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A study was conducted under field condition in microplots to explore the feasibility of using certain fungal and bacterial phosphate solubilizing microoganisms (PSMs) through soil application and root-dip treatment to manage wilt of tomato caused by Fusarium oxysporum f. sp. lycopersici. Aspergillus awamori and A. niger were cultured on potato dextrose broth, whereas Pseudomonas fluorescens and P. striata were cultured on nutrient broth. Inoculum of the wilt fungus was prepared on sorghum seeds and was added to soil at 2 g/kg soil. For soil application of PSMOs pure culture on the broth was diluted in ample water and added to soil at 2 ml/kg soil. For root-dip treatment, roots of tomato seedlings, Lycopersicon esculentum cv. Pusa Ruby were dipped in the pure broth culture of the microorganisms for 30 min. The seedlings were planted in the microplots (3×2 m) in the presence or absence of wilt fungus. The pathogenic fungus caused characteristic symptoms of wilt and significantly decreased the shoot dry weight and the yield by 36.6% and 34.7%, respectively. Soil application of A. awamori or P. fluorescens improved the yield of tomato (without wilt fungus) by 22% and 9%. Root-dip treatment with the former also improved the yield significantly. Application of PSMs, in general, suppressed the wilt fungus to a varied extent and decreased the wilt severity being greatest with A. awamori (29-37%). Fungicide treatment (carbendazim) decreased the severity of wilt by 8-19%. Greatest increase in the yield of infected plants was recorded due to soil or seed treatment with A. awamori (15-20%), followed by P. fluorescens (11-16%) and carbendazim (12-19%) compared to inoculated control. Soil population of wilt fungus (CFUs/g soil) in untreated plots was increased during first 2 months. Whereas in bioagent or fungicide treated plots, the population was gradually and significantly decreased during the 4 months of plant growth period. Greatest decrease in the population was recorded with A. awamori, followed by A. niger, P. fluorescens and carbendazim. On overall basis, soil application was found 5-10% more effective than root-dip treatment. [ABSTRACT FROM AUTHOR]

Bacillus subtilis, B. polymyxa, Pseudomonas fluorescens and P. stutzeri were cultured on nutrient broth and were applied on the seeds of mungbean at 5 mL/kg of seeds along with the rhizobium. The seeds were sown in microplots (3×1.5 m) where nematode suspension (1500 second stage juveniles of Meloidogyne incognita/kg soil) had already been added or not added. Three microplots which were randomly distributed in the field were maintained for each treatment. In the plots without nematodes, plants showed better growth with significantly improved yield, especially with P. stutzeri. Root-nodulation was significantly increased due to the treatments of P. stutzeri or B. polymyxa compared to uninoculated control. Inoculation with the nematode caused severe galling on roots and decreased the yield of mungbean by 23.8%. Application with P. fluorescens or B. subtilis suppressed the gall formation, reproduction and soil population of M. incognita. The nematicidal effect of the PSMs was considerably less than the fenamiphos treatment (at 2 g/kg seed). Rhizosphere population of all PSMs tested was significantly increased over time irrespective of nematode presence or absence. Application of P. fluorescens suppressed the nematode pathogenesis and increased the yield of mungbean by 30.9% that was greater than the nematicide treatment (16.7%). [ABSTRACT FROM AUTHOR]