Black spot advice.

[Michigan Tree Murderer]

My Chinese Elm has what appears to be black spot. I searched the Forum and read quite a bit about it. Defoliate and spray with fungicide.
Little info. It's outside in full sun. I've only owned it for a year. It's been cloudy and rainy for the last two weeks. It's in well draining soil. I have sprayed the leaves for bugs when it's hot and sunny and I saw bugs on other trees. I marked the trouble spots in red. Leaves turning black and dying.



My questions are.

Can I defoliate in July? Take all the leaves off or just the infected?

From what I read a repot would help get the fungus out of the pot, but I can't do that in summer. Is there anything else I can do?

I've sprayed it with this a few times, but I may have been too late.




I have another elm that completely fine.

 

[bdmatt]

Complete defoliation, including healthy leaves. Then apply infuse granular fungicide.

Black spot targets new growth first, then old growth next. So if the old leaves are still present, there's a chance of the black spot coming back. Applying a systemic fungicide will help inoculate the tree. I prefer a granule in this case.

@Housguy 's father had a chinese elm with black spot back in May. I defoliated it and applied infuse. The tree bounced back in 2 weeks and was still healthy a month later. His other elms were also infected, but they weren't defoliated completely and still had black spot by the time I brought back the other tree. Here's a before and after 2 weeks:



July defoliation is fine, it's better than having the tree deal with black spot. If you're scared, then remove only the infected secondary or tertiary branches. If the tree continues to decline, you'll have to defoliate it completely. Which is why I prefer just to defoliate it all at once.

 

[Michigan Tree Murderer]

Complete defoliation, including healthy leaves. Then apply infuse granular fungicide.

Black spot targets new growth first, then old growth next. So if the old leaves are still present, there's a chance of the black spot coming back. Applying a systemic fungicide will help inoculate the tree. I prefer a granule in this case.

@Housguy 's father had a chinese elm with black spot back in May. I defoliated it and applied infuse. The tree bounced back in 2 weeks and was still healthy a month later. His other elms were also infected, but they weren't defoliated completely and still had black spot by the time I brought back the other tree. Here's a before and after 2 weeks:



July defoliation is fine, it's better than having the tree deal with black spot. If you're scared, then remove only the infected secondary or tertiary branches. If the tree continues to decline, you'll have to defoliate it completely. Which is why I prefer just to defoliate it all at once.

Awesome info. I recently bought some infuse & @Housguy is my main man cork bark oak bro. Thanks for the quality advice.

 

[Michigan Tree Murderer]

@bdmatt Just a follow up to say your advice worked great. Leaves are looking really healthy. Do you do a repeat application of infuse granules every 30 days or so as a preventative measure?



Now of to do some trimming.

 

[bdmatt]

Just a follow up to say your advice worked great. Leaves are looking really healthy. Do you do a repeat application of infuse granules every 30 days or so as a preventative measure?

Happy to hear your trees healthy!

Not necessary, but if you really want to apply more granules as a preventative measure- do so every 3 to 4 months. Assuming you put the recommended amount, you don't need to apply infuse for a while. Once a year application during spring is perfect on top of any other insecticides/fungicides you decide to use. However, its also safe to apply every 3 to 4 months, just at slightly less dosage. The granules take a VERY long time to break down, so it's easy to over do it applying every month because the granules just build up.

Some tips about application- Infuse is most effective when the tree is actively building foliage because it'll readily take up the infuse into the leaves. This is why I personally apply it during early spring and fall(after summer dormancy).

 

[Deep Sea Diver]

Glad this worked for your Elm’s black spot issue,

Given you are using and storing Infuse please be advised there are some definite downsides to using this product for humans, environmentally and storage wise to be aware of. Its long stay time can exacerbate these issues.

Here’s the Safety data sheet.

Be careful out there .
DSD sends

 

[Michigan Tree Murderer]

Happy to hear your trees healthy!

Not necessary, but if you really want to apply more granules as a preventative measure- do so every 3 to 4 months. Assuming you put the recommended amount, you don't need to apply infuse for a while. Once a year application during spring is perfect on top of any other insecticides/fungicides you decide to use. However, its also safe to apply every 3 to 4 months, just at slightly less dosage. The granules take a VERY long time to break down, so it's easy to over do it applying every month because the granules just build up.

Some tips about application- Infuse is most effective when the tree is actively building foliage because it'll readily take up the infuse into the leaves. This is why I personally apply it during early spring and fall(after summer dormancy).

Okay, good to know. I'll definitely wait till next year. Thanks again for sharing your knowledge and experience. Much appreciated.

 

[Michigan Tree Murderer]

Glad this worked for your Elm’s black spot issue,

Given you are using and storing Infuse please be advised there are some definite downsides to using this product for humans, environmentally and storage wise to be aware of. Its long stay time can exacerbate these issues.

Here’s the Safety data sheet.

Be careful out there .
DSD sends

Good to know. Thanks.

 

[ACooke]

Hey all,

I noticed the early stages of what seems to be black spot on a chinese elm I'm ground growing yesterday so was planning on following the above in the coming weeks - it's starting to slowly cool down here in Australia so timing wise, it probably works out well.

My question is if if there's any direct alternatives to Bonide Infuse, within which I believe the active ingredient is propiconazole within the 'concentrate' form or specifically the granular form, it seems to be thiophanate. Neither of which - from what I see - are available here in sub-commercial quantities and it doesn't seem to be available under alternative brands like imidacloprid is through RichGro vs Bayer 3-in-1.

So, I thought someone with more knowledge and savviness than myself might know of adjacent and very similar active ingredients to look have a look for?
Failing that, there's systemic treatment for 'Black spot and Fungus' using 'Flutriafol' through RichGro 'Black Spot and Fungus Killa', and copper products are common.

At this stage I'll probably just stumble my way in to the Flutriafol system treatment and see how that goes unless there's any advice against that or suggestions; I'm not sure how many of the 'black spot' treatments are targeted at 'black spot' in roses, and if that differs or not.

Anyway, sorry for the drivel and thanks for another helpful thread.

 

[Deep Sea Diver]

First ensure thred key environmental controls are in place,

1. ensure tree has plenty of ventilation and room between plants,
2. do not water the leaves. If it rains, keep the suspect plant out of the rain… water only the media.
3. finally ensure all debris is removed from the entire surface of the tree and media. Be scrupulous about plant hygiene before it becomes an issue.

Black spot often can occurs on older leaves. Removing suspect leaves is first step. Do not compost these leaves. Put in solid waste bin.

We do not do preventative spraying with haz chems for fungus here. However a 3% H2O2 diluted 1:1 with water spray will destroy fungus and bacteria. End products of 3% H2O2 are 02, H2O and a small amount of heat . Spray in daylight so the leaves can dry before nightfall..

If black spot actually attacks and is not manageable, one might see if Bonide Revitalize Biofungicide is available in your area. It is sprayed safe for organic gardening.

Of the hazardous chemicals mentioned above, Flutriful is the safest bet. Here is the SDS. Please wear all recommended safety clothing and PPE.

By the way Infuse is reported to be a suspected mutagen, so if in fact you do get ahold of this product, please use extreme care in application and storage. .

cheers
DSD sends

 

[ACooke]

Fantastic. Thanks DSD.
I’ve only had it for ~2 months so it’s possible it was present before i purchased it; although it’s also been unusually humid here. Regardless of the cause, the above is very helpful going forward.
Thanks again.