Canker, techniques and organic treatments to avoid it
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Infecting most ornamental plants such as cypress, willow or fruit trees such as the peach tree, apricot tree or cherry tree, canker is a fungal disease that attacks the branches and even trunk of the tree.
Very quickly, branches seem to waste off.
They dry up, die off and often sticky gum flows out of wounds.
Conditions leading to appearance of canker
Inside an infected branch, the tissue is dead
This fungus particularly loves moisture. It will tend to spread when the weather is hotter than usual and moisture due to previous rains is still present.
Whenever the tree is wounded, ensure the wound is as clean as can be. If a saw was used, remove the frayed, jagged line at the bark cut with a sharp knife or billhook. It’s like whittling away the frayed ends to make the cut smooth. If not, healing takes longer and canker will more readily appear.
How to fight against canker
Preventive care – spraying Bordeaux mixture helps to effectively reduce risks.
Start applying this in September. Renew it three times for a month and a half (every two weeks).
In spring, spray once or twice starting in March, again with a fortnight between sprayings.
Curative care – remove canker-infected branches immediately and burn them.
If the trunk itself is hit, remove as much of the contaminated surface as you can. Use billhook or sharp plane that you disinfect repeatedly, until reaching the healthy portion of the bark.
Preventing and curing canker: which measure, and when
Canker is fought on two fronts: keeping the fungus from taking hold, and cutting out the wood it has already killed. The table sums up what the article recommends, and the moment for each measure.
Preventing and curing canker: which measure, and when
Approach
What to do
When
Preventive spraying (autumn)
Spray Bordeaux mixture, renewed three times every two weeks
From early autumn, over a month and a half
Preventive spraying (spring)
One or two sprays of Bordeaux mixture, a fortnight apart
From early spring
Wound care
Smooth frayed saw cuts with a sharp knife or billhook
Whenever the tree is wounded or pruned
Curative work on the trunk
Pare away the contaminated surface with a billhook or sharp plane, disinfected repeatedly
As soon as the trunk is found to be hit
Curative pruning
Remove infected branches and burn them
Immediately, as soon as symptoms show
Prevention spares the tree; once wood is dead, only removal and burning stop the spread.
Written by Gaspard Lorthiois | Loves helping out, especially when it comes to growing things. Worked in herbal medicine, runs a farm, and dabbles in tech. Master's degree and engineer.
