Help! Dothistroma?

TommyHallahan · Nov 2, 2018

I believe this pine I have (not exactly sure species) has Dothistroma, or some type of needle spot. I only just noticed it, so symptoms appearing in the last week or so. I read that copper fungicides should be applied just before new needles emerge, and through the growing season periodically...
Is there anything I can do starting now to help it out?
Should I apply fungicides now anyway?
Should I remove needles that are showing signs of infection? Or just wait til they fall off?

Any input will be greatly appreciated

TommyHallahan · Nov 2, 2018

0soyoung · Nov 2, 2018

Infected needles are just a spore source.

Most of the needles featured in your photo are so seriously gone that they are (what we could call) brown. Remove them and spray. Of course, you must have some needles on a branch or it will become a dead branch, but otherwise, remove affected needles as they appear and spray.

You are correct that the newly emergent needles are the most susceptible. If this infection is a serious as it appears, consider applying a systemic. It may cure mildly affected needles, but should be more effective in keeping next year's from getting infected than a spraying regimen.

TommyHallahan · Nov 3, 2018

0soyoung said:
Infected needles are just a spore source.

Most of the needles featured in your photo are so seriously gone that they are (what we could call) brown. Remove them and spray. Of course, you must have some needles on a branch or it will become a dead branch, but otherwise, remove affected needles as they appear and spray.

You are correct that the newly emergent needles are the most susceptible. If this infection is a serious as it appears, consider applying a systemic. It may cure mildly affected needles, but should be more effective in keeping next year's from getting infected than a spraying regimen.

So I should clip those all the way off, and spray straight away?
As far as "systemic" can you recommend a product I should look into?

TommyHallahan · Nov 3, 2018

Would this work?

0soyoung · Nov 3, 2018

TommyHallahan said:
So I should clip those all the way off, and spray straight away?

Yes.
I spray with a mix of 2 tablespoons 3% hydrogen peroxide (from the grocery/pharmacy) in a quart of water, but any antifungal you might have on hand (e.g., Daconyl) will do. Peroxide will nix any spores that are present on the leaf surfaces at the time. Daconyl and the like leave a residue that will actively kill incoming spores for a week or two.

TommyHallahan said:
As far as "systemic" can you recommend a product I should look into?

IIRC, Cleary's 3336 is what most bonsai folks use with pines. I think Bonide Infuse has the same active ingredient and, if so (again, IIRC), would also work. I think granular forms are preferred over liquid.

TommyHallahan · Nov 3, 2018

Thank you very much

bwaynef · Nov 3, 2018

Daconil treats most of what ails Pines. Dothistroma is only listed as treated by Phyton27 (or 35) of the 21 fungicides I've bothered to detail that are reasonably available. The systemic mentioned earlier in this thread doesn't list Dothistroma or very many needle blight type diseases. Its mostly for treating Pythium and Phytophthora (which I think are root based diseases).

I'd suggest you engage your extension office to find out exactly what it is. Barring that, I'd hit it with a broad-spectrum fungicide (Daconil, Clearys/Thiomyl, Mancozeb, Phyton[27|35]) and hope it improves.

Leo in N E Illinois · Nov 7, 2018

@bwaynef is correct. It is important to read labels before purchasing a fungicide. If the target disease is NOT listed on the product label, you should assume the product will NOT work. These are not totally harmless chemicals, spraying a chemical on a tree that does not cure your problem, is a waste of money, and could harm your tree. It will leave you thinking you helped the tree, and the disease will progress unaffected.

The label on a pesticide, fungicide or herbicide carries legal implications. The manufacturer is liable for the product to perform to the label, and the user is required to follow the label directions, particularly the safety precautions.

Leo in N E Illinois · Nov 7, 2018

Now after the safety warning, get some Phyton27, read label to make certain that the label includes treating Dothistroma.

0soyoung · Nov 7, 2018

btw, my favorite peroxide solution is broad spectrum.

bwaynef · Nov 8, 2018

I'd spend the time properly identifying the disease. That's going to take a bit of time now, but will save time trying to figure out why the chemicals you're throwing at it aren't working.

(Side note: I bought some shimpaku recently that came to me w/ a blight of some sort. At the prompting of an extension agent I happened to have shared a conversation with, he encouraged me to have the plants tested. The disease with which this material was afflicted is not among the lists of diseases controlled by any of the fungicides I've detailed. The service that ID'd it said it was similar to one that was controlled by several fungicides. I sprayed Thiomyl and removed the affected portions and its growing well again.

I say all that to explain that even if a disease isn't listed exactly, a broad-spectrum fungicide that treats similar diseases is likely to control others that aren't listed. The corollary: A fungicide geared toward root based diseases is unlikely to resolve needle-based issues.)

AJL · Nov 8, 2018

Its hard to tell from your photo but it doesnt look typical of usual Dothistroma symptoms.
I suggest quarantine it well away from any other pines in your collection and burn any dead/dying/symptomatic needles including all debris on the soil surface.
Its also possible the symptoms could be caused by aphids rather than a fungal disease.

0soyoung · Nov 8, 2018

AJL said:
Its also possible the symptoms could be caused by aphids rather than a fungal disease.

What you do or look for to tell which ir is?

AJL · Nov 9, 2018

0soyoung said:
What you do or look for to tell which ir is?

Sorry for my belated response -Im in a different time zone!! I had problems the last 2 years in early summer with aphids sap sucking the needles on my Mugos, leading to similar browning and dieback until I realised what was happening. I treated them successfully with dish washing detergent(eg Fairy Liquid- in water)
Our forestry industry here in Britain now has a big problem with Dothistroma in Corsican pine and Scots pine plantations
Generally older needles are affected and typically develop yellow and tan coloured spots and bands which rapidly turn reddish. Another characteristic symptom is the way the ends of infected needles then turn reddish-brown whilst the needle base remain green. Unfortunately the red banding is not always evident and the needles may have an overall brown or reddish coloration which can easily be confused with symptoms caused by other needle diseases.
Check out the Forest Research link below for more info
https://www.forestresearch.gov.uk/t...-cycle-of-dothistroma-red-band-needle-blight/

0soyoung · Nov 9, 2018

AJL said:
Sorry for my belated response -Im in a different time zone!! I had problems the last 2 years in early summer with aphids sap sucking the needles on my Mugos, leading to similar browning and dieback until I realised what was happening. I treated them successfully with dish washing detergent(eg Fairy Liquid- in water)
Our forestry industry here in Britain now has a big problem with Dothistroma in Corsican pine and Scots pine plantations
Generally older needles are affected and typically develop yellow and tan coloured spots and bands which rapidly turn reddish. Another characteristic symptom is the way the ends of infected needles then turn reddish-brown whilst the needle base remain green. Unfortunately the red banding is not always evident and the needles may have an overall brown or reddish coloration which can easily be confused with symptoms caused by other needle diseases.
Check out the Forest Research link below for more info
https://www.forestresearch.gov.uk/t...-cycle-of-dothistroma-red-band-needle-blight/

Excellent!

I see needle scale problems from time to time - small white stuff/things on the needles. You mentioned aphid possibilities. Do you mean wooly adelgids (which also appear as white fuzzy stuff but usually clustered around the bud bases) or some other kind. It would help @TommyHallahan and likely most of us to know what to look for to distinguish bug from fungi.

Thanks!

namnhi · Nov 9, 2018

What about these. I got these on a few of my pine every year. The are all on the same bench but only a few got these... Make it harder to figure out what it is. If it is fungus, I would suspect they all be impacted.

AJL · Nov 9, 2018

0soyoung said:
Thanks!

Osoyoung
I believe Woolly aphids or Adelgids are different names for the same or similar type of sap sucking of pests- it seems to depend whether youre a forester or gardener!! Im not sure what yours are called in USA but soapy water or a targetted contact insecticide will still kill them on a small bonsai scale infestation!! Its also easy enough to squash them with your fingers!!
If you look back at the previous thread of 16th March this year we discussed a similar issue - started by Clicio:- Suspect Dothistroma in JBP which turned out to be scale insect when we looked at the close up pictures! .
The symptoms caused by aphid /adelgids are similar to those caused by scale insect feeding. also look for sticky honeydew on needles and stems, excreted by the bugs, and you often see ants climbing around the plants feeding on the honeydew. Sometimes black sooty mould develops on the honeydew. Dieback of needles seems to happen later after the insect population has fed on the plant for a few weeks
Im trying to find photos of the aphid damage on my Mugos and will post them here if I havent deleted them already!

AJL · Nov 9, 2018

namnhi said:
What about these. I got these on a few of my pine every year. The are all on the same bench but only a few got these... Make it harder to figure out what it is. If it is fungus, I would suspect they all be impacted.
View attachment 216890 View attachment 216891 View attachment 216892

Nahmni Again difficult to diagnose from photos!!could this be caused by a physiological problem eg nutrient or root/ drainage issues ? the undamaged needles do look rather pale?

Nishant · Jul 2, 2020

0soyoung said:
Yes.
I spray with a mix of 2 tablespoons 3% hydrogen peroxide (from the grocery/pharmacy) in a quart of water, but any antifungal you might have on hand (e.g., Daconyl) will do. Peroxide will nix any spores that are present on the leaf surfaces at the time. Daconyl and the like leave a residue that will actively kill incoming spores for a week or two.

Hello Osoyoung, I am very keen to hear about your experience with Hydrogen Peroxide. Did you experiment this with Dothistroma, in perticular? My tree is suffering from Dothistroma and reaching out to everyone who can help/advise me.

I have used the copper based fungicide allready but copper is only protective for new needles. It does not kill the spores as such and it is always hard to get copper to cover all the needles. But if the the peroxide can kill spores, then nothing like that.

Picture of my needles infected with Dothistroma.

Help! Dothistroma?

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