Efficacy of plant oils against grain discolouration of rice under in vitro condition

Grain discolouration is an important constraint in reducing productivity of rice. Curvularia lunata and Exserohilum rostratum are two important pathogens responsible for it. An in vitro study was undertaken to test the efficacy of different plant oils against these pathogens. It revealed from the experiment using poison food technique that all the plant oils recorded a significant inhibition over control. Among the different concentration (1, 2 and 3%) of plant oils such as Eucalyptus, Neem Pungam, Coconut and Mahua oil were tested. The result revealed that eucalyptus oil (3%) recorded the complete mycelial inhibition of C. lunata (100 %) and E. rostratum (78%) followed by pungam oil (58.8 % of C. lunata), (52% of E. rostratum) and least mycelial growth were recorded by coconut oil (3%). Our findings suggest that the plant oils may be valuable as potential antifungal properties against grain discolouration of rice.

Bio-Control Efficiency of Trichoderma viride against Stem Rot of Tuberose Caused by Sclerotium rolfsii

Tuberose is an important flower crop for cut flower and decorations which is a chief raw material for the production of high-grade perfumes. Recent days stem rot of tuberos is an important disease that affects the quality of flowers. The objective of this paper is to evaluate the efficiency of T. viride isolates against S. rolfsii and improves growth parameters of tuberose. Among the different antagonists tested, Trichoderma is found be very effective against S. rolfsii. The isolates T. viride are named as Tv1 – Tv10. The efficient isolate have been identified as Tv5 by dual culture technique, which shows maximum mycelial inhibition (77.15), this was followed by the isolates Tv4 (75.94) and Tv1 (72.96) in the decreasing order, the least growth inhibition of pathogen was exhibited by the isolate Tv10 (55.72 %). The poison food technique @ 40 % concentration completely inhibits the mycelial growth on solid media.

Antifungal activity of crude extracts of Ageratum conyzoides and Chromolaena odorata for management of Lasiodiplodia theobromae and Lasiodiplodia pseudotheobromae through in vitro evaluation

Lasiodiplodia is an important genus of fungi causing destructive diseases on perennial crops, including cocoa. Two crucial species of Lasiodiplodia that cause diseases in cocoa are Lasiodiplodia theobromae and Lasiodiplodia pseutheobromae. A variety of weeds is the potential to be applied as botanical fungicides to control the pathogens. The main objective of this study was to evaluate Ageratum conyzoides and Chromolaena odorata leaf extract to inhibit the growth of L. theobromae and L. pseudotheobromae on a synthetic medium. Solvent organic was methanol for weed extraction with a ratio of 1:5. The experiment was conducted through the poison food technique method, both in the solid and liquid medium in three different concentrations, 1, 3, and 5%. The result showed that A. conyzoides and C. odorata were significantly inhibited the colony growth of both Lasiodiplodia in all concentrations in a solid medium. A. conyzoides performed better than C. odorata in all concentrations of both Lasiodiplodia in inhibition. A. conyzoides 5% performed well to suppress the colony growth of L. pseudotheobromae (100%), followed by A. conyzoides 3% and A. conyzoides 1%. A. conyzoides 5% able to inhibit the colony growth of L. theobromae until 100%, followed by A. conyzoides 3% and 1%. Meanwhile, A. conyzoides and C. odorata extract tested on PDB medium at 1, 3, and 5% reduced the fungal biomass significantly at all concentrations. C. odorata was found most effective in inhibiting fungal biomass of both pathogens either on wet weight or on dry weight at 1, 3, and 5% %. A. conyzoides and C. odorata can manage the growth of L. theobromae and L. pseudotheobromae through in vitro conditions.

Bio-safety assessment of nanozeolites of varying size and doses on soil beneficial microorganisms

Aim: To evaluate the toxic effects of nano-zeolites on soil beneficial microorganisms. Methodology: This study involved dry milling of zeolites at varying parameters to obtain dry-milled zeolites of four size regimes such as 10-100 nm, 200-400 nm, 500-1000 nm and 1000-2000 nm that were tested at incremental concentrations such as 100 ppm, 1000 ppm and 2000 ppm along with control on various soil beneficial microorganisms. Three replications were done for each treatment with factorial completely randomized design. The poison food technique, growth curve assessment followed by cytotoxicity and genotoxicity studies on all four bacterial genera treated with zeolites of varying sizes and doses were undertaken. The effects of zeolite on average linear growth rate (ALGR) of biocontrol agent, Trichoderma viride were also studied. Results: The effect of zeolites tested on four bacterial genera viz. Azotobacter chroococcum, Rhizobium leguminosarum, Bacillus megaterium and Pseudomonas fluorescens using poison food technique and growth curve revealed that zeolites regardless of size or concentration had positively influenced the growth dynamics of all four bacteria tested. The effect of zeolite on average linear growth rate (ALGR) of Trichoderma viride also indicated that incremental dose of zeolite had a positive effect. Lactose dehydrogenase revealed that 2000 ppm nano-zeolite exhibited cytotoxic effects on soil beneficial micro-organisms tested. On the other hand, comet assay demonstrated no quantifiable DNA damage in nano-zeolite treated cells in comparison to control cultures. Interpretation: This study unequivocally demonstrated that zeolites of size greater than 200-400 nm, irrespective of doses even up to 2000 ppm are quite safe for soil beneficial microbes.

Bioefficacy of fungicides and bioagents against Macrophomina phaseolina causing charcoal rot in maize

In recent years Macrophomina phaseolina causing charcoal rot of maize is more problematic in maize growing parts of Maharashtra. Present investigation was taken on evaluation of fungicides and bio-agents against M. phaseolina under laboratory condition and pot culture. Under laboratory condition, nine fungicides and six bio- agents were evaluated against M. phaseolina by poison food technique and dual culture method, respectively. Among fungicides Carbendazim 63 % + Mancozeb 12% and Carbendazim alone recorded maximum inhibition of (100 %) mycelial growth. Among the bio-agents tested Trichoderma harzianum was found more effective as compared to other bio-control agents and inhibited maximum fungal growth (63.33 %) of M. phaseolina. Under pot culture study, as soil application and seed treatment, among the fungicides, carbendazim + Mancozeb was found most effective. However, among bioagents Trichoderma harzianum was remarkably manage the charcoal rot.

IN- VITRO ASSAY OF ANTIFUNGAL ACTIVITY OF VARIOUS ELICITORS AND BINDERS AGAINST ALTERNARIA ALTERNATA

In the present study, in-vitro antifungal activity of various elicitors and binders were evaluated against Alternaria alternata, causative agent of early blight disease in Tomato. Antifungal activities were assayed by poison food technique. Among all elicitors and binders best optimum activity was observed for castor oil cake and cow dung 63.06% and 60 .95% respectively against Alternaria alternata. On the basis of results obtained, best active elicitor i.e., castor oil cake and binder cow dung can be used to develop the plant extract-based bio-formulation for effective control of leaf blight disease of Tomato in an eco-friendly manner.

In-vitro evaluation of botanicals and fungicides against Bipolaris sorokiniana, causing spot blotch of wheat

Spot blotch disease of wheat caused by Bipolaris sorokiniana; is one of the most concerning disease in warm and humid regions of Nepal due to its widespread prevalence and increasing severity. An in-vitro experiment was conducted to evaluate the efficacy of different botanicals and fungicides against Bipolaris sorokiniana, in National Plant Pathology Research Centre’s laboratory at Khumaltar, Lalitpur in 2019. The experiment was done in completely randomized design with three replications by poison food technique. Five botanicals viz. neem, garlic, eucalyptus, bojho and asuro at three different concentrations (5%, 10% and 15%) and eight fungicides viz. sectin, curex, bavistin, vacomil plus, saaf, sajha, criptan and tilt at three concentration levels (25 ppm, 50 ppm and 100 ppm) except curex (50 ppm, 100 ppm and 200 ppm) were used to evaluate the effect on the radial mycelial growth and mycelial growth inhibition percentage of the pathogen. The different botanical extracts and fungicides in different concentrations inhibited the mycelial growth of fungus significantly (p<0.01). The highest mycelial growth inhibition percentage was found by the application of garlic clove extract (52.85%) at 15% which was followed by bojho (52.48%) at 15% concentration. While tilt was found effective fungicide which completely inhibits the mycelial growth at all concentrations. Also, fungicides viz. sajha (79.78%), saaf (73.59%) and sectin (70%), at 100 ppm were found effective in controlling the pathogen as compare to others. Mycelial growth inhibition of the fungus was found to be increased with the increase in concentrations of botanicals and fungicides.

In-vitro evaluation of six bio-product against coriander stem gall disease

Stem gall of coriander caused by Protomyces macrosporus Unger. is a highly devastating seed and soil borne pathogen in coriander and has emerged as one of the major disease causing substantial quantitative and qualitative losses. In the present studies, efficacy of six bio-products, namely, Neemazal, cow urine, butter milk, fresh milk, beejamrit and jeevamrit was screened against mycelial growth inhibition of P. macrosporus under in vitro conditions. Extracts of these bio-products were evaluated at three different concentrations (i.e 10, 20 and 30%) by poison food technique. Results revealed that that among the various bio-products evaluated against test pathogen, irrespective of concentration tested, all the bio-products resulted in significant inhibition in mycelial growth of test pathogen with neemazal giving the complete inhibition [100.00 % (90.00)] followed by fresh milk [30.66 % (28.44)] and butter milk [26.55 % (25.99)], though these treatments were statistically different from one another. Different concentrations (10 to 30 %) of bio-products, irrespective of the treatments showed that 30 per cent concentration of all bio-products was most efficacious in inhibiting the mycelial growth of the test pathogen giving 69.95 per cent (36.77) growth inhibition. This was followed 20 and 10 per cent concentration of bio-products resulting in 55.58 per cent (32.49) and 45.53 per cent (16.30) growth inhibition, respectively. The result regarding evaluation of bio-products under in vitro conditions against the P. macrosporus showed that Neemazal treatment was most effective at all concentrations and completely inhibited the test fungus followed by 30 per cent fresh milk resulting in the mycelial growth inhibition of 51.60 per cent.

Synthesis and Evaluation of Isatin Derivatives as Antifungal Agents

Various types of isatin derivatives were synthesized by reacting isatin with different reagents viz substituted acetophenones, sodium nitrate, hydroxylamine hydrochloride and hydrazine hydrate. Characterization of the synthesized compounds was done by using various spectral techniques such as IR, 1HNMR, 13CNMR, elemental analysis and mass spectrometry. Synthesized compounds were further evaluated for their antifungal activity against Helminthosporium oryzae, Rhizoctonia solani and Fusarium moniliforme using poison food technique. 3-(2-Oxo-2-phenylethylidene) indolin- 2-one showed significant mycelium inhibition against all tested rice fungi.

In-Vitro Antagonistic Activity of Plant Extract on Fusarium Species

Plant protection is an important area which needs attention since most of the hazardous inputs added into the agricultural system are in the form of plant protection chemicals. Botanicals possess a variety of promising properties which make it a better biocontrol agent. The objectives of the present study were to isolate Fusarium sp. from soil and to check the effect of botanicals against this fungal pathogen in-vitro. The antagonistic activity of botanicals was studied by co-inoculation with the Fusarium sp. isolated from rhizosphere soil. In poison food technique, the botanicals in different concentration, showed decrease in the growth of the fungal pathogen. Maximum inhibition was observed in 10% Azadiracta sp. with 64% inhibition followed by 5% Azadiracta sp. with 57.8%