Yellowing Junipers after repot with new soil

[Shamino]

The photos below show three of my Junipers (Chinensis) and a Chinese Elm. This spring I repotted the second two junipers and the Elm with a new soil I obtained from a reputable dealer. I have always used an organic potting soil with no problems but the trees repotted in this soil are yellowing (the junipers) and have not leafed yet (the Elm). To treat the yellowing I have sprayed for mites ( Avid 0.15 SEC) and sprayed for juniper fungus (Phyto27), two problems I've had before and was able to correct. This time though, the two trees affected continue to get worse.

First, does anyone recognize this new soil of mine? You can see it well on the elm.
Second, would this soil require different watering than the previous organic soil? (I can't tell if I'm watering too much or too little...it's been fairly hot here in Maine and I've been watering every day.)
Third, any suggestions about what's going on here?

 

[shohin_branches]

Did you bare root the junipers when you repotted?

 

[Shamino]

Did you bare root the junipers when you repotted?

No...trimmed back 30-40% and repotted as I've done for the last 25 years with these.

 

[Deep Sea Diver]

The photos below show three of my Junipers (Chinensis) and a Chinese Elm. This spring I repotted the second two junipers and the Elm with a new soil I obtained from a reputable dealer. I have always used an organic potting soil with no problems but the trees repotted in this soil are yellowing (the junipers) and have not leafed yet (the Elm). To treat the yellowing I have sprayed for mites ( Avid 0.15 SEC) and sprayed for juniper fungus (Phyto27), two problems I've had before and was able to correct. This time though, the two trees affected continue to get worse.

First, does anyone recognize this new soil of mine? You can see it well on the elm.

Pretty hard to tell. Looks like crushed rock, possibly decomposed granite and a couple other rock types mixed with pine bark. Would recommend calling the dealer and getting the complete rundown.

Second, would this soil require different watering than the previous organic soil? (I can't tell if I'm watering too much or too little...it's been fairly hot here in Maine and I've been watering every day.)
Third, any suggestions about what's going on here?

Was the goal to eventually totally convert to the new media?

Will answer both the above questions at once. Yes and yes.

Looks like the trees have been over watered. It appears the new media is mostly inorganic and the old is organic media.

Having two dissimilar media creates a situation called called lensing. In this case the central root core, or shin of each tree is much more water absorbent than the outer ring of media. When this happens the media that drains best becomes dry faster, creating confusion as how to water. Usually in cases like this, and seemingly in this case, you are watering to keep the outer ring moist. As a result, the inner ring becomes overwatered, negatively affecting these trees. Usually root fungus kicks in and a cascade of not so good events occurs.

As Junipers really like to be dryish, the trees are resenting this extra water treatment and showing it by losing foliage.

Also adding the hazardous chemicals likely didn’t help the situation at all.

So, how to help?

The key area to be most concerned about in overwatering the shin. Use a chopstick to check the dryness of the core. When is approaching dry, water well. One can mist the outer ring lightly in between. If the trees recover, in 1-2 years one can convert the rest of the media to the new type.

Another method is to simply remove the outer ring of media and replace it with media similar in characteristics to the inner ring.

Good Luck

DSD sends

 

[Paradox]

Besides the yellow areas, the color of these trees looks off in general.

Looks like those branches that are entirely yellow are dead or dying.

Soil almost looks like it has a lot of small gravel/pebbles to me. Not the best soil imo.

 

[Deep Sea Diver]

Besides the yellow areas, the color of these trees looks off in general.

Looks like those branches that are entirely yellow are dead or dying.

Soil almost looks like it has a lot of small gravel/pebbles to me. Not the best soil imo.

Yep.

Do know some of the pros up in Maine and New Hampshire use some interesting media mixes successfully.

Like came from one of these providers. Would be fine if homogeneous throughout.

Cheers
DSD sends

 

[Paradox]

The elm has swelling buds.
Possible it's just sulking from the repot?
Bit concerning it's June and it hasn't broken buds though

 

[River's Edge]

The key area to be most concerned about in overwatering the shin. Use a chopstick to check the dryness of the core. When is approaching dry, water well. One can mist the outer ring lightly in between. If the trees recover, in 1-2 years one can convert the rest of the media to the new type.

Another method is to simply remove the outer ring of media and replace it with media similar in characteristics to the inner ring

This is the key aspect moving forward. The problem is not a particular type of substrate it is the dichotomy between the two types still present. Essentially the manner in which they have been used, not the products themselves. The two types require very different care routines with respect to watering and fertilizer creating the problem you have observed.
If I could I might suggest a compromise approach. Carefully remove e the trees, Tease out the side roots around the perimeter, replace the inorganic mix with 1/2 organic and 1/2 inorganic. This will aid the roots in venturing into the newer substrate and help to even out the water retention. Do not cut any further roots just gently tease out areas and refill between them gently to minimize damage. At the same time poke some holes through the older substrate to aid in oxygenation and drying out a bit quicker. Carefully done this should improve the outcome. There is lots of time left in the growing season for recovery.
Do try to ensure the Junipers in particular are staying a bit on the dry side. not so much the elm.
best of luck.

 

[Shamino]

Thanks all...I suspected a soil difference problem. I will look at the roots and assess. Is it me, or is the move to large particle inorganic soils a more modern thing? When I got into bonsai about 25 years ago, the recommended soils were much more organic, like that in the first photo. Would it help to shade the problem trees for a bit?

 

[Paradox]

Thanks all...I suspected a soil difference problem. I will look at the roots and assess. Is it me, or is the move to large particle inorganic soils a more modern thing? When I got into bonsai about 25 years ago, the recommended soils were much more organic, like that in the first photo. Would it help to shade the problem trees for a bit?

Yea a lot has changed in that time. At one time a mixture of peat and sand was the go-to. Even the national collection, or some of it was potted in that mix. There were people in my club still using that mix 5 years ago. Some still might. I used it when I was new to bonsai and found it to stay too wet and heavy. My tree's roots barely grew.

Not so any more. More open mixes have proven to be less problematic

 

[Wires_Guy_wires]

I put some itoigawa in pure pine bark and perlite, nothing else. And they've been yellow ever since. Healthy and growing fine, but closer to lemon than to lime green.

I think the pH as well as absorbtion by the soil medium plays a serious role.
Bark would go more acidic over time as it breaks down, so metal wash out easily, which would explain the color in my case.

 

[River's Edge]

Would it help to shade the problem trees for a bit?

Juniper do best in full sun and drier conditions. if you wish to place them in partial sun for a short period after disturbing the roots or repotting that can be beneficial. primarily avoiding higher temperatures and very hot sun when the trees have been recently worked! Repotting , wiring, heavy pruning etc!

 

[Shamino]

Some progress but I'm still a bit confused. This morning I took the two Shimpaku in question out of their pots, intending to follow River's Edge's advice. When I did, I found the roots to be healthy looking (see photos 1 and 2) and very little difference in moisture between the old soil and the new. Upon further inspection I took a closer look at tree number 3 in the original post and I took a photo of sections in that tree. They are Number 3 and number 4 below. Even though there's quite a bit of yellowing, there are still buds appearing on the healthy parts and even (photo 4) on the unhealthy parts. The new soil I used was from Brussels Bonsai and was labeled an "All Purpose Bonsai soil," also good for house plants. One line on the bag says it helps to hold moisture. (That's suspect.) Any comments after viewing the roots?

 

[Paradox]

I agree those roots look just fine.
Old soil does seem a bit heavy and wet.
Junipers don't like what we call 'wet feet', ie constantly very wet soil.

Keep them in morning sun and afternoon shade for a couple of weeks especially if it's going to be in the 80s during the day to let them recover from the repot. Water when they need it. Use a chopstick stuck in the soil to determine when they need water. Leave it in the pot and pull it out once a day and look at it. Water the tree when it is almost dry but not totally dry.

 

[River's Edge]

The roots on the outside appear healthy, difficult to determine the interior or gauge the moisture content difference with pictures that show the exterior.
The wiring may have affected individual branches or shoots as well.
I would monitor the watering to ensure continued recovery. If the old soil and new soil is comparable in particle size and moisture transfer than the recovery should be fine.
Often the difficulties we notice today particularly with conifers began several months ago! Can be a considerable time lag. Now that you are aware the roots are healthy you can proceed with careful watering routine and monitor the change.
best of luck