THE CONTROL OF DISEASES OF LETTUCE BY THE USE OF ANTAGONISTIC ORGANISMS I. THE CONTROL OF BOTRYTIS CINEREA PERS.

The antagonism of a number of bacteria, actinomycetes and fungi to Botrytis cinerea in pure culture on lettuce extract agar has been investigated. A considerable number were antagonistic at 25° C., a few showed antagonism at 15° C. and a limited number grew and were active at 5° C.
Certain of these organisms were able to control rot of detached lettuce leaves when inoculated before or simultaneously with B. cinerea. The latter is unable to penetrate areas of dead tissue colonized by selected antagonists.
Control of rot was also obtained when leaves of growing plants were similarly inoculated.
Substantial control of disease occurred when young potted plants in frames were sprayed with suspensions of selected antagonists in 1.0 % glucose solution.
The practicability of this method of control is discussed.