Abstract:
Malus sylvestris cv.
R 12740–7A and cv.
Spy 227 exhibited conspicuous symptoms, when new Finnish apple cultivars were tested for viruses.
The virus was isolated from the petals of apple trees.
Symptoms in Chenopodium quinoa verified that the virus was apple chlorotic leaf spot virus (CLSV) and the ISEM study confirmed the result.
Purification of CLSV was successful only if the pH of the buffer was raised to pH 9.0. The antiserum raised in a rabbit was reasonable to detect CLSV reliably in the petals of apple trees using the direct ELISA method.
During the summer of 1987, 320 apple trees from eight commercial farms were investigated.
Ten flower samples from different branches of each tree were tested.
The following four cultivars were tested: Lobo, Melba, Raike and White Transparent.
According to the results, CLSV is very common in Finnish orchards, more than 90 % being infected.
Differences in virus concentrations between the cultivars were apparent.
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