Saturday, 5 January 2008

More on Canna virus

Canna Trials were held in 2002 at the Royal Horticulture Society. The trials were the first occasion that the prevalence of Canna virus was made known to the general public.

Published in Proceedings of The Royal Horticultural Society for that year, is an interesting Canna reference. It states that at a committee meeting held on the 19th November 2002, a committee member stated that the canna virus was less apparent during September and it seemed to be more prevalent where the soil was poor.

This confirms our own experiences at Claines Canna, and it provides us with several possibilities.

The first possibility is that many Canna cultivars suffer stress in northern latitudes, and this results in foliage markings that are the same visually as the effects of various viruses. We saw evidence of this during this last summer, when we had record rain and flooding, and also saw very little direct sun-light. Cultivars that I am convinced are virus-free produced foliage that could easily be confused with virus contaminated foliage. The vocabulary of Canna is very limited, and this is not surprising.

Secondly, there is a viewpoint advocated that much of the worlds Canna is contaminated, but good growing conditions can conceal its presence. That theory could also be confirmed by our own summer experiences if we accepted that hypothesis.

It seemed at one time this year that horticultural authorities were prepared to spend money on research at the UK Science Laboratory, but news from that quarter has become scarce. Therefore, it looks like we will face 2008 in the same sorry state of ignorance, with each of us just doing the best we can.

2002 Proceedings of The Royal Horticultural Society

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