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Ecofriendly management for fruit rot of chilli (Capsicum Annuum L.) caused by colletotrichum spp.
Chilli belonging to the family Solanaceae having Mexican centre of origin is an important spice cum vegetable crop grown for its pungent fruits. Besides being a rich source of spicy flavour and colour, they are free of cholesterol, low in sodium, rich in vitamin A, C, E, folic acid and potassium. I...
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| Format: | Ph.D Thesis |
| Language: | Undetermined |
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Vellayani
Department of Plant Pathology, College of Agriculture
2010
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| 245 | |a Ecofriendly management for fruit rot of chilli (Capsicum Annuum L.) caused by colletotrichum spp. | ||
| 260 | |a Vellayani |b Department of Plant Pathology, College of Agriculture |c 2010 | ||
| 502 | |b MSc | ||
| 520 | 3 | |a Chilli belonging to the family Solanaceae having Mexican centre of origin is an important spice cum vegetable crop grown for its pungent fruits. Besides being a rich source of spicy flavour and colour, they are free of cholesterol, low in sodium, rich in vitamin A, C, E, folic acid and potassium. India is a major producer, exporter and consumer of chilli. The area and production of chilli in the country is 7.57 lakh ha and 11.67 lakh tonnes. In Kerala, the area under cultivation is 14,000 ha with a productivity of 1000 Kg/ha. Chilli anthracnose / fruit rot was first reported in India by Sydow in the year 1913 from Coimbatore of erst while Madras Presidency. Anthracnose occurs both as pre harvest and post harvest decay of mature fruits and account for more than 50 % of the crop losses. Since 1940, chemical fungicides were used for the control of chilli diseases. The indiscriminate usage of a wide range of fungicides has invited many undesirable problems such as development of fungal resistance, toxic residues in the produce, environmental pollution and escalating costs in vegetable production. So there is an urgent need to find out an effective, alternative methods of disease control, which was less harmful to human beings and environment. The objective of the present investigation was to evolve an ecofriendly management strategy to control fruit rot of chilli using biocontrol agents, plant extracts and plant products. The study involves symptomatology of the disease under natural and artificial conditions. In both the situations, symptoms appeared as small brown sunken circular necrotic lesions with concentric rings of acervuli. The lesions enlarged elliptically and the fruit get shrivelled. During the present investigation, two species of Colletotrichum viz., C. gloeosporioides and C. capsici were isolated and the pathogenicity of the disease was proved. Conidial, morphological and cultural characters of both the organisms were studied. Conidia of C. gloeosporioides were cylindrical, straight with obtuse ends whereas that of C. capsici were falcate. Growth in different solid and liquid media, carbon sources, nitrogen sources, temperature and pH were studied. Best solid medium for the growth of C. gloeosporioides was Richards’ Agar whereas the best liquid medium was Richards’ broth, best carbon source - sucrose, best nitrogen source - Asparagine, best inorganic source - Potassium nitrate, optimum temperature 30˚С and optimum pH 6.0. Fungal antagonists obtained from the chilli phyllosphere were Penicillium sp., Aspergillus niger and from the rhizosphere Trichoderma harzianum, Gliocladium virens, Aspergillus flavus. Bacterial antagonists obtained from the rhizosphere was Bacillus sp. and Pseudomonas fluorescens. The best antagonist obtained under in vitro screening by dual culture technique T. harzianum, was selected for the in vivo study. Talc based formulation of T. harzianum was made and its shelf life was found to be more than 180 days. Leaf extracts at 60, 80 and 100 % concentrations from Piper betle, Ocimum sanctum, Azadirachta indica, Lantana camara, Datura stramonium, Andrographis paniculata and Bougainvillea glabra were tested against C. gloeosporioides under in vitro conditions by poisoned food technique and maximum inhibition of the pathogen was obtained in Datura stramonium at 80 and 100 % concentration. Lower concentrations of Datura stramonium were also tested (40, 20, 10 and 5 %) and it was found that as the concentration decreases, its effect is also found decreasing. Among the plant products viz., Turmeric powder, Garlic bulb extract, Neem Seed Kernel Extract and Neem oil tested against the pathogen, highest inhibition was obtained from Garlic bulb extract at 10 % concentration. Combinations of the biocontrol agent, plant extract and plant product were tested against the pathogen and it was observed that T. harzianum (1 %) + Datura stramonium (20 %) + Garlic bulb extract (10 %) completely inhibited the growth of C. gloeosporioides. Five chilli varieties released from KAU were screened against the disease and found that none of the varieties were found immune to the disease and the variety Vellayani Athulya was found to be the most susceptible one. This variety was selected for the in vivo management trial. For in vivo management of fruit rot of chilli a pot culture experiment in CRD with four replications and nine treatments was laid out at College of Agriculture, Vellayani. The treatments used were T. harzianum (1 %), Datura stramonium (20 %), Garlic bulb extract (10 %) individually and in combinations with standard fungicidal check Bavistin @ 0.05 % and unsprayed control. The variety Vellayani Athulya was used for the in vivo experiment. Among the treatments seedling dip with talc based formulation of T. harzianum 500 g per 1000 ml of water for 20 min. and two foliar sprays at five days interval with a combination of talc based formulation of T. harzianum @ 1 % + Datura stramonium leaf extract @ 20 % + Garlic bulb extract @ 10 % was found best for the management of fruit rot of chilli caused by C. gloeosporioides. | |
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