柑桔慢衰线虫病在四川的发生危害研究

 对四川省36个柑桔产区324个柑桔园的调查结果表明,柑桔慢衰线虫病 (Tylenchulus semipenetrans)在四川普遍发生,病情趋势是川东部盆地区发生最重,盆周低、中山区次之,川西南干热河谷较轻.果园平均发病率为87.4%,病情Ι级园占35.6%,Ⅱ级占24.6%,Ⅲ级占20.4%,Ⅳ级占6.7%.每年引起的经济损失达2.3%～45%;对18种柑桔品种田间发病情况调查结果:酒饼勒未见发病,香橼、江南柑、曼桔发病较轻,枳对该病抗性表现不一致,其余均严重感病,香橼、江南柑、曼桔发病较轻,枳对该病抗性表现不一致,其余均严重感病;T.semipenetrans田间群体密度周年消长规律研究结果,土中侵染幼虫群体密度以春、秋季最大,夏季最小;根上侵染幼虫群体密度以8月最小,秋、冬最大;而雌成虫全年在根上的发生量均低,而且变动幅度不大.

Occurrence and Damage of Tylenchulus semipenetrans on Citrus in Sichuan,China

After investigated on 324 citrus orchards in 36 districts,the results showed citrus nematode, Tylenchulus semipenetrans occurred in Sichuan at a large scale,with the greatest degree in eastern basin area, a middle degree in low mid mountainous area around the red basin and a smaller degree in southwest dry hot valley area.The average of disease occurrence rate in orchard was 87.4%,the orchards with 1^st patho grade accounting for 35.6%,the ones with 2^nd patho grade 24.6%,the ones with 3^rd patho grade 20.4% and the ones with 4^th patho grade 6.7%.The annual economical lose caused by the disease reached a 23%～45% level.As far as the host varieties were comcerned,Jiubingle was disease free, Citrus medica,mandarin cv.Jiangnangan and Manju had a slighter disease occurrence rate, Poncirus trifoliata had a unstable disease resistance,the other kinds of citrus plants had a severe sensitivity to the disease.In term of the annual variation tendency of populatons of Tylenchulus semipenetrans,in soil the populations density of infective larvae was the greatest in spring and autumn,the smallest in summer,and on roots the populations density of infective larvae was the smallest in August,the greatest in autumn and winter,while the female nematodes infected roots were at a very low degree all the year,with a small variation.