Japanese White Pine needles brown at the tips

[tsamajama]

Hi Everyone,

I'm a noob. I've been growing some stock trees for about four years one of which is a beloved Japanese White Pine. I moved the tree from Northern VA to Boulder, CO a couple of years ago and the climate here is very different from VA - much drier, greater temp swings from day to night, and colder winters. It survived the first winter just fine but this year, the needles started turning brown at the tips and about half have fallen off. I suspect root rot; I probably overwatered in the winter. And the tree was left outside a few times well below freezing such that the roots likely froze. The candles appear to be forming, but I'm wondering if this is a case of root rot? If so, would Phyton 27 or 35 or some other systemic fungicide help? I cut way back on watering a few weeks ago, but the soil is still damp. The weather is finally becoming spring-like and warm, but the nights are in the high 30's to low 40's (Fahrenheit), so it will be a while before the soil dries out further. Any help or advice would be appreciated!

Tarek

 

[sorce]

Welcome to Crazy!

Any soil pics?
Maybe pics from the move till now, has it progressed?

I don't think it would be fungal with that move.

Cold sounds most likely, until soil is eliminated.

Sorce

 

[Dav4]

JWP are hardy to usda zone 4, so they can survive - 30 F as a landscape tree. Having the roots freeze solid and stay that way for months on end each winter is fine if the tree is sited out of the winter sun and wind and the pot is mulched to protect the roots from extreme cold. I do suspect cold damage, but I also suspect there may be other contributing factors, such as location during winter and soil composition.

 

[Pj86]

From the picture, this looks like a root issue. The indicators are that the whole tree is affected and not just spots.

I would not treat it with phyton, unless you see and identify fungus issues which I do not see from the picture. If you fix the root issue first you will see improvements in a couple of months up to a year.

I have a mugo pine that looked very similar. I tilted the pot for the remainder of the growing season and made sure that my watering was correct all the time. A year later, the pine started putting out new candles. I carefully repotted it into a root maker pot and changed the soil composition to have more aeration. It will be a 2-3 year recovery.

 

[tsamajama]

Sorce, here are some more pictures. I don't see any actual fungus, though some of the roots are black and a little slimy (bacterial biofilm?). The grower says it's grafted onto Japanese black pine stock, but I don't see a noticeable scar. As for last winter, I brought the tree in to the foyer for the house when temps were forecast to be below ~ 28 F, but missed a few nights. And it was protected from wind and in the shade.

So, for the summer:
• Don't use Phyton
• Don't overwater, tilt to help with drainage

Any thoughts on repotting into better draining soil? I've read not to repot a tree in distress but Peter Chan claims sphagnum moss is a miracle cure for root issue and I've seen him repot trees with root issues into well draining soil with sphagnum moss. Thoughts on that?

Thanks everyone!

Tarek

 

[BonsaiFurLife]

Nutrient burn?

 

[tsamajama]

Nutrient burn?

My sense is no. I use a diluted liquid bonsai fertilizer (~25% strength of recommended dilution) with every other watering during the growing season, none in the winter. Last application was October 2020. Discoloration was first noticed in late March.

 

[Dav4]

The JBP root stock limits the cold hardiness by at least one zone. That, combined with the heavy, organic soil it's in, may have contributed to some root damage.

 

[tsamajama]

The JBP root stock limits the cold hardiness by at least one zone. That, combined with the heavy, organic soil it's in, may have contributed to some root damage.

Thanks, Dav4! So would repotting in better draining soil, a mix of akadama, grit, and some organic matter (I'd look up a specific mix for JWP), be good? Or is it better to wait to repot until it recovers somewhat, assuming it's on it's way to recovering! The soil is what it was purchased in has been grown in for several years.

 

[Dav4]

Thanks, Dav4! So would repotting in better draining soil, a mix of akadama, grit, and some organic matter (I'd look up a specific mix for JWP), be good? Or is it better to wait to repot until it recovers somewhat, assuming it's on it's way to recovering! The soil is what it was purchased in has been grown in for several years.

Hard to say. The needle damage is significant, as the tree in this weakened state will struggle to recover and a re-pot will inflict more damage. If the roots are truly black and slimy, you may not have a choice, meaning the re-pot may be life saving.

 

[FiestaRed]

Tsamajama, did you ever get anywhere with your JWP at all, did the tree respond to any form of care?

 

[Potawatomi13]

Tsamajama, did you ever get anywhere with your JWP at all, did the tree respond to any form of care?

Seconded.