陕北榆树大量死亡原因探析

根据分离培养和接种试验结果，认为白榆死亡是由白榆干枯病感染流行造成，病原菌为茎点霉菌。其发展蔓延具有明显的流域特征：河谷台地、沟坝地、山坡基部发病较重；山顶、梁峁地和山坡中、上部发病轻。红足壮异蝽的危害能加重病害的流行和扩展。

The Reasons for the Death of Ulmus Pumila in Northern Shaanxi

This paper considered it cause the death of Ubnus pumlla that Ubnus pum flaw ithered disease had been infected and popular,through the test of separating,culture and inoculating.The germs was Phan a Sacc.,the devebping and sp reading of that had distinct drainage features,degree of disease was more serious at river valley,gully embankment; the lower part of hillside field than that at the top of a mountain,ridge,the upper and middle part of hillside field.When Urochela quad rlrcotata Reuter harms Ubnus pumlla,the spread of disease will take a turn for the worse.