A preliminary SDV survey was initiated in the spring of 1993, on satsuma orchards in the Kerikeri district. It is therefore necessary to pass the suspected SDV extracts through a CTV resistant plant prior to indexing. This step of the indexing procedure will be completed in September 1995 and biological indexing results for SDV will be completed in June 1996. Citrus Psorosis Complex Citrus psorosis is a disease of citrus commonly known as scaly bark. It causes a loss of vigour which is accompanied by reduced fruit quality and dramatic reduction in yield.
Severe infections can result in the death of scaffold branches and occasionally the entire tree.
Psorosis is now believed to be a complex of diseases with each component being caused by a different virus, each differing widely in its effect on the trees. The shock symptoms are characterised by the sudden death of young shoots. Figure 7 Psorosis shock symptoms on nursery plant. Electron microscope observations of these particles suggest that these trees were infected with the citrus ringspot virus, a component of the psorosis complex. The majority of citrus species are symptomless carriers of this disease complex.