| Abstract: | Of twenty non-ionic surfactant formulations tested in 1974–75 several were successful as eradicants of overwintering apple mildew as were two ionic materials. The incidence of Nectria canker was increased by sprays applied in October but less so by the same materials applied in January or February when phytoxicity measured in terms of fruit yield was also less. PP 222, a non-ionic surfactant introduced in 1975, proved to be an efficient eradicant of mildew in 1976. Although the yield of fruit from most sprayed trees was greater than from controls, the best mildew eradicants did not produce greatest yields in the same year, perhaps indicating adverse effects of treatments on the trees. However, significantly better yields of fruit obtained in the year following the dormant season eradication of primary mildew, suggest long term beneficial effects of these treatments. |
