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Jun 12, 2019 10:31 AM CST
Name: Arturo Tarak
Bariloche,Rio Negro, Argentina (Zone 8a)
Dahlias Irises Plant Lover: Loves 'em all! Roses
Of all diseases canker is foremost the most ellusive.... Confused . It may become widespread for short periods and it takes its toll, but in most of cases it goes by slightly unnoticed until one sees it on a bush that was quite healthy and then going downhill...steeply. Partly because it is a stem disease and partly because it may have different causes: Bacterial or fungal. Does it matter? well as things stand out now not much. It is the plant equivalent of gangrene and parts have to go...mutilation... Sad It may be the outcome of a very poor winter condition. Are the bacteria or fungi simply opportunistic taking advantage of a weakened bush? Or they are aggresive opportunistic using a scar produced by pruning getting into the plant tissues. They may be both... Confused Imho, this simply shows the state of the art when it focuses down to plant immunity to diseases. I can venture that it is just not understood. We've come a long way since Pasteur times with animals ( us humans included), but the plant world is different and plant therapeutics is still a toddler in arms. Most available chems are directly toxic to us,pets or the environment; so prevention seems the only strategy . So giving plants a lot of early care trying to build up vigor for the first 5 (?) years seems sensible. I've seen canker on both bareroot roses ( less) and grafted ( mine all on R.multiflora). Have I've been able to overcome it? Yes in some cases when I decided to lift and pot my declining bushes making sure that they get as much detailed care as possible in my conditions. Last season I lifted all in all 27 bushes that needed extra care. All had had some degree of canker in the previous growing seasons. Of these I finally lost 3, 8 are still recovering ( second year of inside TLC) and 14 have regained vigor and belong to the group that will be placed in ground during these coming weeks. This season I detected about 11 that are/will be lifted. Of these two are own root climbers already inside ( Mme Plantier and Cl.Souvenir de la Malmaison) , the rest are grafted: one is a species rose R.roxburghii plena, one a climber tea (Safrano) , four are D.Austins (Gertrude Jekyll, Charlotte, Graham Thomas, Swan) the rest HT's and Flbs: Whisky Mac, Louisa Stone, Matterhorn. I guess this description just is a proof of how much I was able to improve my rose growing this past season since I reduced to less than a half those that visibly need extra care... Smiling My purpose in sharing this here at the RF is that in my view there seems little direct remedy but alternatively good management practises seems to reduce the risk of this ever present threat. For the time being, it would seem that one has to accept a certain toll on newly settling bushes. The choice of sturdy vigorous initial bushes is a definiteve first step. As it happens frequently bargains don't necessarily end up being so... Rolling my eyes. Whistling
Arturo
Last edited by hampartsum Jun 12, 2019 12:16 PM Icon for preview

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