How wide spread in the PNW is canna yellow mottle badnavirus (CYMB) and bean yellow mosaic virus? I know on the global scene it's a problem, but I see a lot of healthy cannas around here, none virused.
canna yellow mottle [CaYMV] is extremely widespread but often present asymptomatically. BYMV is fairly common in cannas too but much less so than CaYMV.
I've wondered the same because I'd never seen it. I'm having my doubts now after aquiring (what was sold as) 'Black Knight'. I recall having 'Black Knight' in the past but not the coloring in the leaves I'm seeing here. There seems to be a yellow mottling which I'm not sure belongs there normally. I know there isn't a mite problem which can have a similar look. So two questions exist, is this the Canna virus and is this 'Black Knight' (in flower currently)? Cheers, LPN.
on #1 - tough to say without actual ELISA or PCR testing. #2- the leaves certainly look different from what horn nursery sells as 'black knight' :
LPN, you might be interested in this- a newly discovered canna potyvirus called Canna Yellow Streak Virus. from claine's canna: Tuesday, 12 June 2007 Another Canna virus discovered Samples of Canna plants coming into the Central Science Laboratory's (CSL's) plant clinic have been found to carry a new virus - Canna yellow streak virus (CaYSV), so reports The Commercial Greenhouse Grower in its June 2007 edition. Dr Rick Mumford, the senior virologist at CSL, said "Typical virus symptoms include flecking, mosaic, leaf streaking and necrosis, which in severe cases renders plants unsaleable. With individual Canna specimens retailing for 15-20 pounds, the losses for commercial growers can be large." Until CaYSV was found, four different viruses have been reported to infect Cannas, with Canna yellow mottle virus traditionally considered the most important. Rick Mumford explained: "We are still trying to establish how widespread this new virus is, but preliminary findings show it is consistently found in plants showing severe virus symptoms and hence is likely to be an important cause of virus disease in Canna." My first feeling was one of despair, yet another virus! But, in fact, this is good news. At last scientists are starting to find out what is wrong. The virus has obviously been there, unrecognised, for many years, now at last it is identified. This also explains why plants that had been cleared of virus in laboratory testing, were subsequently found to exhibit the symptoms described by Doctor Mumford. We are one step nearer to being able to establish which are clean specimens and which are carrying virus, and corrective action in the form of segregation and culling then becomes a fully practical possibility. Incidentally, Dr Mumford mentioned 5 separate viruses. The RHS laboratories at Wisley identified three viruses after the 2002 Canna Trials (CYMV, BYMV and Tomato aspermy virus), and I seem to have missed the identification of another one in the interim. http://www.clainescanna.co.uk/CannaNews/CannaNews.html
