Verticillium wilt?

[Dustbunny]

Hi everyone,

I was pruning my Japanese Maple last week, and found a black dot in the inside of the cut when I pruned it.
I'm wondering if it is Verticillium wilt..

All my Japanese Maples, Liquid Amber and Tridents have been suffering from something the last 2 or 3 years. They were slow growing with wilted or even black leaves.
The tridents were the worst and i sadly got rid of them. They were only seedlings and the hardest hit.
The liquid amber is back to itself, and my Japanese maples have been slowly recovering. They had a little bit of a slow start last spring, but then grew vigorously through the year.
Another branch I pruned looked healthy, but now has several spots on it.
Unfortunately this maple bled after pruning (it still is a little now) so I don't know if that caused a sooty mould type thing on the branch that initially looked fine.
I can't post any photos for some reason, but it's not a dark spot, it's a light, not opaque spot closer to the middle. There's no ring like I can see on photos of Verticillium wilt on google, so I'm not sure.
2 years ago in spring one of them had the same kind of spots on the trunk.

If anyone has any advice it would really help.
The tree is only 4 years old and has been kept on the dry side over winter.

Thanks!

[TimS]

Black or discolored rings in the wood can definitely be a marker of verticillium wilt, I'm closely monitoring my Kotohime i layered last year at the moment for the same issue (v-wilt) thought i haven't cut and branches back yet to see. It may well head to the bin before long.

Mine is leafing out at the moment, no discolored leaves yet, but black staining on the branches and tip die back. Are you seeing that on yours?

[Dustbunny]

Sorry to hear about yours.. honestly pests and diseases are the most difficult thing about bonsai I've found...
Mine doesn't have a black ring, just black spot.
There's no other sign of disease since early spring last year. It grew really well this past year.. but suffered in previous years.
A black ring on yours definitely sounds onimus ..

[shibui]

Some maples here have suffered from a wilting problem in spring. Soon after the leaves emerge the new shoots wilt then sometimes turn black and die. I'm pretty confident this only affects trees that have been too wet through winter and into spring. This may or may not be what's happening to your trees. A couple of mine have recovered after moving the pot to a better position on the bench with good air movement and making sure the soil dries more before the next watering. Wilted shoots here is usually associated with bark turning black at or near soil level. Usually by the time I notice the problem the black has already gone right round the trunk and it is too late to do anything.

There's another problem that affects the leaves of maples in spring. New leaves turn black or emerge distorted and small. Some growers have put that down to mites attacking the buds and treat with miticide, others swear it is a fungal infection and treat with fungicide. In most cases the trees recover as the weather warms up which begs the question of whether either or both treatments are effective. I have not treated the affected trees here and they recovered just the same. Again, keeping the pots a little drier through winter and spring seems to have reduced or eliminated the problem here.

Maples often bleed when pruned later in winter or spring. There's plenty of growers who say that's not a problem but I now prune earlier in winter to try to avoid excessive bleeding. I have found that maples do not bleed after root pruning so if you are worried about a tree that's bleeding after pruning, just do a repot and root prune and it stops immediately.

Photos for Ausbonsai must be under 1mb file size. Most phones and cameras create much bigger files now so you'll need to work out a way to compress the picture file. My phone gives the option to compress photo files when sending by email so I just email them to myself before trying to upload to Ausbonsai. Otherwise most photo software has an option to compress files.

for your trees

[Dustbunny]

I'm sorry for my late reply! Thank you, that's so helpful!
My trees have definitely been too wet or sitting in a bit of water at the bottom in previous winters. This year was a lot better, but I suspect it might take awhile to fully recover. The translation of bonsai should actually be 'learning the hard way' lol

Thankfully my maple has exploded in growth and is looking really healthy now.
I had the same problem with trident maple seedlings, they were wilting and distorted every year. A lot of them died, and any that were pruned or repotted died even quicker. In the end I got rid of the last of them as I just couldn't get it under control and was worried it would spread through the soil.
I regret that now. I found an old thread here about finding pests in the buds. I wish I'd seen it sooner and given spraying them a go.
Nevermind, they were young, I can always replace them.

I thought I was supposed to prune my Japanese maples when the buds swell, and that had worked until this year.
Bonsai-en on YouTube said to prune after the first flush of growth has hardened off, or in early autumn.
What are your thoughts on that?
You're closer in location to me so I imagine our winters would be more similar.
I also collected my seedlings from up a mountain, so they don't go dormant as quickly since they're used to colder winters. I think that complicates things for me a bit.


Once again thank you so much for your help and expertise! I feel like I'll still be a beginner in 50 years times

And thank you about the photos! The size being too big will definitely be my problem. Emailing them to myself is a brilliant solution, thanks!

[shibui]

I thought I was supposed to prune my Japanese maples when the buds swell, and that had worked until this year.
Bonsai-en on YouTube said to prune after the first flush of growth has hardened off, or in early autumn.
What are your thoughts on that?

I find that maples pruned around bud burst here 'bleed' quite badly. Some have said that's no problem because the trees are only losing water but many years ago a few bled badly and never recovered so I'm wary and other experienced growers report similar findings so more and more are going away from early spring pruning. Many of us now do structural pruning as the leaves are falling or soon after, through to around mid winter. No leaves means it is easier to see what you are dealing with and the trees rarely bleed early winter.
Other times for pruning deciduous is after the first flush is finished in spring and through summer. Pruning while the trees are active lets them heal quicker so less chances for infection, etc.
Avoid late autumn as sometimes the trees will respond with a flush of new growth. One crop of Japanese maples went right through winter with leaves and new shoots one year after pruning late one year. No long term damage and they reverted to normal growth pattern the next season but I now avoid late autumn for pruning.
Trimming light shoots ('pinching', even if scissors are used) happens whenever it is needed and does not seem to affect the trees, even early spring.

If I do need to do larger structural pruning close to spring I have found that root pruning stops bleeding so deciduous can be pruned if also repotted early spring before buds open. If you prune maples late and have significant bleeding a quick root prune stops it almost immediately.

I also collected my seedlings from up a mountain, so they don't go dormant as quickly since they're used to colder winters. I think that complicates things for me a bit.

Origin of seedlings will not affect how late or early trees go dormant or start growing. Individuals do not learn a calendar. They just respond to the environment around them so your seedlings collected from the mountain should move almost immediately to behaving as locally grown seedlings of the same species. Of course there will always be minor differences between individuals but that's nothing to do with the origins. I have many trident maples here and each has a slightly different clock from the others. Even down to one fusion project where one trunk changes colour before the others and leafs out a week before the other trunks in the same pot.

Your comment about bonsai being continual learning is very appropriate. I still find myself modifying practices after more than 40 years of practice.

[Dustbunny]

Thank you so much for being so detailed. It really helps!
I find it difficult when people say do such and such in Spring, or Autumn etc, as that is a 3 month time frame, and my Spring probably looks quite different to another person's spring in a different state or country.
It's much more helpful to say when the tree is doing such and such, then you should do x y and z.. so thank you! Very much appreciated.

Pruning in autumn is rather convenient too since there's less to do, and then I can focus on my evergreens in Spring.

I agree with the bleeding issue. Mine has thankfully gone nuts with growth and stopped bleeding. If fact, I think this is the most vigorous it's ever been, but I wouldn't want to try my luck every year.
If it can be avoided, that seems best to me.

Thank you once again! You really should write a book!