Sick Japanese Maple Advice

[Jasohughes]

Hi all,

Hoping someone might be able to help me here. I've a maple that was growing quite nicely but have made a huge mistake it seems and sprayed it with Yates Pyrethrum Insect Pest to control a quickly growing mite problem.

Since the spray two days ago, the mites have all but gone, but most of the leaves have wilted (including the fully grown leaves).

I'd expected some of the new growth to maybe succumb if I'd happened to accidentally spray this but not the majority of the plant!

It's a well grown and established tree so hoping that it's not the end of it and simply a learning for next time.

Thanks
Jason

[TimS]

Hmm, I sprayed one of my Arakawa JM’s with the same product 2 days ago and haven’t had any issues to report whatsoever.

Was the tree in full sun when you sprayed it? Was the soil dry? How much did you apply to the plant? Any other info about the plant, it’s general health, location or other factors you can think of? As I say my JM as been totally fine with being sprayed by that product.

[Jasohughes]

Sprayed it around 6pm so no sun. Soil wasn't completely dry, would have watered it sometime prior to midday.

General health it was growing really nicely, no other issues. Is in a spot where it's been in the same place for a year and not other real issues I can think of apart from I've gone too aggressive on the application.

When I noticed the mites they were relatively established and then took four (sunny) days for the product to be available to pickup (Victoria ).

By then, there was quite a few established areas all throughout the plant so it got a pretty good spray to be honest!

Is quite a sizeable established tree (40 years) and looks like a fair bit of the growth isn't happy with the spray, but just hoping it'll bounce back given there's still a fair bit of growing time this season!

Thanks

[shibui]

Almost certainly a coincidence that wilt started around the time you sprayed it.
There is a fungal infection that affects JM especially around the time they shoot in spring. Look for black areas on the trunk, particularly right near ground level.
Photos would help to Id the problem.
Fungicide should not make it worse and may even help if it is not already too late. Make sure the soil is drier rather than always wet.

[kvan64]

Sorry to hear about your negative experience with insecticides. Right now, I would not try to treat the problem with any further chemicals. Yes, like Shibui said, check for signs of fungal infection too. I would remove all infected foliage, keep it in partly shaded area I would recommend you to check the soil with your fingers and only moist it when it’s nearly dry. I would start with diluted Seasol and SuperThrive when there is new growth from affected area.
All the best.
DK

[Jasohughes]

Thanks for your feedback all, your time is much appreciated.

I've attached a couple of photos of the trunk close to the soil - there are a couple of black areas but there has been no change to this since the plant came into my possession (it was a gift and I'm very nervous about it's care!)

Yesterday I had to remove a fair bit of foliage, this morning will need to do a little but thankfully foliage wilt hasn't progressed anywhere near as significantly overnight.

Will take your advice on watering as well - appreciate that. Has been a blessing and a curse this gift, not sure it's the greatest starter bonsai for a beginner - I've been growing some Black Pines from seed as I figured I should understand the complete process instead of just inheriting someone elses hard work, but the learning there is going to take time!

[TimS]

That green stuff called liverwort on the surface is a big red flag that it has been/ is being over watered and retaining the water not draining it away.

I would scrape of all of it as soon as possible so you can see the soil surface and then post is back a photo of how the soil itself looks. If it hasn’t been repotted for a long time it could be that not enough air is able to penetrate to the root zone

[Jasohughes]

Again, really appreciate the advice.

If it needs a repot I'm in Melbourne and would certainly need some recommendations where to get this done. Not sure I'd have the minerals to attempt this on my own this time round.

Not sure when last repot was but I've had it for about 8 months now.

I'd watered this 24 hours ago, soil was damp but not saturated in any spot. When watering I have noticed the water takes longer to drain through than when I'd first got this, indicating it is retaining more water.

[Stu]

A few suggestions:

• I would check bonsai nurseries for help but during Covid I don't know who could repot for you.

• You have probably missed the boat for repotting this year and cutting the roots of a sick tree may make it worse although some say Japanese Maples can handle repotting out of dormancy.

• You could use a chopstick or a power drill to bore holes in the soil allowing better drainage.

• Remove the tree from the pot and place it in a larger or at least deeper pot leaving the existing soil untouched until next Winter. Use bonsai soil.

Good luck.

[TimS]

Yep that is in need of fresh soil if it was watered 24 hours ago. Hard with the lockdown we are having at the moment, but I would say take it to Bonsai Sensation in Narre Warren. Not sure if they are open during lockdown, but it’s more than likely outside your area of travel anyway. They definitely will repot for you (for a price) but they are always good with advice and how to best look after the health of the tree.

I had the same issue with a JM about 18 months ago, and I repotted it totally out of season just clearing out the old soil and putting fresh bonsai mix in again, not cutting any roots, and it has recovered nicely now. Mind you mine was going into autumn dormancy not into spring growth so it’s a little different.

Hold back on the watering for now, and perhaps use a wooden chopstick to poke a few holes in the surface of the soil to let a bit of air get in. It’s not ideal but it’s better than nothing at this point. Also you can stick the chopstick into the soil and check how wet it is by pulling it out and seeing if the end of the chopstick is wet. Again not ideal but one way to at least visually see what is going on below the surface.

[treeman]

Way way WAY too much fertilizer. After repotting JMs I give then no fertilizer at all for months.
Too much will fast track the mix breaking down and any fungus diseases.
The trick with keeping them healthy is not fertilizer but repotting. Small ones every year, larger ones ever 2.

[Jasohughes]

The fertiliser is from the last 3 instances, two prior to winter and one since seeing new growth. I wasn't sure whether to take the old stuff out, but sounds like I should and also sounds like I need to be a lot more time invested in this project for it to be a long term healthy success, instead of simply fixing issues when they arise.

I've made some holes in the soil and will look at transferring to a larger pot when I'm able to get out and find one and can take out to Narre Warren once we get a bit of lockdown reprieve.

Thanks for the advice all. I'm very quickly learning a fair bit from these forums and also all the help you provide the couple of times I've posted!