My impression with most trunk strikes is they come through vulnerable spots in the trunk itself, they don’t travel down from the blooms. It can also come in from small waterspouts by the base, you need to remove all those with a vengeance as that is the easiest way to lose a whole tree.
When I get a canker on a big scaffold if it did not girdle and kill the branch I keep the whole thing. I may scrape it off / blowtorch it / paint it / do nothing depending on how oozing it looks and how bad FB is currently.
Very helpful, thank you!. Supports the idea that cankers or trunk strikes do not by themselves mean that the wood above them is infected and needs removal. Knowing this is really critical.
Let the surgery begin. Pawpaws, persimmons, figs, looking better every day.
This is from a university guideline I provide the link for below- “Initially the disease often enters the tree through natural openings, especially flowers and wounds in the spring. Once established in the tree, fireblight quickly invades through the current season’s growth into older growth.”
Funny, but that’s a bit of a contradiction- when it enters through wounds it would seem to be entering older growth directly.
Doesn’t this mean you would be safer waiting for a dry spell in summer to do all pruning of infected or highly vulnerable trees, beyond just cutting back strikes and cankers? Do the warmer temps of summer discourage the spread of FB regardless of precip? From another university guideline
“Temperatures** between 75 and 82 F and humidity above 60 percent allow the bacteria to reproduce and **spread”.
Why not wait for temps above 85? Summer pruning also reduces the vegetative response.
My understanding is you cannot spread blight in winter or above 90 degrees in summer. I cut out cankers and blight strikes in winter (that I missed in summer) and in summer whenever I see them, always leaving a 4 to 6 inch Ugly Stub in at least two year old wood (per Prof. Steiner.) to be removed the next winter with a flush cut.
Using a Blowtorch to Kill Fire Blight Canker (source WSU):
“Some growers have effectively used blowtorches to kill cankers that were difficult to remove from the tree. As the bacteria are killed at about 150-160 degrees F, charring the wood to kill the canker is not necessary.”
I’m not arguing with you… I have no experience with FB yet and am trying to learn.
I was under the impression that FB can be spread through unsanitary pruning practices when temps are below freezing, but the infection would not become active until temperatures warmed/spring arrives. The idea being that the bacteria us still there, even if it isn’t active.
@LTCider That’s a good question! Penn State says * Disinfecting pruning tools is ineffective for minimizing spread of the disease since the bacteria often are present internally in mature bark well in advance of symptom margins."
Dr Kari Peter Penn State " * Bacteria can invade healthy tissue up to ~3 feet in advance of visible symptoms, which makes tool sterilization not effective."
My guess at an answer to your question: blight will end up on that pruning cut no matter what you do. In spring/summer blight is everywhere- in the air, on every square inch of bark-and will find that pruning cut even if your pruners were sterile in winter. I emailed Steve Wood at Poverty Lane Orchards to get his take. He’s a big proponent of Paul Steiner’s methods, has battled terrible blight for decades.
I had my blowtorch in the orchard this weekend. I was looking for any FB and bacterial canker spot, all I found was cankers on cherries to hit. I have been having a problem with an uptick in bacterial canker recently, a large wild cherry got it and seems to be spreading. I need to get it taken out I expect but I tried blasting it.
I don’t think it hurts to torch pretty hard as some of it may have gone further into the wood (this is based on cutting up and looking at dead trees). Just make sure it is not so hot as to girdle the whole limb. I also hit all around the canker for the same reason, it may have traveled further than you can see.
As an extra added bonus, the more you torch the better it feels… “die disease, die!!”
I had fire blight on the central leader of a wolf river apple which I thought was fairly resistant to the same. After much consideration, I cut the leader well below the blight and I’m training a side branch to take its place. Regarding copper, does it treat both fungus and bacteria? I worry about copper and my bees. I was thinking that sulfur would be a better choice.
As @scottfsmith has brought up before though copper might be a good treatment once or twice a year for fireblight its technically a heavy metal. Copper is not meant to replace sulphur as a fungicide. Copper does reduce but not completely inhibit bactetial growth and i find it useful only in early spring pre bloom. Once blooms are open i would not spray with anything until post bloom due to concern for the pollinators.
So a lot of treatments you just need to make sure to not spray on flowers and to spray after the sun goes down when the bees go home. I think there are many safe options for bees and other beneficial insects out there and i would put sulfur and copper correctly used in that. Please keep asking about what you feel is safe and link anything (like the link that said spinosad is bad for bees) you have questions on as all of us like to learn. I would also like to add that Fireblight is not a good bacteria for bees who usually want wild yeast around (and beneficial lactic bacteria) to help them make bee bread. (It also makes sense why @JoeReal vinegar spray works so well) This is a reason why i like to use beneficial bacteria on my fireblight spots and i think this strategy would work better in humid area’s as i need to get lucky and apply it when we have a few days of wet.
What i think is most important for bees is not using herbicides like glyphosate and weednfeed, and pesticides and fungicides that have residual impacts or impart there chemicals into the nectar of plants. The pesticide industry has invaded many beekeeping groups and now recommends you use pesticides on your bees if you even find 1 mite on a board (ten years ago you waited until 80-350). If your bees do get varroa destructor mites you can do the powdered sugar method or you can also buy predator mites who naturally exist with bees in there wild hive colonies.
I feel fire also just stimulates growth in trees as well as disinfecting, if you go to far its just a hard prune right?
Lots of good information in this post, Richard. I had not considered that varroa mite tx could also be considered a pesticide of sorts, but I understand what you are saying.
I am still reading and making decisions about the copper vs sulfur, etc, and what I think will be best for me. I learn something new every day from this site. I could benefit from an abbreviated spray schedule (leaning to organic) so that I can start off right this year. I have used a dormant spray, and want to establish a routine I can follow.
