MSc

The study entitled "Ecofriendly management of anthracnose of betel vine" was conducted during 2016-18 at Department of Plant Pathology, College of Agriculture, Vellayani with an objective to evolve an integrated management strategy involving organic preparations, bio control agents and new generation fungicides for anthrancnose of betele vine.
A survey was conducted in different locations in Southern Kerala viz., Thiruvananthapuram (Kalliyoor, Vellayani and Kattakada), Kollam (Kareepra), and Alappuzha (Cherthala) regions during 2016-18. Anthracnose was the major problem in these areas. The highest percentage disease index of 20.00 was observed from Cherthala region of Alappuzha. The symptoms of the anthracnose appear as small necrotic spots with a yellow halo on the leaf lamina mostly starting from the margin of the leaf. These lesions coalesce together results in leaf blighting and defoliation. Under high humid conditions, stem lesions were also produced which resulted in drying of the entire vines. Colletotrichum sp. was found to be associated with the disease in five locations. Isolations were made and five pure cultures of Colletotrichuym sp. (C1 to C5) were obtained and its pathogenicity was proved using Koch's postulates.
Culture and morphological characters of the five different isolates were studied. The isolated cultures of Colletotrichum sp. produced whitish to dark grey, orangish to off white coloured colony having fluffy to sparse mycelial growth with regular margins. The different isolates took 7-9 days for completion of growth in petri dish. The mycelium of the fungus was hyaline,septate and width ranged from 2.65 - 3.45µm. The septal distance varied from 9.80 - 25.56 µm. The conidia were single celled with an oil globule and the shape varied from cylindrical, oblong to dumbbell among the isolates. The condial and appressorial size varied from 9.6-12.2 µm *3.8 - 4.7 µm and 8.37 - 10.08µm *5.02-6.28µm.
The pathogenic variability among the five different isolates were assessed by virulence rating. The isolate C2 was identified as most virulent which produced lesion size of 14.75 mm at 5 days after inoculation (DAI). The isolate C2 initiated symptom within two days of artificial inoculation having a rate of lesion development of 2.95 mm day-1. The identity of C2 isolate as C. gloeosporioides was confirmed by the use molecular techniques (DNA barcoding).
The indigenous organic preparations viz., panchagavya, jeevamruth, vermiwash and fermented cow’s urine at 5 and 10 per cent (autoclaved and non-autoclaved) were evaluated for in vitro pathogen suppression. The micronbial population was estimated at 1, 5 and 7 days in the filtered and non-filtered indigenous organic preparations. Microbial population of bacteria was comparatively high in these organic preparations when compared to fungi. The bacterial population showed an increasing trend in non-filtered organic preparations except jeevamruth. The mycelial nature in amended media varied from fluffy to sparse growth with uniform or irregular growth pattern under autoclaved and non-autoclaved extracts of organic preparations.
Panchagavya at 10 per cent and fermented cow's urine at 5 percent and 10 perecent (non-autoclaved) completly inhibited the pathogen. Autoclaved fermented cow’s urine at 5 pere cent and 10 per cent failed to inhibit the mycelial growth of the pathogen. The autoclaved and non-autoclaved organic preparation panchagavya at 10 per cent was more effective than other treatments in inhibiting the mycelial growth of the pathogen.
The saprophytic micro flora were isolated form the rhizosphere and phyllosphere of healthy betel vine. The fungal and bacterial biocontrol agents from phyllosphere and rhizosphere were screened in vitro for pathogen suppression. The fungal antagonist Trichoderma 1 was superior in inhibiting the mycelial growth of C. gloeosporioides. Among the bacterial isolates screened, the isolate B5 from the phyllosphere of the healthy betel leaves had a higher percentage of mycelial inhibition (45.00 per cent).
Screening of fungicides against the fungal pathogen under in vitro condition revealed that systemic fungicides (Propiconazole, tebuconazole), combination fungicides (captan + hexaconazole and carbendazim + mancozeb) at 0.05, 0.1 and 0.2 per cent completely inhibited the mycelial growth of the pathogen. The contact fungicide copper hydroxide was also effective inhibiting the mycelial growth. The fungicide Propiconazole was effective in suppressing complete growth of the pathogen at lower dose of 0.01 per cent (100 ppm).
A pot culture study was laid out in CRD with 8 treatments in 4 replications to develop an integrated management package. The effective treatments of the above studies viz., panchagavya (10 per cent), bacterial isolate (B5-108 cfu/ml), propiconazole (0.1 per cent), copper hydroxide (0.2 per cent)carbendazim and mancozeb (0.2 per cent) and chemical control check (Bordeaux mixture - 0.5 per cent) with inoculated and un inoculated control were evaluated for the management of anthracnose of betel vine. The treatment of propiconazole was superior in reducing the percentage disease index and disease incidence. The treatment recorded a disease index of 19.99 per cent at 10 days after second spry with 74.99 per cent disease suppression over rinoculated control. The second best treatment was the foliar application of carbendazim + mancozeb (0.2 per cent) which was on par with copper hydroxide (0.2 per cent) in reducing the severity of the disease. Even though the chemicals were far more effective in managing the disease, the bacterial isolate B5 was equally effective in suppressing the pathogen with 46.24 per vent disease suppression over inocu;lated control with d disease index of 42.98. The biometric observations did not show significant difference among the different treatments except the number of leaves.
The present study reveals that all the fungicides and bacterial isolate from phyllosphere were effective in managing the disease over the traditional management using Bordeaux mixture at 0.05 per cent POP of KAU, 2016 since it is a masticatory crop need based application of antagonistic bacteria may be suggested for the anthracnose management in betel vine. For proper disease management approach, the bacterial antagonist may be suggested after conducting further studies on the spray schedule, dosage compatibility with fungicides and its biosafety.