Studies on Management of Chickpea Wilt Pathogen Fusarium Oxysporum F.sp. Ciceri

Abstract

Pulses are important ingredient in the diet of a vast majority of Indian population as they provide a perfect mixture of high biological value when· supplemented with cereals. Besides their dietary value and Nitrogen fixing ability, pulses also play an important role in sustaining intensive agriculture by improving physical, chemical and biological properties of soil and are considered excellent crops for diversification of cereal based cropping system. Chickpea (Cicer arietinun L.) is an important pulse crop in India. Despite the introduction of high yielding varieties and improved cultural practices, production of chickpea per unit area is considerably low. A few diseases of this crop which were of minor importance, now have assumed serious, proportion and several new diseases have come into prominence. The Fusarium wilt of chickpea is one of such diseases. During the investigations, the diseased plants were brought to the laboratocy and the pathogen was isolated on potato dextrose agar medium (PDA). The isolations yielded the fungus Fusarium oxysponm1 f.sp. ciceri. Pathogenicity tests were carried out to examine the pathogenic behavior of the isolated fungus. In pathogenicity test, it produced similar symptoms as observed in naturally infected cropped diseased plants. In this way, isolation, inoculation andre-isolation of the same fungus proved the Koch's postulates. Trichoderma harzianum in presence of two growth regulators namely Gibberellic Acid (GA3) and Indole Acetic Acid at the conc::entration 30 ppm. was effective while Trichoderma virens was found effective at 30 for Gibberellic Acid (GA3) and 15 ppm for Indole Acetic Acid (IAA) to control the Fusarium oxysporum f.sp. ciceri in dual culture method. The maximum inhibition (16.11 %) was observed at 6 pH, level of media however maximum radial growth (69.00 mm) of Trichoderm virens was noticed at 7 pH in dual culture at eight days after inoculation. In bio-assay method during inv.estigatton, extracts of garlic bulb (Allium sativum), onion bulb (Allium cepa), leaves of eucalyptus (Eucalyptus globulus), Lamana camera and turmeric (Curcuma longa) and seeds of mustard (Brassica compestris) (all at 15% WN) were evaluated against the pathogen. All the' plant extra--cts were effective in inhibition of the mycelial growth but maximum (43.33 %) inhibition in colony growth of the pathogen was observed with bulb extract of garlic (Allium sativum) followed by bulb extract of onion (Allium cepa), with 41.8§% inhibition of test pathogen. The fungieides Carbendazim and Thiram were highly toxic to Fusarium oxysporum f.sp. ciceri concentration with 100% inhibition of test pathogen at 0.2% concentration in poisoned food technique. The least effective fungicides was Kavaeh (with 66.67 %) inhibition in-vitt: against Fusarium oxysporum f.sp.ciceri at eight days after inoculation.