Studies on the Residual Effect of Fungicide (Preliminary Report)

Abstract

In the factor affected to the residual effect of agricultural chemicals, the flowing down by rain is an important one. So, in this experiment, the authors examined the residual effect of some fungicide under the conditions of artifical or natural rain.
In the test of effect of inhibition to germination of spore of citrus melanose by rain drops containing fungicides, the rate of germination increased quickly in the plots of Dithane, but in the plots of Deran the rate of germination increased slowly.
The mist spray and common spray to residual effect were compared, mist spray that is lower dilution, showed the higher inhibition to germination than common spray, even the same active ingredient. This result were seen in both Deran and Difolatan.
The result of inoculation test at the natural rain, Deren and Dithane have shown similar te-ndencies in the case of a little rain. Therefore, rainfall and residual effect seemed to correlate closely. But in the case of a heavy rainfall or rain which falls immediately after spray, the residual effect with Deran and Dithane decreased remarkably, especially in Dithane.