柑桔毒素病之研究－Ⅰ.外觀健全與罹病柑桔植株在墨西哥雷木及檸檬反應之異同

Abstract

採自外觀健全與罹病柑桔植株之接穗，經嫁接於墨西哥雷木上，均可產生Tristeza典型病徵，偶爾可在較老葉片上出現木栓化病徵。檸檬上產生葉片黃化、落葉、葉片狹小及節間縮短等病徵，顯示Trioteza毒素病原已普週存在於臺灣柑桔園中。 The purpose of this study is to realize the similarities and differences of reactions the healthy-appearance and diseased-appearance of citrus trees on Mexican lime and lemon. Preliminary results found that both apparently healthy scion and diseased scion grafted on Mexican lime exhibited the symptoms of tristeza disease, such as veinclearing, water-soaking, stem-pitting and smaller leaves on lime.Under this study It is not unusual vein-corking was found in older leaves. When these two different scions were grafted on lemon, the symptoms of seedling yellows were shown after 2-3 months. Therefore, it could be sure that tristeza virus exhibits in both healthy-appearance citrus trees and diseased-appearance citrus trees in Taiwan. It was also found that most newly developing leaves from diseased scions is different from that of apparently healthy scions. In advanced observations, these newly developing leaves of the former showed the symptoms resembling the deficiency of iron or manganese element after 3-4 months. It alse showed severe yellowing, stunting and smaller leaves. The symptoms of micro-element deficiency were more clearly when the diseased scions were grafted noto Valencia species. The dieased plant that called Huanglungpin may suggest the presence of another agent, probably greening disease, in addition to seedling yellows-tristeza.