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一、问题的提出电白县海岸线长81公里,宜林沙土5万亩。在木麻黄海岸防护林建设中,过去曾负盛名。但是随着时间的推移,更新造林次数的增加,林分生产率不断降低,尤其是木麻黄青枯病日趋严重.在7,8年生的林分中,木麻黄青枯病发病率由造林初期的0.01％发展到第二次更新造林的13—26％;特别是在1972—1975年连续4次11级以上强台风袭击后,导致青枯病的全面蔓延,数万亩木麻黄林一片黄暗,失去葱绿喜人、生气盎然的景象,大量林木感病死亡,造成大面积的疏残林。目前病害还在蔓延中,近年更新造林的7、8年生林分,青枯病发病率在50—60％,严重的达90％,给林带的更新恢复工作带来了极大困难。同时,单一木麻黄的长期种植,土壤中某
First, the issue put forward Dianbai County coastline 81 kilometers, 50000 acres of sandy soil. In the Casuarina coast shelterbelt construction, the past has been prestigious. However, with the increase of afforestation times, the stand productivity decreased continuously, especially the Casuarina equisetifolia .In the 7-8 year-old stand, the incidence of the yellow pathotype was changed from the early afforestation 0.01% to 13-26% of the second reforestation; especially after four consecutive typhoon attacks of magnitude 11 or above between 1972 and 1975, which led to the full spread of bacterial wilt. Thousands of mu of casuarina forest were yellow and dark , Lost vigorous green, vibrant scene, a large number of forest disease deaths, resulting in a large area of sparse forest. At present, the diseases are still spreading. In recent years, the annual afforestation of the 7-8 year old stands has the incidence of bacterial wilt in 50-60% and seriousness of 90%, which brings great difficulties to the renewal and restoration work of the forest belt. At the same time, long-term cultivation of single Casuarina in the soil of a