【摘要】 广东桑树萎缩病的症状与江浙黄化型桑树萎缩病基本相同。主要发病地区为顺德、南海、中山、新会和鹤山等县,发病率一般在10%以下,严重的达50—80%。病株减产达70%,用病叶饲蚕所生产的丝茧缺乏光泽,茧形不整。各种嫁接传病试验结果说明:(1)本病可借嫁接传染,进一步说明本病和江浙黄化型桑树萎缩病可能完全相同;(2)发病初期及中期的枝条,不是每一个芽都含有病毒;(3)病树的根,只部分含有病毒。用桑树上常见的两种浮尘子(其中一种为 Erythroneura mori Matsumura)及一种粉虱(Bemisia myricae Kuwama)分别进行传病试验,未获成功。种籽传病试验结果:病株种籽所长出的2684株桑苗全部没有发病,初步说明种籽传病的可能性不大。更多还原

【Abstract】 The symptoms of mulberry dwarf in Kwangtung are similar to those reported from EastChina.The rate of the disease incidence in most places is generally below 10%,but in somelocalities may be as high as 50-80%.The yield of leaves of infected plants in weight wasestimated to be about 30% of that of healthy plants.The shape and size of the cocoons pro-duced by the silkworms feeding on infected leaves are not uniform,and the luster is inferior.The results of transmission tests by grafting show:(1) that the disease is graft-trans-missible,confirming the virus nature of the disease and further suggesting its identity withthe mulberry dwarf in East China;(2) that not all the buds (including the portions of woodto which the buds were attached) of the infected twigs are infected with the virus in Springand even in Summer;(3) that the virus is present in only some of the roots and even only ina portion of a root,and that the small lateral roots (smaller than 2.2 mm in diameter) areall completely free from the virus.Two kinds of leaf-hoppers (one of which is Erythroneura mori Matsumura) and mulberrywhite-fly (Bemisia myricae Kuwama) so far tested fail to transmit the disease.All of the 2684 seedlings grown from seeds Collected from infected mulberry treesappeared to be healthy up to six months old.It is thus unlikely that the disease is seed trans-missible.更多还原