Considering New Zealand’s small size and remoteness, a remarkable number of plant pathogens have been recorded. A complete review of the records of plant viruses, viroids and mollicutes in New Zealand found good documentary evidence for 186 viral diseases, 5 viroids and 6 mollicutes, of which 59 viruses, 3 viroids, and 4 mollicutes have been recorded since publication of the previous complete review in 1989. Based on a lack of sufficient documented evidence, a further 27 viruses, 5 viroid and 3 mollicute records were considered unconfirmed. The confirmed pathogens not only infect agricultural and horticultural crops but some also affect the native flora.

The cytokinin content in the primary leaves of bean (Phaseolus vulgaris) was monitored for 10 d after inoculation with white clover mosaic potexvirus. The cytokinins were isolated, purified, separated by high-performance liquid chromatography, and quantified by radioimmunoassay. The cytokinins detected at the time of inoculation (d 0) were: (a) the free bases, zeatin (Z), dihydrozeatin (DZ), and isopentenyladenine; (b) the riboside, DZ riboside (DZR); (c) theO-glucosides of DZ, DZR, and Z riboside; (d) the nucleotides, Z riboside-5′-monophosphate and isopentenyladenosine-5′-monophosphate; and (e) trace amounts of Z-9-glucoside and DZ-9-glucoside. During the 10 d after inoculation with white clover mosaic potexvirus, marked quantitative changes in this cytokinin profile were observed. The concentration of the free bases and DZR decreased, accompanied by an increase in the 9-glucosides and the nucleotides. Virus titer increased rapidly 3 d after inoculation, attaining a maximum level at d 5. This increase coincided with the increases in the 9-glucosides and the nucleotides. We propose that the decline in the cytokinin free bases and riboside may allow the increase of virus titer in bean and lead to the senescence of infected leaves.