Biocontrol of wilt disease complex of pigeon pea, caused by Meloidogyne incognita, Heterodera cajani and Fusarium udum, was studied using 21 isolates of fluorescent Pseudomonads isolated from pathogen suppressive soils. The isolates Pf 718, Pf 719 and Pf 736 of Pseudomonas fluorescens and Pa 737 of P. aeruginosa caused 79, 84, 87 and 93% reductions in hatching of M. incognita, and showed inhibition in the growth of F. udum in the dual inoculation. Isolate Pf736 caused 309, 9 and 78% increases in seedling growth, phosphate solubilization and IAA production respectively and also showed moderate HCN production. Isolate Pa737 was the best to colonize roots of pigeon pea followed by Pf736. The effects of these four isolates (Pf718, Pf719, Pf736 and Pa737) were studied on the wilt disease complex both in mono and multi-pathogenic combinations. The isolates Pf736 caused greater increase in plant growth and higher reduction in nematode multiplication and wilting index followed by Pa737, Pf718 and Pf719. The use of these isolates along with Rhizobium (pigeon pea strain) further increased plant growth and reduced nematode multiplication and wilting index. Twelve isolates production of siderophores in Chrome Azurol S (CAS) agar medium. The results suggest that P. fluorescens Pf736 along with Rhizobium may be used for the management of wilt disease complex of pigeon pea.
Keywords: Fusarium udum, Heterodera cajani, Meloidogyne incognita,Pseudomonas aeruginosa, P. fluorescens, rhizobium.
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