A Study of some Powder Formulations of Pseudomonas fluorescens P4 for the Control of Sunflower Sclerotinia Root Rot Caused by Sclerotinia sclerotiorum

Seven antagonistic bacteria belonging to Pseudomonas fluorescens species were evaluated on the basis of inhibitory zone of Sclerotinia sclerotiorum fungal growth Finally, the most suitable strain (P4) which exerted the greatest effect on reducing the causal agent of Sclerotinia root rot was selected for further germinator trails. Nine formulations were prepared on the basis of talc powder from the strain P. fluorescens P4. Three culture mediums: M1, NBY and KB; along with three stickers: gum arabic, xunthan gum and carboxy methyl cellulose were used in these formulations. A survey of the effect of the formulations as regards the control of Sunflower Sclerotinia root rot was done on Progress variety of Sunflower and in germinator. Studies after six weeks past, indicated that, treated pots with free cell bacteria, with 100 percent healthy plants, treated pots with Bordofix fungicide containing 90 percent healthy plants, treated pots with NBY-CMC, KB-CMC, NBY-XG, NBY-AG and M1-CMC formulations with 87.5 percent healthy plants as well as treated pots with M1-AG formulation with 75 percent healthy plants, without any significance of difference as compared with healthy control plants, led to the most diminishing percentage being even more effective than Bordofix fungicide bearing a 62.5 percent of healthy plants. Furthermore, among powder formulations, the survival and maintenance of the population of bacteria in M1 culture medium with gum arabic sticker, at 4o C was more pronounced than those in the other formulations, during 150 days. Thus, the type of culture medium proved to have a significant impact on survival of the bacteria population.