Just wondering if I could get some advice on what looks like a bit of an outbreak of pseudomonas syringae across my maple collection. I'll take some pictures and update tomorrow (it's dark now in the UK), but what was last year a single incident confined to a Bi Ho, which I luckily caught in time and treated (it's slowly recovering), appears now to have hit at least two of my more established maples and a third slightly younger. I've got the elements for Bordeaux mix arriving tomorrow. But would appreciate any steer from those with experience around what might be causing this and any preventative steps I can take to reduce the risk of further trees being impacted. As a side note, all of these Acers were in the ground - which is making me concerned it might in fact be verticillium wilt. But if that was the case, would my Bi Ho have lived for over a year now following a swift amputation to the infected limb and several drenches of copper fungicide? I've also read up about Botrytis. Anyway - thoughts welcome on best way of reducing a future reoccurrences.
Good evening @stg, before we think about verticulum wilt. Let's look more at pseudonomas syringae. Take a look at this link. Diseases Caused by Pseudomonas syringe And re Biho, this is not a maple I would take as a good example of this pathogen. It is a very difficult cultivar at the best of times. Regarding treatment, then the Bordeaux mix is the best route IMO. So you are going down the right route. The one thing I would say is consider leaf collection at the end of Autumn each year. It is one step that can help prevent these problems. It is time consuming, but it does seem to help in my experience. Anyway, let's see what your photos show tomorrow.
Original Bi Ho It’s now pretty much as in the photo going strong. — This tree however: Now looks pretty bad, wood appears to be dead. Awful photo I’m afraid (will update tomorrow): — And the same here: This tree is really bad now, very little live growth from what I can tell. See low down or at the extremities. Most wood appears to be dead. Again better photos tomorrow: -- And a slightly younger tree looks as follows:
Hi again @stg. Verticulum wilt often shows itself in the Summer by wilting of leaves on one side of the tree, whereas the other side seems perfectly healthy. Your red maple does seem to show this pattern. There is no cure for VW. But if you want to save this tree, then remove all the dead wood now and add a precaution, apply Bordeaux mix to the cut ends. This is in case it's pseudonomas syringae. I do think the photos of your last red maple is a lost cause tbh. I can only see a little life on one stem and that one doesn't look too good either. If it were me I would remove both trees and not replant a maple in that area. Verticulum is soil born, so any newly planted Acer would probably succumb. You can place a pot with a maple in that area to give it a fighting chance, but not in that garden soil. Sorry I don't have good news for you.
Here’s some better photos hopefully. Same order as above, 4 different trees. I’ve included the Bi Ho for a sense check on VW — this tree is still alive and in bud. I fear my Jerre Schwartz is just dead. No chance. Could I salvage my Garnet with a radical prune, copper paste and hope for the best? I could remove it, clean the roots and repot in bonsai soil and keep isolated. Super aerated. (Similar to bi ho). The final tree, sango kaku which will follow in another post (image limit) I took a branch off in haste late yesterday when I saw the damage shown. I’m going to copper paste the wound / spray entire tree on a regular basis but should I remove this and isolate? —————————————————————————— 01. Bi Ho 1 year ago - my first issue emerged, tree was sprayed with copper fungicide and a bad limb removed. This photo is just post work complete and an example of a bad smaller branch. That tree appears to be doing okay now, today it looks like this: ————————————————————————— 02. Jerre Schwartz 9 months ago / last season: Today: —————————————————————————— 03. Garnet 9 months ago / last season: Today:
Finally, 04. Sango Kaku. Last season doing fine: And today, a infected branch removed from main tree. Branch: Tree:
I'm sorry to say @stg but IMO that is verticulum wilt. I would do as you suggested and give them a try in a pot after a soil wash and isolate. Might not do any good, but worth a try. Perhaps!! I had one tree that had VW for many years and did OK ishh. But it did die in the end. Just to mention, I did remove 5 barrow loads of the infected soil and did not place another maple in that position. A fir is now in it's place with new top soil. VW can survive for several years in garden soil, so it's best to ere on the side of caution. Just to say; the good thing about potted maples, is that you can replace with a new maple in the same position with clean pots and new quality compost mix. R @dicky5ash does this very successfully in your part of the country.
@Acerholic - thanks for the prompt reply. To clarify, all look like VW? Should I remove other Acers in the garden soil, and treat even without any VW signs to get ahead of it? E.g. repot and clean off of old soil (dispose appropriately) or just wait and chance it. I have removed the 03. Garnets branch and taken some cuts to show internals:
Yes, I think they are. Not so prominent as the other cross section, so could be pseudonomas. If you are up for it, then I would carry out the lifting, root wash and potting up. And yes disposal of the soil to the council dump would be a very good idea. Replace with John innes top soil. I find this very good indeed. Or you can chance it, but in the end they will most likely succumb. It might take several years, so this is a call you have to make.
Thank you for the advice. Would it be wise to wash the roots with hydrogen peroxide for those potentially in infected soil but not currently showing any signs of VW? I’d replace the mycorrhizas upon reporting.
Hi, you've had lots of good advice from Derek, all of which I agree with, but since I looked at the pics I'll give you another view: Bi hoo: good pot and planting length looks OK, though could be lower; Dutch nuderstock often has one or so roots sticking out, with the real root flare further down the stem. (This is because the understock is carelessly replanted very high, in peat, into godets for grafting, where it stays for about 2 years, letting higher lateral roots form). I think it's a good idea to find the true flare and leave the upper roots very exposed. The 4th pic is a classic demonstration of not leaving enough of a stub when you cut back. In trees with weak skins, the infection/dieback from the cut will continue quite far down, as it's done down the side. Leaving a longer stub will allow the tree to comparmentalize better, as I think you see in another pic. This tree should be OK, just keep up with the Bordeaux mix. Jerre Schwarz: appreciate the daylight pics, I find it very hard to see spots in night time pics, the contrast is enhanced and everything looks more dire. Still, it looks dire enough. There is verticillium in all natural soil, maples that are stressed become more susceptible and succumb. I think this is planted too deep, which may have increased stress, along of course with the horrible weather patterns we're all experiencing in this part of the world. I guess it looks dead, if it fails the scratch test, it's done. Garnet: I think you're in with a chance if you leave longer stubs and fix the planting depth. The cuts don't look like v., but pretty smudgy, so maybe just not very advanced. SK: does look like a classic v. wilt cross-section, the issue is always "where to cut", I think you're in the middle: not a long enough stub to let natural compartmentalization occur, not short enough, on the interior side of the V, to let wound wood grow, so for me it may die back into the crotch. The weak central stem would probably have died anyway, and it's not a bad idea to bring the tight V into a single leader, so if it lives it may be better for the pruning. I have maples that have lived for over 15 years with v. wilt, although the don't always look the greatest they can survive, although it has to be managed. One of our shirasawanums will lose a lot of wood this winter, for example, but it's already coming back from further down. Pulling all the maples and replacing the soil seems like an extreme measure, unless you know or suspect the tomatoes or some other nightshade family -- these hugely increase the amount of v. in the soil -- has bee grown there. My sense is that root washing with HP might do more to weaken the roots by damaging the mycorrhizal structures than anything else. Even when you add myc powder, it takes some time to get going and re-establish symbiosis with the roots.
What is the soil drainage situation like? Large scale branch die back is often a result of equally large scale root die back, associated with drowned roots if the weather is wet and the drainage is poor, or dessicated roots following a drought or heatwave. We've had the worst of both worlds of weather in Northamptonshire these last six or seven months. There are many pathogens that are opportunistic and will attack a tree via the roots if they start to suffer die back from drowning or whatever. I think of it like flu in humans, if the subject is healthy they are likely to successfully fight it off but if their strength and health is already compromised they could become very ill or die. Similar to what has already been advised by others, I would suggest digging up a couple of the maples to inspect the roots and to see what the soil conditions are like 20cm or more underground. Once you have seen a couple it will give you a better idea how to proceed with others. My guess is that the Jerre Schwarz will have very little healthy roots and will need to be disposed of. Others may be alright with a bit of surgery and planting in well drained containers, or even just raised up in their original planting position depending on how bad they are.
