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花叶型退化病在广东普遍而严重发生,但中山、潮汕等地一些农民通过选种(淘汰病株)几十年来把此病压低到10—5％以下。 根据指示植物、寄主范围、传病方式、物理性质和血清反应(只试x病毒)等试验结果,我们鉴定了广东马铃薯花叶型退化病株中最普遍存在的两种病毒为马铃薯病毒x和马铃薯病毒y。 从23个品种940株“健株”和表现不同程度退化的植株中进行分离接种鉴定,结果表明,表现退化的植株绝大多数含“x+y”或y;“健株”绝大多数仅含x不含y,少数既不含x也不含y。其中有7个品种还分离不到x。土温测定结果表明广东中山等地冬种马铃薯的土温基本适合于马铃薯生长,田间黄皿诱蚜结果表明y的传病媒介蚜虫(棉蚜和桃蚜)是存在的。因此,认为在广东本病的流行是由于新侵染所引起。农民选种防病的原理在于每年把带病毒y的种薯所长出的和早期感染病毒y的症状明显的病株和薯块除去,留下没有感染的健株和少数后期感染而症状不明显的病株的薯块作种薯,因而每年都能把病毒控制到10—5％以下。
Mosaic degenerative diseases are widespread and serious in Guangdong, but some peasants in Zhongshan, Chaoshan and other places have reduced this disease to less than 10-5% by selecting seeds (eliminating diseased plants) for decades. According to the test results indicating the plant, the host range, the mode of transmission, the physical properties and the serum reaction (only the test x virus), we identified the two viruses most prevalent in the potato mosaic-type degenerative strains in Guangdong as potato virus x and Potato virus y The results showed that the most degraded plants contained “x + y” or y, and the vast majority of “healthy plants” were only isolated from inoculated plants of 940 “healthy plants” and 23 plants that degenerated to varying degrees. X does not contain y, a few contain neither x nor y. Seven of them are also less than x. The result of soil temperature showed that the soil temperature of winter potato in Zhongshan and other places in Guangdong was suitable for the growth of potatoes. The results showed that the vector aphids (cotton aphid and peach aphid) of y were present. Therefore, we think the prevalence of this disease in Guangdong is caused by new infections. The principle of farmers’ selection and prevention of diseases lies in that the diseased plants and tubers which grow out of the seedlings with virus y and the symptoms that are early infected with virus y are removed each year, leaving untreated healthy plants and a few late-stage infections without symptoms Obvious strains of potato tuber for seed, so every year the virus can be controlled to below 10-5%.