| dc.description.abstract |
A previously undescribed virus disease of lettuce, for which the name lettuce necrotic yellows is proposed, occurs in epiphytotic proportions in Victoria and, to a similar or lesser extent, in parts of Queensland, New South Wales, and South Australia. Infected plants are extremely chlorotic and have a flattened appearance. They exhibit varying degrees of flaccidity and necrosis, and the mortality rate may be high. Chronically affected survivors have small, slightly distorted, but otherwise normal heart leaves. The tomato spotted wilt virus, which causes an almost identical disease in lettuce, lacks the 'recovery' phase. The virus was sap-transmissible from infected lettuce or sowthistle (Sonchus oleraceus L.) to several indicator species, but not to lettuce or sowthistle. Lettuce has been infected on a few occasions with inoculum from Nicotiana glutinosa L. There is no evidence that the virus is transmitted through lettuce or sowthistle seed. The virus was inactivated in N. glutinosa sap between 52 and 54 |
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