['We addressed the process of immigration of Bacillus thuringiensis from soil to leaves and its capacity to grow on bean diffusate medium (BDM), a medium designed to simulate the nutrient composition of the phylloplane.', 'Two different B. thuringiensis strains were inoculated into soils, onto seeds or onto lower leaves of bean plants to determine if they were able to disperse to upper leaves under controlled conditions. While B. thuringiensis isolates were commonly recovered from leaves exposed to such inocula, populations were very low (<10 CFU cm(-2) of leaf). In addition, the number of cells of B. thuringiensis recovered decreased with increasing distance from the soil or from the inoculated leaves. Moreover, B. thuringiensis colonies did not grow well on BDM.'] Does immigration of Bacillus thuringiensis to bean leave from soil inoculum or distal plant parts?