一、前言由紫韧革菌(Stereum purpureum)引起的银叶病,除为害苹果外,杏、梨、桃等果树,紫丁香、白杨、桦木等树木也有发生,在许多国家曾造成重大损失,特别对欧州的李树危害更重。1919年欧州曾颁布过所谓“银叶令”法规,可见其危害的严重性了。在日本除苹果外其他树木未见发病,而且为害苹果也仅限于青森县,其他县发病很少。 I. INTRODUCTION Silver leaf disease caused by Stereum purpureum, in addition to apples, trees such as apricot, pear and peach, lilac, poplar and birch trees have also occurred, causing heavy losses in many countries. Especially for the European plum harming more. In 1919, Europe had promulgated the so-called “silver leaf order” law, showing the seriousness of its harm. In Japan, no disease other than apple trees was found, and the damage to apples was limited to Aomori Prefecture. Few incidences were reported in other counties.