Blackens needles on Japanese white pine

Hello,
I need your advice on treatment of a WHITE PINE we've got.
The tree was repotted without damaging of the root ball in June of 2013. The used soil mixture is :
4-6 mm zeolite fraction 90%
bark with conifer needles layer 10%.
The tree is watered after at least 2 cm of the substrate gets dry. It is kept outside in the sun.
A week after we had a few days of extremely high temperature (40ºC)  the needles of the two low and one top branches on the south and the west sides of the tree got a yellowish color.
The pine was sprayed with antifungal drug.
A week after that the outside clusters of 3 secondary branches of the same branches got black.
At present the tree is kept under a 70% shadow net.
I suppose this pine has a root problem, am I right? If not, what it can be, what treatment should i use?
Thank you!

The coincidence of spraying with fungicide and then shortly there after the black needles appearing, suggests one possibility is that the application was the cause. Was the concentration according to label recommendations?

A second possibility, if you have had a lot of rain lately, the tree may be staying too wet. Wet soils can affect roots, which may first show as needles blackening, and dying.

A third possibility is that 70% shade cloth is too dark. If grown too shady, they become susceptible to diseases.

If your temperatures are not too extreme, I would give the tree full sun.

Not much you can do about the fungicide, except if you do use it again, keep notes and see if you get die back in other places. If I can get away with it, I try to avoid fungicides and insecticides unless I see a specific problem. Reason being that these chemicals can be harmful. I do not advocate routine applications unless you are certain from experience this is necessary.

Entire commercial growing operations have been wiped out due to a quality control issue with a fungicide or insecticide purchased by the nursery. Most famous was the massive incident involving Benomyl back in the early 1990's. But I heard recently that there may be a problem with a different fungicide this year, 2014, a nursery reported being wiped out by a fungicide application. It wasn't a brand I use, so I didn't pay attention to the details.

So it could be the chemicals, or it could be too much shade, or it could be wet roots (though this problem seems least likely of the 3).

Leo Schordje wrote:... ...If I can get away with it, I try to avoid fungicides and insecticides unless I see a specific problem. Reason being that these chemicals can be harmful. I do not advocate routine applications unless you are certain from experience this is necessary... ...

Leo, you are of course aware that knowledgeable bonsai artists suggest preventive spraying on conifers on a monthly base because by the time you can detect the spider mites and/or fungus attack the tree is most probably beyond the recovery point. I would like to know what do you think about this.
Thank you in advance.

my nellie wrote:

Leo Schordje wrote:... ...If I can get away with it, I try to avoid fungicides and insecticides unless I see a specific problem. Reason being that these chemicals can be harmful. I do not advocate routine applications unless you are certain from experience this is necessary... ...

Leo, you are of course aware that knowledgeable bonsai artists suggest preventive spraying on conifers on a monthly base because by the time you can detect the spider mites and/or fungus attack the tree is most probably beyond the recovery point. I would like to know what do you think about this.
Thank you in advance.

I have been raising orchids for nearly 40 years, and bonsai a little less, but nearly as long. Over the years, several times I have killed large numbers (more than 50) plants at a time by improperly applying fungicides. Yes, many recommend using these chemicals routinely, but there is always a risk. These are not harmless chemicals. Overdose your trees and you will damage them. Too weak a solution and you will create a resistant strain of your pest or disease. It is not always the best way to go, even if it is advocated by professionals as something they do in their commercial nurseries. Most fungi can be kept under control with good hygiene in the growing area and giving them good locations with adequate air movement and sufficient sunlight. If you are comfortable doing regular spraying of fungicide - go ahead. In this particular case, the black needles showed up right after spraying - without being there at the garden of the original poster, I can not know for certain whether the fungicide was the cause or not. I threw it out as a possibility. For my own collection - I choose to not use fungicides unless I see a specific problem that truly requires their use.

Leo, thank you for your reply.
Generally speaking I am against the use of chemicals, but you see... sometimes they are inevitable...
Lately a professional agriculturist has sold to me an organic product (mainly Phosphorus & Potassium) for prevention of fungal diseases which I have not yet applied. What do you think about such kind of products?

Thank you for your reply.
I used the Previcur Energy fungicide by Bayer Garden according to the included instruction.
Although i don't rule out this if my tree's crown can be judged as too thick, so the tree is weakened. I do not know how thick should be the crown of this pine (pinus parviflora pentaphylla koko no e) not to cause problems to the tree's health.
I put the tree under the shadow net after the first signs of disease appeared. It still gets full sun from east and west.
Before the problem started the pine was in the sun the whole day.
I dug the substrate and found that it's organic ingredient got separated from the mineral and formed a more absorbent layer with fine fraction.
I am not quite sure about how this kind of pines stands extremely high temperatures.

Dmitry wrote:Thank you for your reply.
I used the Previcur Energy fungicide by Bayer Garden according to the included instruction.
Although i don't rule out this if my tree's crown can be judged as too thick, so the tree is weakened. I do not know how thick should be the crown of this pine (pinus parviflora pentaphylla koko no e) not to cause problems to the tree's health.
I put the tree under the shadow net after the first signs of disease appeared. It still gets full sun from east and west.
Before the problem started the pine was in the sun the whole day.
I dug the substrate and found that it's organic ingredient got separated from the mineral and formed a more absorbent layer with fine fraction.
I am not quite sure about how this kind of pines stands extremely high temperatures.

your fungicide application may not have been the problem. Japanese White Pines do poorly in high temperatures, especially if your daytime gets warmer than 95F (35 C). They are affected more by warmth if the night time temperatures do not drop below 75 F (or about 25 C). They tolerate heat only if it gets cool at night.

What you describe in the potting media may very well be the cause of your black needles. If the roots are having problems, as roots die, needles and branches will die. I would do my best to improve the potting media now, this is the most likely cause of your needle loss.

The cultivar Kokonoe (Ko ko no e) is noted for being basally dominant, lower branches tend to be quite vigorous often at the expense of the central apex. So if your apex is bushy, and the lower branches thin, this is a sign the tree's health is in trouble. The whole tree should be bushy.

I would stop doing any "bonsai" on this tree and work at getting it healthy for the next couple years. No pruning, no wiring, no shaping. Plan on repotting in spring. Between now and then remove the surface layer of potting mix. Try to remove the organic layer without disturbing the roots. Replace this with a inorganic mineral type media, crushed granite is good, pumice and other media are good also. P. parviflora does not like soggy wet media. The roots need to just about dry out between watering. Most of us grow this pine in 100% or near 100% inorganic media.

You confirmed my supposition that the reason of tree's disease is extreme heat. Last year this pine got weakened for the same reasons of high temperatures, so for the moment I don't feel like shaping it. This year it got better and was feeling fine until heat started again. Unfortunately i can not remove the organic layer because it is in the middle of the pot. I am trying to water the tree every time the upper layer of the substrate gets dry. At the moment, there is no deterioration.
Thank you!

Hello.
In late August, did transshipment with sifting organics and fine fraction of the soil. The roots are damaged only at the top of the root ball, presumably because of its strong -this drying during the heat. Now, pine feels good.

Leo, you are of course aware that knowledgeable bonsai artists suggest preventive spraying on conifers on a monthly base because by the time you can detect the spider mites and/or fungus attack the tree is most probably beyond the recovery point. I would like to know what do you think about this.

I'm sorry, but "knowledgeable bonsai artists" aren't always the best horticultural experts. Just take a look at all the horticultural folklore that shows up in bonsai books.

The folks at our Agricultural Extension offices have always told me that there is no real value in preventative spray, and I learned the same thing in my Master Gardening classes. These days, sprays -- including fungicides -- available over the counter have very little lasting power. They kill bugs and diseases on contact and for perhaps a few hours afterward. Lime sulfur -- one of the old timers that is still with us -- despite all the silly rumors -- has perhaps the longest residual action around and it still is in the terms of a week or two at most.

A Registered Pesticide Applicator professional may be able to get his or her hands on chemicals with more lasting effect, but I'm quite sure I would not like to use any of that stuff on a bonsai that I and others handle regularly.

Since the beginning of the growth of the candles beginning to turn yellow needles at the ends of branches.

Hi Dmitry,

I have only just seen your thread, this advice might be a bit late, but do yourself a favor and lose the zeolite.

There are some strange chemical interactions with zeolite that I don't like. I am progressively reducing its percentage in my potting mixes. It does all sorts of strange things with pH, nitrogen as temperature fluctuates (wont bore everyone with the chemistry it just does).

If used in high concentrations it compacts down so roots have trouble penetrating and its too heavy for roots to push aside, in other words its too dense. Swap it out with something lighter and inert, such as perlite or pumice. If the zeolite is not mulched and shaded it will conduct heat from sunlight deep into the pot.

This has been my experience with zeolite.

Paul

Hi.
I'm a little confused, because for the first time confronted with the bad reviews of the zeolite. At the moment I have nothing to replace it, except river sand or granite chips.
Thank you.

I seem to have a habit of posting contradictory information, make of it what you will, its just my opinion.

I suggest you simply manage your potting mix for now and see if it is problematic for your environment.  

I have been using zeolite for about 5 years now, and I've slowly developed an understanding for it.  I currently use it a rate of about 20%-30% of my potting mix.

I often wonder about the raves for particular product and if anyone actually tests it over a period of time.  I think that people are raving about zeolite because it has high CEC, it seems that most of these people have no understanding of what CEC is and its impact in potting mixes.  But these are the same people that have a high profile in the bonsai world.  

I have found that the surface of the zeolite gets hot in the sun and conducts heat deep into the pot.  I use a bovine rectal thermometer to check soil temps.  These thermometers are very hardy and my thermometer literally lives outside.  I have used elevated timber planks to shade the soil when concerned about root scorching, this works much better than mulch.

You can test density by pushing a chopstick into different potting mixes, you get a feel for how much "push" you need. Compare it with the zeolite mix.

I have found soil chemistry with zeolite a little wobbly, I suggest simply watching soil pH.  White pine like acidic soil conditions, see if your pH drifts up over the summer.  Manutec makes a simple to use pH test kit that is accurate enough for this purpose, there may be something similar in your country.

These are things I have found with zeolite, all these symptoms will cause yellowing to some degree in white pines.  Just some thoughts for you.  Though zeolite may have nothing to do with your problems.

Paul

Hi.
I read reviews about the zeolite on aquarium forums and did not tempt fate, transshipment to a smaller pot with a soil mixture consisting of river sand, granite chips 1/1 and 5% pine bark.

Dmitry.

Yesterday, one day blackened needles and candles on the 3 secondary branches, today unchanged. What could be causing this rapid blackening of needles and candles?
It was cooling to + 10C, watering as usual, as the drying of the soil on 1,5-2cm.