mycelial growth and spore germination of A. brassicae.
Amongst various factors responsible for lowering down the yield of rapeseed-mustard, blight caused by Alternaria brassicae (Berk) Sacc. and Alternaria brassicicola (Schw.) Wiltshire is of greate importance. Blight symptoms appear as dark brown lesions with concentric rings in centre on leaves. Lesions on stem and pods are elongated and infected pods produce small, discoloured and shriveled seeds. Genotypes and fungicides play an important role in management of this disease. Plant extracts tested in present study inhibeted the fungal mycelial growth in between 48.90 to 77.80% at 10% concentration in invitro. In field condition disease was managed with the fungicides quntal @ 0.2%, a mixture of iprodione (25%) and carbendazim (25%) effectively.
Fungicides mancozeb and carbendazim caused 100% reduction in mycelial growth of Alternaria brassicae over control in vitro while 1% (w/v) aqueous bulb extract of Allium sativum and leaf extract of Acacia nilotica caused significant reductions. In dual culture, GR isolate of Trichoderma viride performed the best among the test isolates of Trichoderma, causing 81%, 82% reduction in mycelial growth of A. brassicae over control. Performance of isolates SI-2, P and SI-1 of T. viride were at par (P > 0.01) with that of GR isolate. Spraying of A. brassicae at different ages of the mustard host plant identified 75 days after sowing (d.a.s.) as the most critical age of the mustard plant for development of Alternaria blight severity on the crop with 45 d.a.s. being the next most important one. Mancozeb was the best among all the treatments, resulting in the lowest disease severity on leaves of mustard at both Sewar and Ludhavai as also the lowest A-value (area under disease progress curve). Performance of bulb extract of A. sativum in checking the disease severity on leaves and pods was at par (P > 0.05) with mancozeb. The GR isolate of T. viride was at par with mancozeb in checking blight s
Antifungal activity of Chromolaena odorata aqueous extract against Alternaria blight (Alternaria brassicae) was examined in vitro and in planta. In vitro, the extract was able to inhibit conidial germination and mycelial growth whereas, in planta, foliar treatment with C. odorata extract reduced disease incidence and severity in Brassica oleracea. Besides the extract, Candida sp. was also tested for its antifungal activity against A. brassicae and it was also efficient against conidial germination and mycelial growth, whereas in planta, no effect was observed on disease incidence and severity. C. odorata extract and Candida sp. had no effect on B. napus seed germination and induction of ?-1,3-glucanase activity.
Biological control is an approach that provides safe fungal management program, and corresponds to a substitute for reliance on chemical treatment methods. It is often used to gradually suppress widespread infestations in low value or remote areas where other methods are not feasible. Natural plants derived compounds contribute a lot in fight against pathogens.Numerous studies conducted in Pakistan revealed a wide spectrum prospects of using extracts of plants for biological control of pathogenic fungi. On the basis of efficacy of plant extracts, present study has been designed to find out the effective plant product to control Alternaria alternata in vitro by using medicinal plant, Tagetus errectus, and molecular characterization of Alternaria alternata.
The study demonstrate morphological and physiological variations in isolates of Alternaria brassicae and to evaluate the efficacy of fungicide (in vitro) on radial growth of the fungus and foliar sprays (field) against the disease severity on rapeseed-mustard. Morphological variations of A. brassicae obtained from various places were differed in their conidial size and septation. Physiological response of A. brassicae at varying temperatures, the fungus showed its maximum growth at 25°C followed 20°C and on different culture medium, maximum radial growth is on PDA. However, the fungus exhibited a descending trend in its growth at lower and higher regimes of temperature. Among the non systemic and systemic fungicides evaluated in vitro on radial growth inhibition of A. brassicae were found significantly most effective and reduced maximum radial growth at higher concentration. All fungicidal sprays applied under field conditions to manage the incidence of blight reduced significantly the severity of the disease and increased yield in comparison to untreated control. Ridomil-MZ proved to be most effective. Highest net profit as well as cost : benefit ratio was Bavistin + Indofil-Z 78.
Indian mustard (Brassica juncea) commonly grown in rabi season (October-November), contribute 28.60% in total production of oilseed. The crop is prone to various diseases, amongst them Alternaria brassicae causing blight is more devastating in decreasing the production. It also affects of quality of seed by reducing its size, colour and oil content. Pathogen survives in infected plant debris throughout year stored at room temperature and refrigerated condition. Extract of Syperus rotundus and piper nigrum most effective in reducing the mycelia growth of fungus. Since use of fungicides, provide resistance against pathogens and pollute the environment, the efforts were made to identify the resistance inducing chemicals. For this, Isonicotinic acid and NAA @ 0.1% was found most effective in managing the disease.
Rapeseed-mustard is one of the most important oilseed crop, grown both in tropical and subtropical regions of the world. It is plays a pivotal role in agricultural economy of the world. The oil of rapeseed-mustard serves as a very good cooking medium and dietary fat of the majority of populations. It is also most common medium of pickling and food preserving. Besides oil, the leaves of young plants are used as green vegetables and whole plant as green fodder. The seeds are highly nutritive containing 37.7-52.9% euric acid, 8.5-19.0% linoleic acid and 8.6-17.1% oleic acid. These crops are affected by several foliar diseases. Among them Downey mildew [Peronospora brassicae (Pers. ex. Fr.) Fr.], Alternaria blight [Alternaria brassicae (Berk) Sacc. and Alternaria brassicicola (Schwein) Wiltshire] and white rust [Albugo candida (Pers. ex Lev.) Kuntze] are most important in reducing the seed yield. These diseases also affect the seed size, seed quality and oil content.
Analysis of morphological and cultural variability among thirteen isolates of Alternaria brassicae provides information about morphological variation and favorable cultural conditions in vitro when such situations become available under cropping environment, which could result in severe infection of Alternaria blight due to isolates existing in different geographical regions of India. This also reflected the adaptation of the respective isolates to the ambient conditions in the different cropping areas, where the disease occurs in varied proportions in different years, which may have also induced the available cultural variability. This work discusses the possible disease scenario in view of global warming and climate change. Although genetic variability could be found by RAPD, no genetic variability could be located among A. brassicae isolates by ITS-AFLP. So, variability did exist at genomic level but not in the highly conserved region of the genome and pathogenic variability also existed among isolates of A. brassicae from different parts of India where oilseed Brassicas are grown and this information may help in easier development of Alternaria blight resistant Brassica.
This book describies the effect of plants extracts and essential oils against Red flour Beetle during the year 2010 at stored grain laborarty in Agricultural Entomology Department. The objective of study was to evaluate the the insecticidal activity of the plant extracts and essentional oils against Tribolium castaneum (Red Flour Beetle)under the laboratory conditions and to observe (1) Adult and Larval mortality (2)Population build up(3) Developmental inhibitation(4)Repellent effect of essential oils and plants extracts.The conclusion were withdrawn from the obtained results were showed that (1)Maximum mortality of grubs by the Citrus reticulata oil(2)In repellency test all the oils and extracts show significant results(3)In population builds up Citrus sinensis show better results(4)In developmental inhibitation all the oils and plant extracts show significant result against Tribolium castaneum.
Back to Nature at the 21 century. This books describes the medicinal importance of Rosemary, its tissue culture,phytochemical composition the antimicrobial activity of intact and callus extracts of this important medicinal plant. It contains a practical experiments regarding the inhibitory effects of extracts on pathogens infect skin. How rapidly extracts can heal induced injuries compared with skin ointments available in chemists. All these aspects and others are discussed and illustrated with photographs.
Efforts were made to assess the allelopathic effect of different concentrations (1, 3 and 5%) of leaf extracts of J. curcas on germination and seedling growth of wheat, mustard, til and black gram under bioassay conditions. Three accessions of J.curcas (NRCJ-7, NRCJ-18 and NRCJ-89) were selected for this phytotoxic experiment. The inhibitory effects of the J.curcas extracts on all the test crops were found. The toxicity of the Jatropha accessions was in the order (irrespective of concentrations) NRCJ-18 > NRCJ-7 > NRCJ-89 for wheat; NRCJ-89 > NRCJ-18 > NRCJ-7 for mustard; NRCJ-7 > NRCJ-89 > NRCJ-18 for til; NRCJ-7 > NRCJ-18 > NRCJ-89 for blackgram. From the holistic point of view wheat and til are least affected by Jatropha curcas than mustard and blackgram.
Research study on corrosion inhibitive action of plant Cordia Dichotoma revealed that the extracts of this plant effectively reduce the corrosion of mild steel and aluminium in acidic medium. Hence the extracts of Cordia Dichotoma may be used as safe, non toxic ecofriendly corrosion inhibitor. These extracts form a inhibitive protective layer on the metal surfaces and hence prevent them from corrosion.
In recent years, concerns have been raised about the environmental impact and the potential health risk related to the use of chemical fungicides in agriculture. Interests have been generated in the development of safer antifungal agents such as plant based essential oils and extracts. In the present study, crude methanol extracts from leaves of twelve different medicinal plant species were evaluated in vitro for their efficacy against phytopathogenic fungus Sclerotinia sclerotiorum that causes white mould disease in a wide a variety of crops. Further, five selected plant extracts were evaluated for management of white mould disease of french bean in field conditions. Application of extracts by seed treatment method was found to be more effective than soil and root dip treatments. Piper betle, Polygonum hydropiper and Vitex negundo extracts as seed treatment showed the best control effect in terms of reducing the infections and enhancing plant growth. These results provide promising baseline information on the potentiality of these plants to develop novel, efficient and eco friendly herbal antifungal products as alternatives of chemical fungicides.
The goal of this study was to screen different extracts of medicinal plants for their phenolics profile and antioxidant activities. Antiradical properties of the plant extracts were compared using stable DPPH•. Generally, ethanolic extracts had the strongest antiradical activities followed by ethyl acetate and finally hexane extracts. The ethanolic extracts of different plants were also markedly effective in inhibiting the oxidation of linoleic acid and the subsequent bleaching of ?-carotene in comparison with the control. The content of phenolic compounds (mg/g) in different extracts expressed in gallic acid equivalents (GAE), varied between 1.2 and 15.3. In all plant samples ethanolic extracts contained the highest levels of total phenolics and total flavonoids followed by ethyl acetate extracts and finally hexane extracts. The results are important for using those plants in different food and pharmaceutical applications.