AusBonsai

After posting this viewtopic.php?f=131&t=21062 about my red pine that died this spring I started candle pruning. While cutting the other old red pine I noticed some browning needles on it as well. I've had both yellowing (nutrition) and browning needles (various causes) before but the trees seem to recover up to now. In view of the gradual death of the other pine I'd like to know if anyone recognises this. Does not seem to have the banding normally seen with dothostroma and only on 1 branch of one red pine at the moment. Any suggestions?

Roots? Root aphids?

http://bonsaitonight.com/tag/root-aphids/

Thanks Joe. I'll have a look but did not notice anything when this one was repotted into this pot earlier in spring.

Well failing that it's either fungal, pest or climatic.

At least its not watering or potting mix

I would bundle that under climatic.

Perhaps Diplodia.
As a suggestion a broad-spectrum fungicide containing neem oil or copper salts/chloride?
Cheers

Hi Shibui, I would be inclined to remove it from its pot (if you haven't already done so) and look at the roots. If there are good white tips then perhaps some kind of fungous problem is in the branches. I find this rather unlikely but it's possible. Another possibility is sunburn or over heating. Of course if there are bad roots, that will be your problem. Its pale colour points to this to me.
Keep us posted as this is an important issue for us all!

p.s. If it turns out to be a fungus infection in the branches, finding something to cure it will be difficult. You will need a strong systemic and one which deals with the specific type. Root rot fungicides will be useless as will anything non systemic. The affected branches will die anyway so at least you could prune them off and spray with copper.

I was a little reluctant to lift it out of the pot because it was root pruned and re-potted in spring. It is also wired tightly into the pot because of the lean and few roots it is inclined to slowly fall over if not tied in tight.
BUT, because I'd like to find out what is going on I have untied and lifted it out a bit to give you a look at the new roots growing. Not all roots have spouted (see 2) but plenty of healthy ones showing so should be enough to keep it going.

I have sprayed all the red pines with leaf curl spray in case this is a foliar fungus.

Hi Shibu,
Roots look good me. I don't believe they are the problem. Hopefully the spray does the trick.

Do you know when the damage occurred? Could the hard root prune with an early hot spell be the answer?

The change of colour is recent Joe. So far only on the new growth and only on parts of 2 branches. Both hot weather and root prune could be factors but I have not noticed this before after either or both of those things have occurred. The recent demise of the other red pine may have me looking closer than usual though and worrying unnecessarily but still worth showing to other growers just in case this is something new or important for red pine health.