Studies on the incidence and management of guava decline involving root-knot nematode and fungi
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Date
2019-11
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CCSHAU, Hisar
Abstract
The present investigation was conducted for the incidence and management of guava decline caused by root-knot nematode, M. incognita and fungus, F. oxysporum f.sp. psidii, in Haryana. The survey results of Hisar, Jind, Sirsa and Fatehabad districts of Haryana revealed the occurrence of nine phytonematode genera and three fungal genera from infected guava orchards. Among them, M. incognita and F. oxysporum f. sp. psidii were predominant pathogens involved in causing guava decline. The maximum frequency of occurrence of M. incognita was recorded in Fatehabad (72.2%), followed by Hisar (63.2%), Jind (56.3%) and Sirsa district (53.3%). Among four districts surveyed, the mean of guava decline incidence was maximum in Jind (51.6%) followed by Sirsa (49.4%), Hisar (40.4%) and Fatehabad district (36.6%). The experiment on pathogenicity of M. incognita revealed that the significant reduction of plant variables were observed at the inoculum level of 1000 j2 and onwards and which was considered to be pathogenic level to guava plants. The pathogenicity of F. oxysporum f. sp. psidii on guava seedlings was proved and inoculum level of 6g mycelium/kg soil was considered to be pathogenic level to guava plants. The interaction of M. incognita and F. oxysporum f. sp. psidii showed that the statistically lowest plant growth parameters were recorded in nematode 10 and 20 days prior to fungus and the significantly lowest nematode reproduction factors were recorded in fungus 20 and 10 days prior to nematode inoculation. Significantly highest root rot was observed in plants inoculated with M. incognita 10 days prior to inoculation of F. oxysporum f.sp. psidii (43.67%) followed by nematode 20 days prior to fungus (39.34%). The incorporation of deoiled cakes viz., neem and mustard cake @ 30g/kg soil enhanced plant growth parameters and reduced the nematode reproduction factors irrespective of individual or combined inoculation of M. incognita and F. oxysporum f.sp. psidii. Among different bio-agents tested, the treatments receiving combined formulation of T. viride, P. fluorescens and P. lilacinum @ 10ml/kg soil recorded maximum plant growth parameters and minimum nematode reproduction factors irrespective of whether individual or combined inoculation of M. incognita and F. oxysporum f.sp. psidii.