Articles
VIRUS INCIDENCE AND SPREAD IN AUSTRALIAN TRIPLOID HOPS (HUMULUS LUPULUS L.)
In 1996, incidence levels of hop latent virus (HLV), HMV and PNRSV were 64.7%, 60.0% and 66.0% respectively.
Analysis for the 1996 infection data showed there were significantly more co-infections of HLV and HMV; P < 0.05) than would have been expected by random occurrence.
This was independent of PNRSV infection.
The rate of spread of PNRSV in this cultivar was much more rapid than shown previously in other Australian hop cultivars and in many similar studies overseas.
In a further survey in 1996, more than 700 plants of four cultivars were tested by DAS-ELISA for the three viruses.
Three of the cultivars, including ‘Victoria’ were propagated from virus-tested planting material, and the fourth from PNRSV infected material.
All plants were established in 1989 in a replicated cultivar x row spacing trial with differing distances between plants within blocks.
Significant differences (P < 0.05) in levels of HLV, PNRSV and total virus infection were found between cultivars, but there were no significant differences in the incidence of HMV between cultivars nor any significant effects of the differing row spacings on incidence of any of the viruses (P < 0.05). The incidence of PNRSV in ‘Victoria’ was significantly greater than in the other cultivars tested that were propagated from virus-tested planting stock.
The apparent variation in virus resistance between these genetically related hop cultivars has important implications for hop breeding programmes.