Radiata Pines; Something peculiar happening

[craigw60]

I have a couple of radiata here one from Nel Saffin is getting quite old. I repotted mine last year in mid march and they didn't miss a beat, they hadn't been repotted for about 6 years which is the norm for me. I find the tighter they are in the pot the stronger they grow.
John I have been potting mine in diatomite and pine bark for many years.
Craigw

[FatMingsBonsai]

This is a good thread on these pines. I like the different approaches some bonsai growers are applying.

Thank you for sharing your ideas

[NBPCA]

I have been growing pines now for a few years in a Diatomite mix; 40% Diatomite(Maidenwell so far as I still have stock) 20% Zeolite, 20% Mini Pine Bark nuggets and 20% Coconut Peat/Coir Fibre and they are all doing fine. I have been repotting in early to mid March.

A very sick Red pine that had lost some branches has recovered its vigour over the last few years in this mix and potting regime.



Grant

[NBPCA]

Grant, I have a middle aged/old radiata (1960s). I live in Sydney and I repot mine in late winter to early spring. I do pruning all year round but Ive never ever hard pruned this one. I prune this one very lightly and conservatively.The biggest problem I have in Sydney for this pine is needle cast. Generally in spring, where rain on sunny days presents big problems for me. Theyre good conditions for the problem to spread, so now I carry the the tree under cover when it rains and pick off every single needle thats infected before it spreads from things such as insects and wind etc. You can see the black tiny spores when the needles reach a certain colour. It isnt Dothistroma that I have problems with, its cyclaneusma. I reckon the worst one to get. The old radiatas are not as resistant to these problems as the new ones. The new radiatas have been selected from trees that seem genetically resistant through selective growing from plantations that were devestated by this sort of problems. I never ever water any part of the needles, only the soil. The new radiatas dont seem to be effected or only effects them slightly from watering on its needles and I have alot of the new radiatas that Ive tested on.

Have you got any pics of the dying trees? How much did they prune off at one go? Do they seal the wounds? Can you give us a description of whats happening to the trees after cutting and during the dying phase?

I don't have any pics of the sick trees but the owner may be brave enough to post. I believe all his pines(Black, Red, Radiata, Pinaster) were repotted at the same time, around the last week in August; and all have thrived except some of the Radiatas.

Another grower lost an old one a few years ago but I would put that one down to being extremely root bound and probably a bit unhealthy and did too much at once; possibly.

Grant

[John Henry]

Hi All,Recently i have had discussions with Grant and other Bonsai addicts that have old Radiatas.As most of my trees are old and mainly pines. This year about 80% of my trees were due for re potting i have always potted in MADENWELL diatomite at a ratio of two parts Madenwell-two parts fine orchid nugetts-one part coco peat, this mix has worked great and has had no problems.As most of use know Maidenwell diatomite is no longer avalible, this year i switched over to MT SILVIA diatomite every thing else in the mix stayed the same,all my trees have gone great, the best year i have had for new growth and colour i potted approx 25 old pines Blacks- Scotts- some Mugos as well as Junipers/Deciduous and Cedars there was no major root work done on any tree.The problem is the four Radiata pines that were potted at the same time with in four weeks went limp and brown as if they had been burnt (pics attached).i would be very interested if any one else has had similar problems, all other pines are going great.

[Mojo Moyogi]

Hi John, I am looking at this post with interest as I currently have two 40yo P. radiata.

Just to clarify, were the Radiatas potted in spring this year or last summer/autumn? Also, if the Radiatas were repotted this spring, were the buds dormant, swelling or had they began to elongate into shoots?

I hope your trees shake off whatever has caused this problem.

Cheers,
Mojo

[John Henry]

Hi Mojo,I pot most of my trees i mid to late August i live in Melbourne near the coast where the climate is quite mild no frosts.
john

[Mojo Moyogi]

Thanks John,
Any controlled release fertiliser in the mix at repot? If so, what did you use? Did you take the usual Pine precaution of retaining some original soil with Mycorrhiza present?

I would doubt that the change to Mt Sylvia from Maidenwell would cause such dramatic differences in your trees, if anything Mt Sylvia is a little more alkaline, but conifers as a general rule should be fine with slight alkalinity.

Cheers,
Mojo

[John Henry]

Thanks Mojo,as in all my trees i add a small amount of native osmocoate when re potting then water in with a weak mix of seasol and have never had problems . At the same time of repotting i also repotted two radiatas in the only remaining mix containing Maidenwell diatomite they are both going gang busters.

[Grant Bowie]

Thanks for posting the photos John,

I also don't think that the MT Sylvia diatomite would be the cause of the browning and I also never blame Osmocote as I have been using it without drama for about 30 years.

Still a bit of a puzzle and i hope we can find out a likely cause.

A couple of the 4 may survive OK from what I can see in the photos.

For my trees and those at the collection I will tend to keep a good head of foliage in Autumn through to spring.

Grant

[Mojo Moyogi]

...and I also never blame Osmocote as I have been using it without drama for about 30 years....

Good evening Grant. You are not the only grower who has never had a problem with Osmocote. I still use and recommend it for it's convenience and for the most part, it's reliability.

The reason I asked a question that led to Osmocote being discussed here relates to the problem that can occur in Melbourne is that we often, as has been the case this year, limp very slowly out of winter and have long periods of below average temperatures in late winter to early spring. As trees start to show clear signs of waking from dormancy, through changes in colour of twigs and bud swelling, we repot because the time is right which is sensible bonsai horticulture. When prolonged cool, rainy and overcast weather persists for weeks at a time immediately after repotting, our trees sit around and do absolutely nothing above (and I assume below) soil level for 3-4 weeks. Having Osmocote in the mix when the tree is growing, even slowly, is usually problem free. Having Osmocote begin to release it's payload into cool moist soil with a tree that is just sitting waiting for soil warmth and to a lesser extent, sunshine can be problematic. I avoid using chemical fertilisers at all with Pines, Cedars and Larch. I find that organics work much better with beneficial microorganisms and suit my climate (which makes Melbourne look warm and dry) a lot better.

There are commercial varieties of Osmocote that do not release below or above given temperatures, I have been told by a few commecial nurseries in Vic that they prefer using these for the above reasons.
See here for a basic description: http://www.scottsasiapacific.com/pdfs/hort/Osmocote.pdf

John, I know that you have other trees that were repotted at the same time and are doing fine and this is a method that you have had success with for a long period. And as I wrote above, bud swell is a proven ideal time to repot just about all bonsai species. I have also read Brian's approach of repotting Radiatas in spring and seen and practiced craigw60's method of repotting Radiata's during summer (March is still horticultural summer in Melbourne) as well as repotting Cedars at the height of summer in February. Perhaps later repotting of Radiatas could be a precautionary measure for Melbourne's unpredictable entry into the growing season?

If you factor in Leo Koelwyn's observation (Leo is arguably Australia's most knowledgeable conifer nurserymen) that Pinus radiata has a weak root system, my theory at this early time is that a cooler and wetter than average August and early September, combined with a possible high dose of nutrients from Osmocote in the soil mix, may have given a few your trees a bit of a burn.

Just a theory though, I'm wish that I had something more concrete to go with, these are obvoiuosly valuable trees we are talking about.

Cheers,
Mojo

[Edward Scissorhand]

Henry, I dont know if you'll end up reading my post but the first four pics are pine needle cast. I need to inspect the needles and also need to know what kind of behaviours the needles underwent to tell you what they may be. But I can tell you what I suspect; 2nd, 3rd and 4th pic looks like dothistroma. The first pic, if its a different tree may have a different type of needle cast and probably needs to be verified under microcope, cant tell from the photo.

Root pruning, or hard branch pruning is considered weakening a tree and as such is susceptible to this type of disease, when the tree is at its weakest. Older radiatas are genetically weaker than the new ones.

If it were mine, this is what I would consider doing because the disease is cyclic and generally spring is the worst season:

1. Do not water the needles. When it rains, bring the tree inside or undercover.
2. Pick off any dead branches and especially the needles. Including the dead needles on top of your soil.
3. Always make sure that there arent any water nearby that could cause humidity.

The next thing you can do is use a preventative coating such as a copper fungicide and spray the whole tree covering all the needles. Keep in mind, this isnt a cure, just a prevention as the fungicide just puts a protective layer around the needles. Its important to pick off any infected needles with a tweezer rather than hands. Hands would more likely spread the spores. You will need to reapply the protective fungicide again and again for more than a year as the disease is cyclic. Once stabalised make sure to boost the tree with plenty of nitrogen, this will help foliage mass and will benefit by becoming more disease resistant.

Anyway good luck Henry, if youre listening.

[Scott Roxburgh]

Ed,

Can you circle the parts that indicate dothistroma? I am having trouble seeing what you are referring to?

Scott.

[Mojo Moyogi]

Edward I just read your first post on page one (don't know how I missed it) and the post above.

Refs on dothistroma
http://www.na.fs.fed.us/spfo/pubs/fidls ... a/doth.htm
http://www.nzffa.org.nz/farm-forestry-m ... le-blight/
http://www.nzffa.org.nz/farm-forestry-m ... e-diseases
http://www.dpi.vic.gov.au/forestry/pest ... dle-blight

Cheers,
Mojo


Edit: Scott, I can't see the red brown bands consistent with the disease either, hopefully there should be enough photo refs in the links above for John Henry to positively id/dismiss the disease at his end.

[Edward Scissorhand]

Scott, I dont know how to circle on photos. But maybe I can describe it for you. The parts where the dead needles have brown/reddish bands, and also in some parts of the photos, the needles, from the band towards the tip are dead.

Mojo, I can see the bands but are faint. They take on a more redder appearance over time perhaps.