Funny growth and die back on junipers

[matty-j]

Hey AB

I am having some issues with my junipers, there is some really weird growth and die back going on. I moved from Sydney to the Blue Mountains 12months ago, not sure if that has anything to do with what's going on?

My initial thoughts are to cut back any growth that is different or dead, it looks like it is spreading?

Any advice would be fantastic

Cheers
Matt

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[shibui]

I'm trying to work out what sort of juniper this is. Oops, there appears to be 2 different trees....
The different types of growth are juvenile and adult foliage. Most junipers have needle growth as juveniles. Some retain the sharp needle foliage all their lives but others change to the softer, more compact scale growth as the plant matures (shimpaku is one). Sometimes, under stress, the scale junipers revert to juvenile foliage - pruning shimpaku too hard can trigger that. I'm guessing your juniper has a mix of juvenile and adult foliage.

The dead parts are more of a worry but the fresh new growth does look promising for your trees.
Dead growth on junipers is often the result of being too dry at some stage - not enough to kill the entire plant, just enough for it to kill some parts to try to save its life.
Dead foliage can also occur after insect infestation - mites like junipers and are really tiny so often not noticed. Any spidery webs? To test, hold a sheet of paper under the branch and tap the branch. If present, mites will fall onto the sheet of paper and are more easily seen against the white background.
Too much shade can also cause dead foliage on many trees including juniper. Back of trees and lower areas are more at risk of shading.

[matty-j]

Thanks for the feedback Shibui

I have had these trees for at least 6 years and they have always had a consistent foliage type. The trees could have dried out and this explains the dead sections, I was using an automated system in Sydney and I am only hand watering now.

This is the only other photo I have of the trees from a few years ago.

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[matty-j]

I remembered that I had made some posts about two of the trees previously when I first got them, if that helps at all?

viewtopic.php?f=104&t=13305

viewtopic.php?f=131&t=13426

[AndrewAustralia]

Sorry just curious, the last image, the tree on the right, what species or variety is that?

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[matty-j]

Sorry just curious, the last image, the tree on the right, what species or variety is that?

Sent from my SM-G950F using Tapatalk

Thats a Shimpaku Juniper

[shibui]

In one of the previous threads you have named the tree as J. procumbens. It is usually considered to have needle foliage but true mature procumbens foliage is scale leaves - they are usually so busy growing that it is reasonably unusual to see it. Scale foliage usually appears on older, pot bound trees which are not growing very much. Needle foliage returns after repotting when the trees get a chance to grow again. I think you should see a return to normal foliage if the trees are fed and watered adequately or repotted.
The dead foliage could also be related to being pot bound as it becomes increasingly difficult for water to penetrate when the pot is crammed full of roots.

[Keep Calm and Ramify]

Hi Matty-j,
Have you checked in the pots for curl grubs?

[matty-j]

In one of the previous threads you have named the tree as J. procumbens. It is usually considered to have needle foliage but true mature procumbens foliage is scale leaves - they are usually so busy growing that it is reasonably unusual to see it. Scale foliage usually appears on older, pot bound trees which are not growing very much. Needle foliage returns after repotting when the trees get a chance to grow again. I think you should see a return to normal foliage if the trees are fed and watered adequately or repotted.
The dead foliage could also be related to being pot bound as it becomes increasingly difficult for water to penetrate when the pot is crammed full of roots.

Thanks for the info mate! It has been a few years since this my junipers have been repotted, I am always quite nervous repotting them compared to figs, natives or deciduous trees. I have been watering two of them inside larger containers so I know the root ball is submerged and well watered.

The taller pot with the cascade, I would have thought that dryness wouldn't be an issue with such a deep pot? I always thought tall pots retained a lot more moisture.

Hi Matty-j,
Have you checked in the pots for curl grubs?

I haven't checked for curl grubs, I use a diatomite, pumice and zeolite mix so I wouldn't have though there would be to many in there but I guess they are pesky buggers! I might have a look tomorrow and see what's going on.

Ideally I should wait until march or may before repotting? Maybe slightly early because the climate is a little colder up here.

[shibui]

The taller pot with the cascade, I would have thought that dryness wouldn't be an issue with such a deep pot? I always thought tall pots retained a lot more moisture.

It is probable that deeper pots actually dry out more than shallow ones. After watering the excess water drains out to a specific depth from the bottom of the pot (actual depends on consistency of the mix mostly) For argument sake say 1cm of saturated mix at the base of the pot. A 20cm deep pot with base 10x10cm (2 litres of mix total) therefore holds 100cc (base =10x10x1cm deep) of water in the saturated layer (as well as any still attached to the particles in the upper layers of the pot) A shallow pot 20x20x5cm deep (still 2 litres total mix) but base is now 400sqcm x1cm deep water table holds 400cc or 4 times as much water straight after excess water has drained.

There are a number of other factors that come into play such as larger surface area allows more water to evaporate to air, total amount of roots in the pot, total leaves on the tree, etc which makes the whole concept quite tricky but water retention is not as straightforward as most people imagine.

The longer you leave the trees, the more roots are filling the pots and the spaces between the soil particles which is where water normally sits after watering. I have found that eventually water just cannot penetrate into the root ball properly and despite good watering the inside of the root ball actually stays dry. Trees that have not been repotted for a few years suffer from drying far more than freshly repotted ones. Your pots would probably benefit from an occasional soak in a tub to allow water to soak the root ball properly.

[matty-j]

Thanks for that info Shuibi, that makes perfect sense.

Hopefully I can get these trees back on track with better watering and fertilising.

In your opinion when is the optimal temperature range to repot junipers?

[shibui]

I have only ever repotted junipers at the end of winter and spring. I tend to leave them until almost last because they don't seem to mind being root pruned even when they have new shoots which leads me to believe that dormancy is not critical when repotting. Just because I do something does not mean that's the best or only possibility.
Many others have moved to autumn repotting for many conifers and even a few doing deciduous trees at that time of year. We also have some experienced growers advocating repotting for cedars in mid summer. Last Bonsai Focus mag has an article from England saying that autumn is better than spring for collecting deciduous varieties there and I think that collecting wild trees reduces roots far more than simply repotting a bonsai.
The point being there appears to be a far wider window of opportunity for repotting than traditionally accepted.
I can't give any first hand experience of alternative repotting times. It will have to be your decision as to when to go ahead with these junipers. Others may like to offer more personal experiences.

[Grant Bowie]

The junipers look like squamata prostrata, a scale juniper similar to procumbens, which if left unfertilised and as it gets older can completely change to adult foliage. I have one I am trying to get to go 100% adult.(still working on it and not achieved yet)

Grant