ISHS Acta Horticulturae 668: I International Humulus Symposium
EPIDEMIOLOGY AND MANAGEMENT OF VIRUSES OF HOP IN AUSTRALIA |
| Author: | S.J. Pethybridge |
| Keywords: | Apple mosaic virus, Hop mosaic virus, Hop latent virus, disease losses. |
| Abstract:
The incidence, means of transmission, and effects of Hop latent virus (HpLV), Hop mosaic virus (HpMV), and Apple mosaic virus (ApMV) (hop, H, and intermediate, I, serotypes) within hop gardens in Australia was studied over several years. Differences in the rates of virus re-infection occurred between cultivars after garden establishment with virus-free material (negative for all 3 viruses by serological testing) were observed. The highest rates of virus re-infection occurred in ‘Victoria’ and ‘Agate’. Slow re-infection rates in ‘Pride of Ringwood’, ‘Opal’, and ‘Super Pride’, suggested traditional management techniques of virus control including garden establishment with virus tested material and rouging of infected plants soon after establishment would be effective. However, the rapid rate of virus re-infection and significant deleterious effects on production (cone yield and levels of brewing organic acids) meant that alternative management options to reduce intra-garden spread would need to be incorporated. Fitting of spatial and spatiotemporal models to viral epidemics suggested local spread of both carlaviruses. However, for HpMV epidemics in ‘Agate’, infections initiated from background (outside the garden) source such as immigrant viruliferous aphids were also apparent. Furthermore, the species of aphids that may contribute to foci initiation within gardens were determined, the numbers of which were influenced by cultivar and location. Significant background contributions to an ApMV epidemic was also suggested in a ‘Victoria’ garden at Bushy Park. In glasshouse trials, the transmission of ApMV was achieved by pruning virus tested plants after virus-infected ones, shoot contact, and root grafting. These mechanisms may contribute to the local (within garden) transmission of ApMV. | |
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