Isolation and identification of bacterial strains from different tea growing areas against Macrophoma sp. in southern India tea plantation

Branch canker is an important secondary stem disease in tea caused by Macrophoma theicola. Three different Macrophoma spp. were identified from three tea growing regions of southern India and their identity was confirmed by 18S rRNA method. Bacterial biocontrol isolated from four different locations of south India were also identified through 16S rRNA method. The bacterial strains were identified and evaluated for their antagonistic potential for the control of branch canker. Dual plate technique revealed that among the four bacterial strains, Bacillus amyloliquefaciens (78.9±0.4) showed maximum level of antagonism against all the three strains of Macrophoma spp. followed by B. subtilis (72.9±0.6) and B. licheniformis (64.2±0.7). In culture filtrate studies also, B. amyloliquefaciens (80.2) was found to possess highest antagonistic activity against the test pathogen, followed by B. subtilis (74.8) and Pseudomonas fluorescens (69.0). Among these, one potent strain of B. amyloliquefaciens was taken for GC-MS study and their bioactive compounds were identified as 1H-indene, 1-methylene, 3-hexadecene (Z), benzene acetic acid, phenol, and caffeine. These compounds could be responsible for antifungal activity against branch canker pathogen

Bioefficacy of certain chemical and biofungicides against Hypoxylon spp. causing wood rot disease in tea

Wood rot disease caused by Hypoxylon serpens is the most widespread and serious stem disease in tea. Among the 350 bacterial and 35 fungal biocontrol isolates collected from several tea growing regions of southern India, three bacterial isolates produced higher antagonistic potential against this fungal pathogen. Two of the efficient strains were identified as Bacillus sp. (HBCWR-3 and WR46-2) and third one was Pseudomonas sp. (WR5-4). In case of fungal biocontrol agents, the type culture Trichoderma viride procured from Microbial Type Culture Collection (MTCC) performed better in controlling the pathogen over T. harzianum. Five systemic fungicides, hexaconazole, carbendazim, tebuconazole, tridemorph, benomyl and a contact fungicide, copper oxychloride were evaluated for studying their bioefficacy against wood rot pathogen. In this study, benomyl 50% WP or copper oxychloride at the lowest concentration (0.01%) completely inhibited the growth of the fungus in vitro. Moreover, bioefficacy of certain plant aqueous extracts of Azadirachta indica, acetone extracts of Pongamia pinnata, Cinnamom, Artemisia nilagirica, Lantana camera, Ageratum conyzoides and a bryophyte, Heteroscyphus argutus were also studied against H. serpens. Among them, A. nilagirica followed by H. argutus and A. indica were effective in controlling the wood rot pathogen. In the case of liquid biofungicides tested, ‘Expel’ controlled the tea pathogen efficiently. The present study revealed that, chemical fungicide (Benomyl or copper oxychloride at 0.01%), botanical extracts at 10% (A. nilagirica, H. argutus, Azadirachta and ‘Expel’) and biocontrol agents (Bacillus sp., Pseudomonas sp. and T. viride) were effective in controlling wood rot pathogen under in vitro condition

Vector rogue waves and dark bright boomeronic solitons in autonomous and non autonomous settings

In this work, we consider the dynamics of vector rogue waves and ark bright solitons in two component nonlinear Schrodinger equations with various physically motivated time dependent non linearity coefficients, as well as spatio temporally dependent potentials. A similarity transformation is utilized to convert the system into the integrable Manakov system and subsequently the vector rogue and dark bright boomeron like soliton solutions of the latter are converted back into ones of the original non autonomous model. Using direct numerical simulations we find that, in most cases, the rogue waves formation is rapidly followed by a modulational instability that leads to the emergence of an expanding soliton train. Scenarios different than this generic phenomenology are also reported

A special schedule of foliar application of nutrients for the tea fields under extensive mechanized harvesting

To overcome the problem of acute shortage of work force faced by the south Indian tea industry, UPASI Tea Research Institute recommends mechanized harvesting to cover large areas with high worker productivity. While adopting extensive mechanized harvesting, total leaf area of the maintenance foliage on the plucking surface is reduced. As a result growth of the crop shoots has been adversely affected leading to reduction in productivity. Excessive banji shoot formation and nutrient deficiency symptoms were also noticed. To overcome all these adverse impacts of extensive mechanization, foliar application of primary, secondary and micro-nutrients has been attempted. The practical utility of foliar feeding of all these nutrients when applied as a mixture after every harvest, except during continuous heavy rainy months, showed an increase in yield up to 21% compared to the current recommended practice, in spite of extensive harvesting using shears and machines. The problem of dwarfing of crop shoots due to extensive shear/machine harvesting could be minimized due to increase in internodal length by 0.87 cm and the dry weight of the crop shoots increased by 0.09 g/shoot. Excessive production of banji shoots also came down from 65 to 52%

Bioefficacy of efficient entomopathogenic fungus against branch canker pathogen (Macrophoma theicola) in tea plantations of southern India

Three branch canker pathogens, viz. NBCHE-6, UPA-61 and VPM were isolated from different tea growing districts of south India and four entomopathogenic fungus, viz. Beauveria bassiana, Paecilomyces lilacinus, Lecannicillium lecannii and Paecilomyces fumosoroseus were procured from the microbial type culture collection and gene bank (MTCC), Chandigarh. In vitro studies revealed that Beuveria bassiana showed highest antagonistic effect against NBCHE-6 (64.22) followed by Paecilomyces fumosoroseus against UPA-61(56.66). Paecilomyces lilacinus significantly controlled VPM (54.66), while Lecannicillium lecannii showed insignificantly control against VPM (47.33). While Beuveria bassiana and Paecilomyces lilacinus coiled around and shrink branch canker pathogen, Lecannicillium lecannii breaks into branch canker hyphae and Paecilomyces fumosoroseus produces more spore to kill branch canker. In culture filtrate studies, Paecilomyces fumosoroseus and Paecilomyces lilacinus showed maximum control of VPM (68.44) and UPA-61 (65.59). Beauveria bassiana also showed significant control of two isolates VPM and UPA-61 (54.44). Lecanniicillium lecannii showed least control of VPM (30.44). This study concludes that entomopathogens can significantly control branch canker pathogen (Macrophoma theicola)

Vector rogue waves and dark bright boomeronic solitons in autonomous and non autonomous settings

In this work, we consider the dynamics of vector rogue waves and ark bright solitons in two component nonlinear Schrodinger equations with various physically motivated time dependent non linearity coefficients, as well as spatio temporally dependent potentials. A similarity transformation is utilized to convert the system into the integrable Manakov system and subsequently the vector rogue and dark bright boomeron like soliton solutions of the latter are converted back into ones of the original non autonomous model. Using direct numerical simulations we find that, in most cases, the rogue waves formation is rapidly followed by a modulational instability that leads to the emergence of an expanding soliton train. Scenarios different than this generic phenomenology are also reported