Abstract
It was found that a 0.3mcg/ml water solution of streptomycin at first inhibits the growth and later causes the death of Ps. solanacearum, while a concentration of 1mcg/ml is required to inhibit the growth of Ps. tabaci which can be sometimes resumed later. Both bacteria were killed at once by 5mcg/ml solution.
And the writers have studied surface absorption of streptomycin in tobacco plants from various points of view, namely absorption in various plant organs, absorption amount and concentration, absorption and surface active agents, absorption and light, absorption rate and streptomycin injury to the plant.
It was found that amount of streptomycin absorbed by the lower surface of a leaf is twice as large as that absorbed by the upper surface. The higher the concentration the larger amount of streptomycin is absorbed but from a certain limit upwards the injury inflicted upon the plant increases. By adding as a surface active agent 0.1% Tween 20 the absorption was improved and the difference between the lower and the upper leaf surface became smaller. The maximum of absorption was reached 8 hours after spraying. There was no correlation between light and absorption. The plants could recover when the injury was not severe.
