Abstract: A process for biologically preventing dicotyledonous plant diseases which comprises: cutting a seedling of a dicotyledon which includes the seedling between a cotyledon and less than three leaves at a growth stage; immersing the upper portion of the cut seedling into a symbiotical bacteria suspension having antifungal and antibacterial activities and induced resistance to plant pathogens in order to inoculate the symbiotical bacteria into interior tissues in the vessel and intercellular space of the dicotyledonous plants; cutting the seedlings in a nursery bed or directly planting them in a field for further association of the symbiotical bacteria; and preventing dicotyledonous plant diseases of the dicotyledonous plants.

Abstract: A new Pseudomonas gladioli having the identifying characteristics of Bikohken-kin No. 8805 has been discovered. The microorganism is a new bacteria separated from a bulb and roots of Miltonia. For separation, the bulb and roots of Miltonia are ground in a 1% solution of peptone followed by a streak culture on a bouillon agar at 25.degree. C. for 48-96 hours, and the colonies thus grown are isolated. This microorganism is inoculated into a bulb and roots of a plant selected from the group consisting of Welsh onion, sorgo, oats and maize. The plants inoculated with the grown microorganisms are grown together within the radius of rhizosphere of a plant to be protected (or companion or mixed crop) for further multiplication of Pseudomonas gladioli M-2196 in order to control soil borne plant diseases caused by Fusarium oxysporum. Very strong antibacterial activity on Fusarium oxysporum, Rhizoctonia solani, Verticillum dahliae, Corynebacterium michiganese pv. michiganese, Sclerotium cepivorum etc. is observed.