CHARACTERIZATION OF Fusarium udum Butler CAUSING WILT OF PIGEON PEA AND ITS MANAGEMENT
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Date
2019-06
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JAU, JUNAGADH
Abstract
Pigeon pea (Cajanus cajan (L.) Mill sp.) popularly known as tur or arhar, a member belonging to family Fabaceae, believed to be originated in peninsular india is one of the most essential leguminous food crop cultivated in tropical and subtropical countries. It is the second most important pulse crop after chickpea, grown in India and plays an important role in subsistence agriculture. In India, major pigeon pea growing states are Maharashtra, Madhya Pradesh, Gujarat, Karnataka, Andhra Pradesh, Uttar Pradesh, Jharkhand, Orissa, Bihar and Rajasthan. Among them, Gujarat contains 9.06 lakh ha area with 9.03 lakh tones production, which contribute about 3 per cent area and 4 per cent production among the Indian states (Annon. 2017-18). Pigeonpea subjected to many diseases, among them, wilt caused by Fusarium udum Butler is the most important one.
The fungus isolated from infected plants grew as white thick cottony growth, with septate mycelia. Produced micro and macroconidia, also chlamydospores in old culture. Based on the morphological and cultural characters viz., mycelium, conidia, chlamydospores and growth characters the causal fungus of wilt in pigeonpea was identified as Fusarium udum Butler.
Pathogenicity of Fusarium udum was confirmed by reproducing the same symptoms like drooping of lower leaves, yellowing of leaves, interveinal chlorosis, loss of leaf turgidity and ultimately leading to death of entire plant. The plants showed
two types of wilting symptoms viz., complete wilting and partial wilting. The affected plants when longitudinally split opened showed brown to black vascular discoloration. Re-isolation confirmed the pathogenicity of Fusarium udum as the infected tissues produces the mycelia growth and conidial structures of the original fungus. Pathogenicity proved by different isolates of pathogen showed highest disease incidence in Isolate-2 which was collected from Bagdu villege (85.71 %).
All the agrochemicals tested were capable of inhibiting the mycelial growth of Fusarium udum at various concentrations as compared to control under in vitro condition. Among non-systemic fungicides, copper hydroxide 53.8 % DF and copper oxychloride 50 % WP were found to be the most effective fungicides, which gave 89.24 and 77.37 per cent mean mycelial growth inhibition, respectively. Mancozeb 75 % WP was the least effective fungicide with mean mycelial growth inhibition of 55.90 per cent mean mycelial growth inhibition. Whereas in systemic fungicides, carbendazim 50 % WP and tebuconazole 25.9 % EC were found most effective in mean reduction of radial growth of mycelium with inhibition of 87.39 and 85.35 per cent, respectively. Azoxystrobin 23 % SC recorded the least mean inhibition of mycelia growth with 64.79 per cent.
Among different combination fungicides tested, cymoxanil 8 % + mancozeb 64 % WP recorded cent per cent inhibition in all the tested concentrations and was found to be most effective under in vitro among all agro chemical used. In case of herbicides tested, quizalofo-p-pethyle 5 % EC proved as most effective inhibiting the mycelial growth with 76.20 mean per cent inhibition.
Among the seven biological control agents, Trichoderma harzianum and Trichoderma hamatum were found most effective in inhibiting the pathogen under in vitro condition. In case of in vitro antagonism Trichoderma harzianum and Trichoderma hamatum showed 79.63 and 74.63 per cent mycelia growth inhibition, respectively.
In pot culture experiment fungicide as well as bioagent are evaluated in net house. Among them, carbendazim 12 % + mancozeb 63 % WP was found most effective with least per cent disease incidence of 40 per cent. In case of bioagent Trichoderma harzianum and Trichoderma hamatum most antagonistic effect with disease incidence of 40 and 43.33 per cent, respectively.