Bacteria from the rhizoplane and surrounding soil of healthy and
Rhizoctonia solani diseased tomato plants, cropped in greenhouse of
the V Region of Chile, were collected. The best bacterial strains,
based on their ability to control development of three R. solani
isolates (identified as belonging to the anastomosis groups AG-2-1,
AG-4), were identified as B. subtilis (one isolate) and B.
lentimorbus (two different isolates). All bacterial isolates resulted
effective for the in vitro control of growth of all R. solani isolates,
where the control mechanisms used by the bacteria do not involve the
secretion of fungal cell wall hydrolytic enzymes. R. solani AG-2-1 was
more sensitive than R. solani AG-4. On the other hand, all bacteria
grew well in conditions similar to those that can be found at the field
level (considering pH, salinity, Fe3+ and temperature) and showed a
good capacity of tomato root colonization. These results suggest that
the B. subtilis and B. lentimorbus isolates studied have an excellent
potential to be used as biocontrol agents of R. solani in tomato
greenhouses at the field level