Need Help Treating Needle Cast on Mugo Pine

[Ceiling_Tyl]

Hi All,

I'm looking for some advice on treating needle cast on my mugo. I noticed the needles turning yellow last month and after keeping an eye on it, determined the cause was needle cast. Worried about losing my back-buds, I went in with forceps and removed or trimmed any infected needles before spraying with Daconil. I followed up with Daconil several days later, and have sprayed it once a week since (5-6 times total). But I'm still losing needles. Buds will grow back but I worry about losing some of my lower branches. What else can I do to help this poor tree?

Initial infection before treatment:



____________________________________________________________________________________
After pruning:


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Photo from yesterday: (a bit hard to tell, but needle cast is still there affecting the foliage)





I live in Southern Ohio. I reference Vance Wood's instructions for pine care and adjust to my weather/soil mix. I have another mugo of similar age that is absolutely thriving.

 

[jszg]

I've had good luck with thiophanate methyl applied just as the candles extend: my understanding is that the damage done is permanent to the needle, but spraying now will stop any spores from spreading. Dying branchlets makes me think there might be a more serious issue with the roots, but that's as far as my experience extends.

 

[Deep Sea Diver]

Mugos can be needle cast magnets if not attended to. If it’s been treated wil Daconil, one might want to hold off at least a month on applying more fungicides.

The damage will not go away, let it will be halted. Also recall old needles are shouting off at this time of the year.

A couple preventive things to do.

Clean the media and sweep away all the debris around around the tree, then get the tree up off the ground. If the media is soggy, chock up one side of the pot to enhance drainage.

Finally periodically spray the needles with copper during dry spells to enhance its effect… 2-3x in the winter and for sure in the spring. One could also use 3TBSP 3% H2O2 to QT H2O once a month the water the media with.

Just a few thoughts.

Cheers
DSD sends

 

[bwaynef]

I've found mugo to be much less susceptible to fungal pathogens than JBP. To the point that I thought they weren't susceptible. I'm treating my JBP w/ Daconil, Copper, and Thiomyl to pretty good effect.

 

[Deep Sea Diver]

Welcome to the Seattle Rain Festival started last weekend!

There’s one heavy needled cultivar in the collection here that seems to be most susceptible. Two others with finer needles seem not to have an issue.

It needs attention every year while the others, turn their noses up to fungus. The tree is really robust grouse back budding with a vengeance, yet we prefer to use the less innocuous remedies. Knocks it down… only to reappear in a year or two.

Thiomyl is relatively new to me, so I looked up the sds again. Here it is. It’s one to be really careful of, especially on the respiration side.

https://firstrays.com/wp/PDF/Thiomyl-SDS.pdf

Daconil is a well known medium level carcinogen. Another to be wary when using and storing.

https://assets.syngenta-us.com/pdf/msds/Daconil_2787_15724_en_SDS.pdf

Cheers
DSD sends

 

[Lorax7]

My understanding is that you can’t really stop needlecast from affecting the needles that are already affected. The way you get rid of it is by prophylactically treating the new needles in the spring while they are tender (i.e., haven’t yet hardened off with the waxy coating that mature needles have). By doing that, you prevent needlecast from getting into the new needles, stopping the cycle.

That’s what I did when my JBP had it and the treatment was successful.

 

[Paradox]

The needle cast you see this year infected the tree last year. Those needles will not heal.

Best way to deal with needle cast and other fungal infections is to pick 2 different fungal treatments (ie copper based and daconil) and alternate spraying them every 2 weeks from May through September/October.

Some also use a granular fungal product called Infuse by Bonide in early May and again at the end of July/beginning of August.

 

[Deep Sea Diver]

Like the rotation method, although it seems pretty frequent.

Wondering….. Are there any other fungicides that could be used?

Here’s the SDS for Infuse It got me on the suspected mutagen part… don’t like having stuff like this around the grandkids who get into everything.

Wondering what’s used in the EU @Glaucus @Wires_Guy_wires @leatherback ?

cheers
DSD sends

 

[jszg]

I am currently studying chemistry for a living- the safety stuff in SDS docs can be (to my desensitized eyes,) extreme: better safe than sorry , etc. I would note the oral LD50 is very high. 7.5g/kg is a toxic dose higher than most household chemicals.

I suspect the high toxicity to the lungs is not due to the fungicide but rather to the silica gel and kaolin dust, which they may not prefer to reveal as a trade secret. Silica gel can destroy lungs very easily, uniquely, and lethally with chronic exposure, with a similar mechanism to asbestos.

My advice is to wear gloves and a N95 mask, but nothing more.

 

[Deep Sea Diver]

I am currently studying chemistry for a living- the safety stuff in SDS docs can be (to my desensitized eyes,) extreme: better safe than sorry , etc. I would note the oral LD50 is very high. 7.5g/kg is a toxic dose higher than most household chemicals.

I suspect the high toxicity to the lungs is not due to the fungicide but rather to the silica gel and kaolin dust, which they may not prefer to reveal as a trade secret. Silica gel can destroy lungs very easily, uniquely, and lethally with chronic exposure, with a similar mechanism to asbestos.

Gosh….

Worked in labs at sea, in the ice pack and ashore for over 40 years. My years of handling hazardous materials. Got paid as a Chemical Hygiene Officer for a couple decades too. One might strongly consider following the SDS in your future career to the letter. Us old CHO’s have reams of stories of folks who didn’t… that were injured and or no longer working in their organization.

As a bonsai hobbyist, your life your choice… but at least one might think to make an informed choice?

My advice is to wear gloves and a N95 mask, but nothing more.

…and therein is the rub in online forums… my advice would most decidedly differ.

Please Be Safe
DSD sends

 

[Wires_Guy_wires]

Like the rotation method, although it seems pretty frequent.

Wondering….. Are there any other fungicides that could be used?

Here’s the SDS for Infuse It got me on the suspected mutagen part… don’t like having stuff like this around the grandkids who get into everything.

Wondering what’s used in the EU @Glaucus @Wires_Guy_wires @leatherback ?

cheers
DSD sends

My trees don't get needlecast. Maybe five to ten affected needles a year in the whole garden. So I don't have to treat it with anything other than a scissor.
There's a fungus in my soil that seems to be pumping enough antibiotics to vaccinate my pines. And it seems to be transferrable to other pots.
Usually I do a copper sulphate spray in spring, but I forgot this year.

 

[Paradox]

Like the rotation method, although it seems pretty frequent.

Wondering….. Are there any other fungicides that could be used?

Here’s the SDS for Infuse It got me on the suspected mutagen part… don’t like having stuff like this around the grandkids who get into everything.

Wondering what’s used in the EU @Glaucus @Wires_Guy_wires @leatherback ?

cheers
DSD sends

Every 2 weeks is what I have seen recommended by Adair and others to prevent fungal infections during the worst time of the year (higher humidity).
That way each preventative gets applied once per month.
Might be able to do once a month and just alternate product each month? I don't know.

 

[Glaucus]

The thing with MSDS sometimes is that you want to dissolve 1 gram of something in a fume hood, and you read a MSDS which also written for people who throw around bags of 25kg of this stuff, open it up, dissolve it in a reaction vat, etc.
The MSDS usually is also about pure substances, unless you have the MSDS specifically for a certain dilution or mixture.
Also matters a lot of the toxicity is acute or chronic.

Chlorothalonil, which is a pretty molecule, (active ingredient of Daconil) does have some scary lines in the MSDS. And it was banned in the EU for bee and other environmental reasons. Not for being a "possible human carcinogen" to people working with the chemical.
Especially fungicides are molecules selected to be toxic to fungal cells. And fungal cells are not that different to animal cells. Which usually means that fungicides are not so nice for humans.
But it turns out that the metabolites of chlorothalonil were actually the reason it was harmful to the environment.
Folpet seems to be designated as the main replacement (as mancozeb was also banned).

Chlorothalonil will probably also hit your mycorrhiza. So better not use this stuff unless you have fighting a clear known fungal pathogen.

This Dutch company has a list of what to use on trees:

https://karobv.azureedge.net/1674817332/dossier-art/BRZZSBOOMKWEKERIJ/Spuitadvieskaart-boomkwekerij%20KaRo.pdf

Almost all of these are regulated and require a license, so for commercial growers only. In part because misuse can result in resistant pests.
List doesn't include needlecast though.

I have seen some funny comments online that the Netherlands banned all pesticides, insecticides, fungicides, miticides, herbicides, etc. Not true. We follow EU rules and we might even be one of the countries lobbying against these bans.

 

[Deep Sea Diver]

Thanks for the information. Just to clearly correct the record:

SDS’s and their hazard statements and pictographs are created to document hazards to Humans.

Dilution to recommended strength does not lessen the hazard (we’ve been through this before btw). It is the hazard.

SDS do include statements nowadays for aquatic life etc, but these are additional information.

Many chemical and agricultural industries and states in the US and otherwise have perpetually lobbied against SDS scientific data for decades. Over a half a century ago these lobbies first gained momentum trying to lobby against the banning of DDT.

@Glaucus Thanks for the reference. It would be interesting to see if there was an English translation. It might immediately prove useful.

cheers
DSD sends

 

[Ceiling_Tyl]

Y'all are awesome. Thanks so much for sharing your wisdom and experience. Since the condition hasn't improved, I'm inclined to believe @Paradox 's hypothesis about the infection lingering from last year and just now becoming visible on needles. I remembered some needle cast, but it seemed much more mild. I plan to leave it for about two weeks and try another fungicide (I'll see what I can get locally from the recommended list). This is a hard lesson learned in preventative maintenance for me. Hopefully it doesn't cost me the mugo.

 

[Paradox]

Y'all are awesome. Thanks so much for sharing your wisdom and experience. Since the condition hasn't improved, I'm inclined to believe @Paradox 's hypothesis about the infection lingering from last year and just now becoming visible on needles. I remembered some needle cast, but it seemed much more mild. I plan to leave it for about two weeks and try another fungicide (I'll see what I can get locally from the recommended list). This is a hard lesson learned in preventative maintenance for me. Hopefully it doesn't cost me the mugo.

It's not a hypothesis. It's the factual life cycle of the fungus. Do some research on needle cast and you'll find that information on state agricultural station web pages.

 

[Lorax7]

Y'all are awesome. Thanks so much for sharing your wisdom and experience. Since the condition hasn't improved, I'm inclined to believe @Paradox 's hypothesis about the infection lingering from last year and just now becoming visible on needles. I remembered some needle cast, but it seemed much more mild. I plan to leave it for about two weeks and try another fungicide (I'll see what I can get locally from the recommended list). This is a hard lesson learned in preventative maintenance for me. Hopefully it doesn't cost me the mugo.

I wouldn’t bother with any further applications of fungicide this season. It can’t help the needles that are already infected. Spring is the time to apply in order to break the cycle.