Detection of apple rubbery wood virus in some Tasmanian varietal selections using Lord Lambourne as an indicator

Abstract

Apple rubbery wood virus was found to be prevalent among varietal selections taken from commercial Tasmanian orchards. Bending and sway tests to detect symptoms of rubbery wood in Lord Lambourne scions in the field were not always reliable, and it was necessary to check field observations by staining cross-sections of wood with phloroglucinol-HC1 and observing them for lignin development. Results are discussed in relation to factors affecting vigour, and variation in the degree of lignification within infected trees. It is concluded that the indexing of each tree on Lord Lambourne should be replicated more than six times, and that three or more sections should be taken from the two-year-old wood of the indicator growths for staining to ensure detection of all infected selections. Although Lord Lambourne is not an ideal indicator for the detection of apple rubbery wood virus under Tasmanian conditions, there does not appear to be a more suitable alternative available.