It seems I may have perennial canker in my trees . I've had two suggestions so far . the one way to handle this is cut everything out , (some trees will loose quite a bit of wood ) the other to cut out everything feasible , scrape back the dead bark and paint the area with a 50:50 mixture of boiled linseed oil and either ferbam or ziram . ( this from an old production guide I've managed to dig up ) Does any one have any experience with this ?? David

I have read from a few sources that removing the infected limb(s) is best and rinse all tools in a bleach bath after to prevent spread. However, I have also heard of peach trees recovering, or at least working aorund, the infected portions without any intervention. I have a few plum trees (possibly santa rosa) that have bacterial canker and I am also wondering what can be done so as to not remove the branch that is otherwise, seemingly, healthy (and full of fruit buds!). Most of my infections seem to be at the base of a limb.

I have about 180 trees and have struggled with all the challenges others on this list have. But I was not attuned to look for signs of Nectria canker until I was looking up something else and a picture of canker "clicked" - I had this! (At least I think it is Nectria, although it could have been Anthracnose canker (Perzicula). And I had it bad! But what is (I think) significant is that it was only in the two trees of Williams Pride. My question: is this a recognised phenomenon ? Are some cultivars susceptible, and others not? Of all the trees I have, I would have anticipated that Williams Pride would be least susceptibe to fungal diseases, given its scab resistance, (both scab and caker being fungi...) (Williams Pride, for those who are not familiar with it, is well worth getting to know. It is a product of the Purdue breeding program and is almost totally scab free. Unlike most scab-free cultivars, it is a very good apple with a strong apple flavour. (My personal opinion of most scab-free cultivars, particularly the entire Nova series out of the Kentville station in my home province of Nova Scotia, is that they are on a par with a Red Delicious.) I have dealt with my canker by amputating one tree back to a stub a foot above the graft union, and the other by major surgery, with removal of most of the scaffolds, hacking great chunks out of the remaining wood, and then painting all wounds with copper sulphate "dissolved" in linseed oil. (The book said to dissolve it - it doesn't dissolve in oil. One ends up with a sort of slurry of copper sulphate.) The amputated one has responded with a most gratifying flush of new wood, up to 3 ft. long in one season. (The trunk where I amputated is about 2 inches.)

Fungus induced cankers generally do not have a preferred varietal host, technically. That said, some cultivars wind up encouraging infection due to physical attributes (like vigor and crotch angle) that necessitate more pruning wounds, breakage, etc. Fireblight, however is a bacterial infection and apparently is worse in some varieties. Often there is a correlation of the disease with vigorous ones. It should be noted that "canker" is really a condition, not a disease in itself. The causative agent is a bacterium or fungus, the canker is the result. David, a way you can tell if it is anthracnose is to scrape and look for striation in the inner bark (the characteristic "fiddle-string" sign). Frog eye canker (botryosphaeria obtusa) will display a purple, then frog-eye pattern on the foliage. Diagnosing the specific interloper may be academic, since the treatment is the same. The preceding posts are the right course for most folks, but I would stress the most important is the cutting out and removing of the canker. I use a cabinet scraper for finishing up, to get a smooth surface less penetrable to the pests. Disinfectants, like the aformentioned chlorine solution will certainly help eliminate bacterial or fungal remains, but the wound will soon be susceptible to reinfection. Make sure it is well diluted as bleach solutions will damage live tissue, as will any tar based coatings. Any open wound of course is open game, whether it be a carved out canker or pruning cut. If we are to paint the wounds with fungicides like copper paints we may as well coat all pruning cuts with it. If, however the wound cannot be fully scooped out, a heavy hitter like copper or other preparations may buy some time. In studies of canker treatment, the greatest effect came from a proper scraping, which allowed for a recallousing of the wound site. The late Ken Parr, a local orcharding hero here in the Northeast kingdom (who had his "hands in it into his mid 90's) showed me how he used to continually cut into the callousing tissue to enhance healing a large wound. Cankers can be reduced by constant fungicide spraying, including fall sprays in some areas, as many of the diseases can enter through leaf scars and even the smallest pruning cuts. Another option is to enhance the wound healing with hormones. There have been tests that have shown an increase in healing time with application of natural and synthetic hormones. Perhaps an application of cytokenin containing substances like seaweed, humic acid or willow bark mixtures may prove effective. As is the case with most diseases, canker producing diseases often appear worst in areas of high moisture and even acid soils. Opening canopies, allowing for good air drainage by removing unneeded vegetation in the orchard, and routine ashing or liming may aid in its suppression.

That's a great overview of "canker medicine", mon! I'm glad you brought in notions of herbal options with willow bark... though I'm not familiar with hormone-induced wound healing in this regard. (The salicylic acid content of a willow twig tea possibly plays a role in the plant disease-resistance pathway.) I have used calendula salve on cankers specifically because of that herb's antifungal qualities. Raw garlic minced into small pieces and rubbed along the canker edges in fall may have value as well. The big debate centers on how far one goes in "sterilizing" a wound before treatment. Pruning away the damage completely is best but that doesn't work when that ugly canker situates itself down low on the trunk or a beloved scaffold branch. More than anything else we need to introduce biology as the ultimate option. Here I refer to a competitive environment of microorganisms so that canker-causing fungi and bacteria don't find room at the inn, so to speak. Biodynamic tree paste is the means by which to do this. Tree paste at its most basic is a 50/50 mix of fresh cow manure and local clay. (Those who want more nuance, please start a separate tree paste posting, okay?) The organisms in the manure are allies extraordinaire against canker. The paste can be applied as a wet slurry in early spring and renewed post-harvest. A committed biodynamic grower does every trunk and the major branch structure on an annual basis, usually in early spring, either by means of a paint brush or a dedicated sprayer. I have only gone so far as to treat obvious cankers. The notion of using clay as a “skin rejuvenator” seems apt for renewing bark tissue in the broader sense of tree health.

This is for anyone out there growing Sweet Sixteen apple. I have noticed recently appears to be canker, kind of, on trunks and large branches of these guys. Characteristics are an almost natural looking peeling of the bark, with some patches showing a slight fiddle-stringing. It doesn't look anything like anthracnose, however, which tends to be localized and has severe fiddle-string striations. It doesn't look like any of the other canker diseases I have researched so far, and I have never seen fireblight strikes in these areas. This cultivar is also touted as fireblight resistant. The wierd thing is I see it only on the Sweet Sixteen's (I have hundreds of varieties out there), and it is on all of them- about a dozen trees, many isolated around the property. It really doesn't appear a natural affectation. Does anyone have a similar story?

Could someone clarify this for me, please. I'd like to use biodynamic tree paste on a few cankers in our orchard, but should I carve away the canker, then apply or just spread it right on the canker? And, when pruning a tree with a canker, is the fungus present on other limbs or just the area where the canker is?

Any chance of a picture , Todd ? On 13-Mar-10, at 3:56 AM, Todd Parlo wrote in http://grou.ps/groworganicapples/talks/1466566 This is for anyone out there growing Sweet Sixteen apple. I have noticed recently what appears to be canker, kind of, on trunks and large branches of these guys. Characteristics are an almost natural looking peeling of the bark, with some patches showing a slight fiddle-stringing. It doesn't look anything like anthracnose, however, which tends to be localized and has severe fiddle-string striations. It doesn't look like any of the other canker diseases I have researched so far, and I have never seen fireblight strikes in these areas. This cultivar is also touted as fireblight resistant. The wierd thing is I see it only on the Sweet Sixteen's (I have hundreds of varieties out there), and it is on all of them - about a dozen trees, many isolated around the property. It really doesn't appear a natural affectation. Does anyone have a similar story?

Perennial canker is caused by a fungi that reinfects healing callus over and over again each fall. Cutting out "the center" of a canker before slathering with tree paste wouldn't have any relevance as the action is on the edges. Canker disease is basically an opprtunistic organism that zeroes in on unhelaed wounds, often a pruning cut. It's not so much hiding out on the bark surface in a definite way as simply in the environs. It srikes because unhealthy tissue is available. Thus tissue health is really the critical factor... clay/ manure actually works on an even deeper level than merely one group of organisms outcompeting another. Slather away, CJ!

Much of what looks to be canker is from pruning where the tops of the branches are exposed to the most sun. I tried a pruning technique for semi-dwarf trees described in "Ecological Fruit Production in the North" where most of the fruiting wood hangs downward. The technique should be modified for northern Missouri. Jonathan's are especially bad for what looks to be canker, or sunscald. I'll try some pictures later.