1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)

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Subject: search.filters.subject.Anthracnose

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    Mango varietal response to Anthracnose disease and its post-harvest management
    (Department of Plant Pathology, College of Agriculture , Vellayanikkara, 2025-02-15) Nikiru Lamare.; Radhakrishnan, N V
    The study entitled “Mango varietal response to anthracnose disease and its post-harvest management” was done to evaluate the incidence and severity of anthracnose in different mango varieties during post-harvest storage and assess the efficacy of certain post-harvest management techniques controlling anthracnose on the quality of fruits in different mango varieties. A survey was conducted in two agro-ecological units – 1 (Southern coastal plain) and 8 (Southern laterites) covering Kollam and Thiruvananthapuram districts. Mango varieties with anthracnose symptoms were collected from the surveyed locations, and pathogen isolates were obtained. The isolates were subjected to pathogenicity testing, morphological characterization, and virulence rating. The cultural and morphological studies showed that isolates displayed fluffy or sparse mycelial growth with white to grey pigmentation and had regular margins. The conidia of all isolates were oblong, dumbbell shaped, measuring 9.2 × 3.5 to 11.4 × 3.6 μm. Upon artificial inoculation on the fruits, the isolates showed the typical anthracnose symptoms, with black or brown sunken lesions. Upon virulent rating, it was revealed that isolate C10 proved to be the most virulent, with a lesion development rate of 1.30 cm/day and PDI of 46.67%. The virulent isolate was molecularly characterized with ITS primers and confirmed as Colletotrichum gloeosporioides (accession no. PQ475860) by phylogenetic analysis. Five mango varieties, Kottukonam, Neelum, Priyur, Rumani, and Totapuri, were obtained and subjected to screening by artificial inoculation of the anthracnose pathogen and assessed the varietal variation in symptom development, lesion growth and susceptibility. Symptoms were developed in 2 days for Kottukonam and Priyur, while Neelum, Rumani, and Totapuri showed symptoms after 3 days. Kottukonam showed the highest susceptibility with a PDI of 72.33%, while Totapuri had the lowest at 45.40%. In vitro evaluation of the antagonistic potential post-harvest management strategies against anthracnose pathogens was studied. Two bacterial cultures of Bacillus velezensis PCSE-10 and B. amyloliquifaciens VLY24 were obtained from the Department of Agricultural Microbiology. The dual culture assay of the biocontrol agents against the anthracnose pathogen revealed that B. amyloliquifaciens VLY24 showed 37.08% inhibition, while B. velezensis PCSE-10 had 32.87% inhibition. Poisoned food assay of carbendazim 50% WP against the pathogen revealed that 0.1% and 0.2% concentration showed 100% inhibition while 0.05% showed 76.67% inhibition. In vitro evaluation of bacterial suspension and cell free culture filtrate (CFC) of biocontrol agents against the pathogen mycelial growth at different concentrations showed that bacterial suspensions were more effective than CFC. In both the strains highest inhibition of mycelial growth was shown in the bacterial suspension of 100% concentration with 78.78% inhibition with B. amyloliquifaciens VLY24 and 76.83% inhibition with B. velezensis PCSE-10. The evaluation of various post-harvest management strategies for controlling anthracnose disease was conducted in five mango varieties in a two-factorial Completely Randomized Design (CRD). It revealed that the combination of hot water treatment (HWT) (52°C for 10 minutes) + B. amyloliquefaciens VLY24 (BA VLY24) (100% suspension) and carbendazim (CBZ) (0.1%) resulted in the lowest per cent disease index (PDI) of 17.04%, followed by the combination of HWT (52°C for 10 minutes) + B. velezensis PCSE-10 (BV PCSE-10) (100% suspension) + CBZ (0.1%), which had a PDI of 18.68%. Among the varieties, the lowest PDI was observed in Totapuri (38.26%), while the highest was recorded in Kottukonam (46.56%). Regarding total soluble solids (TSS), the combination of HWT+ BA VLY24 + CBZ recorded the lowest TSS content (12.86 °Brix). Across varieties, Priyur exhibited the highest TSS content (17.63 °Brix), followed by Neelum (14.65 °Brix). The effects of the interaction of treatments on lesion size and PDI across all varieties were not significantly different, which implies that treatments applied across all varieties have the same relative effect, whereas the impact on TSS varied significantly among varieties as TSS content varies with varieties. A combination treatment of hot water (52°C for 10 minutes) +B. amyloliquefaciens VLY24 (100% bacterial suspension) + Carbendazim 50% WP (0.1%) was applied to five mango varieties (Kottukonam, Neelum, Priyur, Rumani, and Totapuri). The response of treated fruits was compared with untreated controls. On the 7DAI, no symptoms were observed in treated fruits except for Kottukonam, whereas untreated fruits displayed symptoms as early as the 4th or 5th day. PDI was significantly higher in untreated fruits, with the highest PDI recorded in untreated Kottukonam (50.67%) and the lowest in untreated Totapuri (22%). Biochemical analysis revealed that peroxidase and polyphenol oxidase activities were higher in treated fruits than untreated ones on the 7 DAI. Treated fruits also exhibited an extended shelf life, and Totapuri recorded the longest duration (9.33 days). Physiological loss of weight was higher in untreated fruits than in treated fruits. Sensory evaluation revealed that treated fruits exhibited superior internal and external sensory quality in terms of appearance, colour, flavour, and overall acceptability. Among the varieties, Totapuri received the highest overall acceptability score of 8.08. Biochemical assessments indicated that treated fruits had higher titratable acidity whereas, total soluble solids (TSS) and reducing sugar content were lower in treated fruits across all varieties tested. This study concluded that C. gloeosporioides was the pathogen responsible for mango anthracnose. Among the varieties, when subjected to screening by artificial inoculation, it revealed that Kottukonam was the most susceptible mango variety, followed by Priyur, while Totapuri was the least susceptible, followed by Rumani and Neelum. Effective post-harvest management of mango anthracnose can be achieved using a combination of hot water treatment (52°C for 10 minutes), B. amyloliquefaciens VLY24 (100% suspension), and carbendazim 50% WP (0.1%).
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    Ecofriendly management of major fungal foliar diseases affecting yard long bean in polyhouse
    (Department of Plant Pathology, College of Agriculture, Vellayani, 2019) Deepthi Nair, S; Sajeena, A
    The study entitled ‘Ecofriendly management of major fungal foliar diseases affecting yard long bean in polyhouse’ was conducted at College of Agriculture, Vellayani and Integrated Farming System Research Station (IFSRS), Karamana during 2017- 2019 with the objectives to determine the major fungal foliar diseases affecting yard long bean grown in polyhouse; and their management using natural resources and ecofriendly methods. A survey was conducted in 15 polyhouses located at different parts of Thiruvananthapuram district, where yard long bean was cultivated. NS 621 was the most common variety of yard long bean cultivated in polyhouses. Powdery mildew (Disease Incidence (DI) - 100% and Per Cent Disease Index (PDI) - 60.70) and Diaporthe leaf spot (DI - 80% and PDI - 45.77) were the major fungal foliar diseases of the crop observed in these polyhouses. Five varieties of yard long bean viz. Lola, Vellayani Jyothika, Gitika (KAU Varieties), VS 50 (KAU pre release culture) and NS 621 (Namdhari Seeds Private Limited) were screened in the polyhouse at IFSRS, Karamana in completely randomized design (CRD) with four replications, to assess the natural incidence and severity of different fungal foliar diseases. The most susceptible variety to natural incidence of powdery mildew (PDI - 50.89) and Diaporthe leaf spot (PDI - 58.66) diseases was NS 621, whereas VS 50 was tolerant to powdery mildew disease (PDI - 11.11). In vitro evaluation of organic preparations viz, egg-lemon juice extract (10%) and sunflower oil (25 ml) + baking soda (10 g) + bar soap (10 g) + water (5 l), botanicals viz. fermented weed (Setaria barbata) extract (10%) and nimbecidine (0.5%), and non-hazardous compounds viz. potassium silicate (1%) and sodium bicarbonate (0.5%) against Diaporthe tulliensis by poisoned food technique in potato dextrose agar (PDA) medium revealed that fermented extract of S. barbata (10%), sodium bicarbonate (0.5%) and a combination of egg-lemon juice extract (10%) and fermented extract of S. barbata (10%) resulted in cent per cent inhibition of the mycelial growth of the fungus, which were further used for in vivo evaluation. Fermented egg-lemon juice extract (10%), potassium silicate (1%) as well as Psuedomonas fluorescens (KAU isolate) had no inhibitory effect on the mycelial growth of the fungus. A trial was conducted to assess the efficacy of selected treatments for the management of powdery mildew and Diaporthe leaf spot diseases in NS 621 in the polyhouse of IFSRS, Karamana in CRD with eight treatments replicated thrice. The plants sprayed with tebuconazole 50% + trifloxystrobin 25% (WG) (0.04%) (positive control) at 20, 40 and 60 days after planting (DAP) resulted in maximum control of Diaporthe leaf spot (PDI - 4.89) and powdery mildew (PDI - 1.22) diseases. Among the treatments, the combined application of arbuscular mycorrhizal fungi (AMF) (KAU isolate) @ 5g plant-1 at the time of planting along with the foliar application of fermented extract of S. barbata (10%) at 20, 40 and 60 DAP resulted in significant control of Diaporthe leaf spot (PDI - 11.35), whereas the combined application of AMF @ 5g plant-1 at the time of planting along with the foliar application of sodium bicarbonate (0.5%) at 20, 40 and 60 DAP resulted in significant suppression of powdery mildew disease (PDI -11.59). Soil application of AMF alone and foliar application of P. fluorescens (2%) had least effect in reducing the severity of both the diseases. Thus, the present study revealed that powdery mildew and Diaporthe leaf spot were the most important diseases of yard long bean in polyhouses of Thiruvananthapuram district. Soil application of AMF @ 5g plant-1 at the time of planting and foliar spray of fermented extract of S. barbata (10%) or sodium bicarbonate (0.5%) at 20, 40 and 60 DAP were the most effective treatments against Diaporthe leaf spot and powdery mildew diseases respectively, which could be used as a green technology to produce safe-to-eat yard long bean.
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    Prediction of SSR and SNP markers for anthracnose resiistance in YAM using bioinformatics tools and their validation
    (Department of Plant Biotechnology, College of Agriculture, Vellayani, 2018) Sahla, K; Sreekumar, J
    The study entitled “Prediction of SSR and SNP markers for anthracnose resistance in yam using bioinformatics tools and their validation” was conducted at ICAR-Central Tuber Crop Research Institute, Sreekariyam, Thiruvananthapuram during October 2107 to August 2018. The objectives of the study is to computationally identify SNPs and SSRs for anthracnose resistance in Greater Yam and the verification of identified markers using resistant and susceptible varieties. The preliminary data set for the identification of SSR and SNP markers was obtained from the EST section of NCBI. A total of 44134 sequences was obtained. The dataset was reduced to 44114 sequences after several pre-processing and screening steps. The resulting sequences were assembled and aligned using CAP3 and 5940 contigs were obtained. SNPs and SSRs were predicted from these datasets using respective prediction tools. The SNP prediction tools such as QualitySNP and AutoSNP were compared for their performance. Analysis was performed to identify the tool with the ability to annotate and identify more viable nonsynonymous and synonymous SNPs. For SSRs the SSR prediction tools such as MISA and SSRIT was compared and analysis was performed to identify the tool having the ability to predict more viable SSRs and the ability to classify them as mono, di, tri, tetra, penta, hexa and poly SSRs. Using QualitySNP, 1789 nonsynonymous SNPs and 73 synonymous SNPs were identified. Using MISA, 359 mono SSRs, 268 di SSRs, 342 tri SSRs, 17 tetra SSRs, 7 penta SSRs, and 9 hexa SSRs were identified. Five sequences from identified SNPs and SSRs which having high hit percentage and low E value were selected for validation and primer designing for anthracnose resistant genes. These primers were validated using 3 resistant and 3 susceptible yam varieties. Among the primers after validation in wet lab, three SNPs (DaSNP1, DaSNP2, DaSNP3) and two SSRs (DaSSR1 and DaSSR2) primer was able to clearly differentiate between the resistant and susceptible varieties which can be used as potential markers in the breeding program for screening anthracnose resistance in yam.
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    Integrated management of anthracnose of snake gourd (Trichosanthes cucumerina L.)
    (Department of Plant Pathology,College of Agriculture, Vellayani, 2016) Aswani Devi; Kamala Nayar
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    Triazole,strobilurin and its combination fungicides for the management of anthracnose and fruit rot of chilli
    (Department of Plant Pathology, College of Agriculture, Vellayani, 2018) Anjana, R S; Joy, M
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    Ecofriendly management of anthracnose of betel vine (piper betle L.)
    (Department of Plant Pathology, College of Agriculture, Vellayani, 2018) Nisha, A; Heera, G
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    Evaluation of biofilm based microbial antagonists for the management of soil borne diseases and growth promotion in cowpea (Vigna unguiculata L. Walp)
    (Department of Agricultural Microbiology, College of Horticulture, Vellanikkara, 2018) Vinay Kumar, B; Surendra Gopal, K