Concurrent emergence of exotic whitefly incursions on arecanut (Areca catechu L.) in India

Field incidence of exotic whitefly complex comprising two Neotropical nesting whiteflies viz., Paraleyrodes bondari Peracchi and Paraleyrodes minei Iaccarino, in association with invasive rugose spiralling whitefly Aleurodicus rugioperculatus Martin and native areca whitefly, Aleurocanthus arecae David & Manjunatha, on arecanut was reported from Karnataka, India during 2020. These arecanut palms were previously infested by A. arecae which was earlier reported from Karnataka during 2003. To our knowledge, this is the first report on the infestation of P. bondari and P. minei on arecanut as highlighted in this current investigation. Morphological identification based on pupal taxonomy and male genitalia as well as molecular characterization of the mitochondrial cytochrome oxidase I (COI) gene confirmed the identity of nesting whiteflies. The Bondar’s nesting whitefly, P. bondari is the most predominant whitefly species with 87.5 per cent active colonies followed by the nesting whitefly, P. minei (13.64%) and the rugose spiralling whitefly, A. rugioperculatus (6.25%). Co-occurrence of these three non-native whitefly species on arecanut in synergy with the native A. arecae indicates a kind of competitive regulation of one species over the other upsetting biodiversity. Due to the polyphagous nature of the pest coupled with increased trade and transport in a climate change scenario, this whitefly complex may become a serious threat to arecanut production in India and elsewhere. This requires strict quarantine protocols to avert its spread to other arecanut growing areas

Timing of oomycete-specific fungicide application impacts the efficacy against fruit rot disease in arecanut

Fungicidal application has been the common and prime option to combat fruit rot disease (FRD) of arecanut (Areca catechu L.) under field conditions. However, the existence of virulent pathotypes, rapid spreading ability, and improper time of fungicide application has become a serious challenge. In the present investigation, we assessed the efficacy of oomycete-specific fungicides under two approaches: (i) three fixed timings of fungicidal applications, i.e., pre-, mid-, and post-monsoon periods (EXPT1), and (ii) predefined different fruit stages, i.e., button, marble, and premature stages (EXPT2). Fungicidal efficacy in managing FRD was determined from evaluations of FRD severity, FRD incidence, and cumulative fallen nut rate (CFNR) by employing generalized linear mixed models (GLMMs). In EXPT1, all the tested fungicides reduced FRD disease levels by >65% when applied at pre- or mid-monsoon compared with untreated control, with statistical differences among fungicides and timings of application relative to infection. In EXPT2, the efficacy of fungicides was comparatively reduced when applied at predefined fruit/nut stages, with statistically non-significant differences among tested fungicides and fruit stages. A comprehensive analysis of both experiments recommends that the fungicidal application can be performed before the onset of monsoon for effective management of arecanut FRD. In conclusion, the timing of fungicidal application based on the monsoon period provides better control of FRD of arecanut than an application based on the developmental stages of fruit under field conditions

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Not AvailableTrichoderma asperellum is well-known for the biocontrol activity against diverse plant pathogens. Various cell wall degrading enzymes viz. chitinases, glucanases and proteases are produced by T. asperellum against plant pathogens. Chitinases are the main class of enzyme that operate against fungal pathogen cell wall. In the present study, a total of three different chitinase genes viz. Chit42, Chit2 and ChitB were cloned and characterized from T. asperellum strain Ta13. The phylogenetic analysis of three different chitinase gene sequences formed separate cluster among themselves. Sequence similarity analysis of the nucleotide and amino acid sequences showed the uniqueness and distinct nature of the amplified chitinase genes. Maximum chitinase activity (93.5 mg/ml NAGA concentration) revealed that Ta13 is an efficient chitinase producer which acts against agriculturally important pathogens.Not Availabl

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Not AvailableMicrobes that colonize internal tissues of plants are called endophytes, andare known for their functional role against biotic/abiotic stress and growth promotion activity in plants. The ascomyceteous fungus Trichoderma spp. (Teleomorph: Hypocrea) are well known antagonists cum biocontrol agents. In this study, a total of five Trichoderma isolates from two different species viz., T. asperellum (TaR1, TaR2 and TaR3) and T. asperelloides (TaR4 and TaR5) collected from different agro-climatic zones in Rajasthan, India were evaluated for their endophytism in rice variety Pusa Basmati-1 (PB-1) through soil and seed treatment. An attempt was made to re-isolate the fungus from rice roots (seed and soil treated) and further subjected to microscopic and molecular analysis. Re-isolation results revealed that culture growth of Trichoderma spp. isolated was similar to that of the inoculated ones. The microscopic analysis (light and scanning electron microscopy) results also confirmed that the re-isolated endophytic fungus were identical to the inoculated ones. These results were further confirmed by polymerase chain reaction (PCR) amplification of the rDNA region (18SrRNA, ITS1, 5.8SrRNA, ITS2 and 28SrRNA) and translation elongation factor 1 (Tef1) with the re-isolated Trichoderma asperellum and T. asperelloides isolates. In this study, it has been confirmed that Trichoderma asperellum and T. asperelloides turns endophytic in rice after introduction through seed and soil treatment.Not Availabl

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Not AvailableNot AvailableDirectorate of Cashew and cocoa development, Cochi

Opportunistic endophytism of <em>Trichoderma</em> species in rice Pusa Basmati-1 (PB1)

121-128Microbes that colonize internal tissues of plants are called endophytes, andare known for their functional role against biotic/abiotic stress and growth promotion activity in plants. The ascomyceteous fungus Trichoderma spp. (Teleomorph: Hypocrea) are well known antagonists cum biocontrol agents. In this study, a total of five Trichoderma isolates from two different species viz., T. asperellum (TaR1, TaR2 and TaR3) and T. asperelloides (TaR4 and TaR5) collected from different agro-climatic zones in Rajasthan, India were evaluated for their endophytism in rice variety Pusa Basmati-1 (PB-1) through soil and seed treatment. An attempt was made to re-isolate the fungus from rice roots (seed and soil treated) and further subjected to microscopic and molecular analysis. Re-isolation results revealed that culture growth of Trichoderma spp. isolated was similar to that of the inoculated ones. The microscopic analysis (light and scanning electron microscopy) results also confirmed that the re-isolated endophytic fungus were identical to the inoculated ones. These results were further confirmed by polymerase chain reaction (PCR) amplification of the rDNA region (18SrRNA, ITS1, 5.8SrRNA, ITS2 and 28SrRNA) and translation elongation factor 1 (Tef1) with the re-isolated Trichoderma asperellum and T. asperelloides isolates. In this study, it has been confirmed that Trichoderma asperellum and T. asperelloides turns endophytic in rice after introduction through seed and soil treatment

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Not AvailableNot AvailableDirectorate of Cashewnut and Cocoa Development (DCCD), Koch