Tree Canker

[Westi]

A bit of advice before I try this treatment plan I found on the Internet.

I have a pear that has a fair amount of canker, no great craters or anything but quite a few patches & fruit affected, except those on new wood. Unfortunately it appears to have spread to my apples as well, so as I can't dig out all trees as they are all mature I went researching.

Obviously I can saw off branches but it also says that on the shallow spots you can cut it out with a sharp knife until you have clean wood & seal it & they recommended Arbrex, which I have bought. The question that is not answered is how the canker travels, does it come in from the bark and when it does, does it just stay there or get into the sap and move around in which case I wouldn't have much success. Anyone else tried this and was it successful? Any more hints & tips?

Thanks in advance!

[Gerry]

Hi Westi,
According to an old gardening book which I have. It seems that Brown Rot spores damage flower stalks and young shoots of apples, pears, peaches, plums, cherries and related ornamental trees. The brown lesions on the wood 0develope into cracks and cankers which may encircle the stems. Later the spores enter the fruitlets through wounds caused by wasps and other insects, hail and frost damage, or severe scab. Regular winter washes will reduce the spores; but cultural control methods are more effective. Cut off all diseased wood and remove cankers. Pick off all dead and rotten fruits.

This is very much like Canker which spreads because fungus spores infect wound edges, laying bare the wood and eventually encircling the whole branch. The disease extends upwards and downwards from the infected area.
Cankers must be treated at the first sign. Cut the diseased area out with a knife, pare the wound clean and paint with a fungicidal wound paint. If a branch is encircled it must be cut back to below the infected area. Badly Cankered trees must be destroyed.

This is all much as you say but it does clarify the way it spreads. I'd go ahead and do the pairing if I was you.

Regards, Gerry.

[Westi]

Thanks Gerry!

I will start with the Apples as they only have limited damage & both are well tasty (a russet & a red eater). The pear has no encircling bits yet, but more affected! I've bought the product so best not waste it! Time to purchase a proper knife though to cut back the bark! Dear Santa....

[Geoff]

I have problems with canker and try to keep it under control by pruning. The reference books I have agree with what you have found. They do emphasise soil conditions, it is the high rainfall here that gives me the problem I think.
Fruit Cultivation for Amateurs - 1951:
"A disease largely influenced by soil conditions. The fungus may also get into the tree through cracks made by scab and good scab control often eliminates canker as well". It talks about cutting away as you have described. "Strong growing, high nitrogen, sappy trees are more liable to canker than trees low in nitrogen. Grassing down and withholding nitrogen but supplying liberal potash can help, as does improving drainage"
The fruit Garden Displayed - 1951 (1974 edition):
Pruning as previously. (I haven't found a mention but if you are pruning rather than just cleaning up be sure to cut back until there is not a brown core to the branch). Also mentions copper sprays, all withdrawn I think. If you are not averse to spraying there may be a legal fungicide that helps if you research.

[Westi]

Thanks Geoff,

I have sandy soil so drainage is not an issue. I think mine started as scab actually so that bit is probably correct. I was wondering to do with the winter fire ash so will give the trees the ash from that this year & with my 'detox' of the canker will wait & see the success! Fingers crossed anyway!