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Neem Oil on a Chinese Elm?

Hello-

I bought a Chinese Elm about two (2) months ago. I keep it outside on my deck. I expected its leaves to yellow and drop when I first got it (which is what happened).

After an initial leaf yellowing/dropping the tree greened up again and looked healthy. Over the past few weeks I have noticed more yellowing leaves. The yellowing seems to start off in one spot & then spread out over a leaf. I suspect this is from some sort of insect, but I do not know. I've seen flying insects scatter from my Chinese Elm when I water it or pick off yellow leaves.

I've read that systematic insecticides are bad for Chinese Elms and should not be used on them. Does anyone know if neem oil could be used on Chinese Elms, or will it damage them?

Thank you for your help.

Jason

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Jason,

Look carefully at the leaves and tender shoots for black lesions. Chinese Elms are susceptible to a fungal disease known as 'Black Spot' This starts with a yellowing and then a small dark spot which spreads to cover leaves and then proceeds backwards to the petiole and, if not checked, eventually twigs. I fight this every year and this year, with the cool, damp conditions, is no exception.

To answer your specific question, I have not used Neem Oil on mine so I can't say.

Norm

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bonsaiboy
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Neem oil should be completely safe. There is a thread somewhere here on this website that talks about neem oil; I'll try to find it.
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Thank you Norm & Bonsaiboy!

I do see some dark lesions on the leaf, so I believe it could be "Black Spot". What should I do to combat "Black Spot"? I've been picking off the leaves that exhibit yellowing or drying-out symptoms.

Also, today I noticed a few lady bugs on my chinese elms when I was watering my tree. I will look for the thread on Neem Oil. I have not found it yet.

Norm- please let me know what you do to combat Black Spot.

Thanks again.

Jason

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Jason,

The first thing you should realize about this disease is that it cannot be treated, only prevented. In other words the leaves that are affected will not recover and will, if allowed to remain, spread the infection. The best ways to combat Black Spot fungus on Chinese Elms is to prevent it in the first place.

This fungus thrives/spreads during humid weather and effects new foliage to a greater extent than mature foliage, so I never mist Chinese Elms that are outside. I have even gone so far as to shelter them from rain. Again, this is more important early in the year when tender, new foliage is present.

Next, you must remove any and all effected leaves or the next time the foliage gets wet it will spread. Be assiduous in this as any infected leaves will later spread the spores and reinfect the plant. Make sure to remove all effected foliage from the surface of the soil or surrounding area. If the infection has spread deeper, into actual shoots, prune back beyond the infected area. I have not seen this fungus go past this stage, of effecting tender shoots, but I believe it is possible.

Lastly there are fungicides available that do work but again, they are not curative but preventative. My usual method is to remove the effected foliage, as above, and then treat with the fungicidal spray. I have a product in mind but it goes against the overall philosophy of this site. There are several organic remedies that may work but I cannot vouch for their efficacy with this fungus. Copper based sprays are one traditional treatment for fungus in general and I have seen mention of milk based solutions referred to here in the past, but I have not used these personally. Perhaps next year I will experiment with a more environmentally friendly product.


Norm

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bonsaiboy
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Here is the thread: https://www.helpfulgardener.com/forum/viewtopic.php?t=925
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Thanks again Bonsaiboy & Norm-

I took all of the yellowing leaves off of my chinese elm and will shelter it from the rain. I was misting my chinese elms as I thought that the leaves were drying out. I will stop doing that immediately.

I took a photo of infected leaves next to green/healthy leaves. That photo is right here:

https://img200.imageshack.us/i/bonsai002.jpg/

As you can see, there are dark markings on the leaf in the middle on the left-hand side. I pulled off some leaves similar to that one. Does it look like Black Spot fungus to you?

I've also taken a photo of my chinese elm. It is here:

https://img200.imageshack.us/i/bonsai003.jpg/

It was painful to work on my chinese elm today. I took off many yellow leaves and am worried that my tree will get killed by this fungus. I will search for Daconil and begin using that in an attempt to prevent further fungal outbreaks.

Please let me know your thoughts on all of this.

Thank you again.

Jason

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To me it almost looks like the leafs are yellowing from being overwatered. Chinese Elms like the soil surface to go dry before being watered agin.
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I apologize for the multiple posts . . .

What about making my chinese elm an indoor plant? I figure the drop in humidity would help to prevent additional fungal outbreaks. We have 50% humiditty in my area right now.

Would this be feasible, or would bringing my chinese elm indoors just subject my poor tree to additional shock? I don't want to subject my chinese elm to unecessary shock, but that might be the lesser of two evils right now, no?

Will Black Spot fungus kill my entire tree if left unchecked? I guess the only remedy is to remove infected leaves as they occur and take steps to prevent additional fungal outbreaks? What happens if all of the leaves on my chinese elm get hit with this fungus . . . I mean I'd have to remove all of the foliage from my tree if this happened, right?

Jason

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Bonsaiboy-

Thank you for the response.

That may be another tack I take with this tree. Over-watering is a possibility that I had not thought of. I water all of my trees using the toothpick/wooden skewer method. I stick the toothpick/skewer into the soil to determine if it is dry lower down in the soil.

I do not water the tree unless no soil sticks to the toothpick/skewer. Moreover, it has been in the mid-80's to mid-90's where I live, so I've been watering my trees more often lately.

Are you suggesting holding off on watering my chinese elm a little bit longer? I may do that. I'll hold off on watering it as much as my other trees (3 junipers, a pine, a serissa & 3 ficus + 2 jades I water about once a week).

Thanks again.

Jason

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Jason,

The pictures you have shown do not seem to exhibit the typical symptoms of Black Spot. I'm sorry if I alarmed you unnecessarily. I checked my plants in an attempt to provide a picture but it seems my treatment is working and I do not have an example at the moment. I just picked my last round of leaves a few weeks ago and all seems OK right now.

Norm

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Hello again-

My Chinese Elm is still getting more yellow/brown leaves. I have noticed some ants and other insects I suspect may be doing damage to my tree. I plan on taking three approaches.

First, I am going to use cinnamon to repel the ants. Second, I am going to use Neem Oil to repel any other insects.

Finally, I am going to alter my watering practices. I have noticed that the soil does not seem to drain quickly enough for my Chinese Elm. I believe it is retaining water longer than it should, which may be leading to over-watering by me.

Does anyone have any thoughts on watering it? Should I water it less often? Also, has anyone heard of cinnamon having any negative effects on trees?

Thanks.

Jason

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Jason,
I have noticed some ants and other insects I suspect may be doing damage to my tree.
Whenever I see Ants I always look closely for the presence of Aphids. These insects have formed a symbiosis and are often found together. I believe I have read that Ants also 'farm' Scale insects but I have never seen this personally.
I am going to alter my watering practices. I have noticed that the soil does not seem to drain quickly enough for my Chinese Elm. I believe it is retaining water longer than it should, which may be leading to over-watering by me.
I have allowed the soil of Chinese Elms to become pretty dry at times and have never noticed any problems. Obviously there is a limit to this so take care not to allow the foliage to wilt. Try allowing an extra day before watering while carefully observing the tree.

I think you are on the right track. Be aware that peat based potting mixes are known to be difficult to re-wet so when you do water do so thoroughly and repeatedly. This ensures that the soil is properly saturated. Don't water a little, often, water a lot, at appropriate intervals. Try the skewer/chopstick method outlined [url=https://www.helpfulgardener.com/forum/viewtopic.php?t=1479]here.[/url]

Begin reading about bonsai soils and re-potting if you have not already, start [url=https://www.helpfulgardener.com/forum/viewtopic.php?t=3422]here.[/url]

Norm

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Thank you Gnome/Norm!

I will let you know how my Chinese Elm responds. I'll wait a month or so & post a photo. I sprayed it with neem oil last night and put cinamon on the surface of the soil to repel ants.

I had to pick alot of yellow/brown leaves off of my Chinese Elm over the past few weeks, so there are alot of bare spots on it. It has a few (4-6) new leaves sprouting out. Should I expect any more new leaves or will I have to wait until the spring?

Thanks again.

Jason

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Jason,

It is still early enough in the season that I would expect that, if things are well, you should see a new flush of growth before fall. Chinese Elms, being sub-tropical, actually seem to grow later into the season than true deciduous trees.

Norm

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Its me again:

My Chinese elm is still getting yellow leaves at an alarming rate. I've used neem oil & cinnamon on it to repel aphids & ants. I've even stopped watering it as much the past few weeks.

I'm really starting to suspect that the problem is that my tree is either root-bound or the soil composition is so bad that water is being trapped, thereby causing "overwatering".

What about a repot? I know that the poor tree is going through a lot, but I believe I have determined what is causing the chinese elm's leaves to yellow and fall off.

I've read in a few places that it is ok to repot a chinese elm in the fall. Please let me know your thoughts on this.

Thank you.

Jason

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Jason,

It is possible to re-pot Chinese Elms in the fall after a brief dormancy. I would only suggest that if you intend to bring it inside for the winter, this would likely entail supplemental lighting. If you are going to allow it a full dormancy you are better off re-potting in the spring.

I have also re-potted one in the summer and it responded well for me. It was definitely something of a risk but it turned out OK. Unless you are prepared with enough new medium on hand there is little point in re-potting it into another poor medium.

The soil in your picture looks OK, unless what I see is simply a top-dressing. There is not a solid, glued in place, top-dressing is there?

Norm

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Norm-

The top layer consists of pebble that was placed there for appearance by the online retailer. The pebbles were not glued down (otherwise I would have taken them off immediately), rather they were spread across the surface for appearance.

Below the pebbles is a dark, thick, and compact soil. It is very slow draining and has stayed pretty damp for the past three days after a watering. I have not taken the tree out of the pot to see if it is root-bound since I wanted to avoid shocking it further.

I have akadema, and "bonsai soil" which I plan on mixing together to make a decent medium. I think that combination will be a better draining mix than what I have right now. The tree is losing leaves at a rapid rate and I fear leaving it as is will kill it off all-together.

Here is a picture of the tree as I bought it:

https://img176.imageshack.us/img176/1969/apr1310.jpg

This is a picture of the tree about two weeks ago:

https://img200.imageshack.us/i/bonsai003.jpg/

As you can see it has lost a good deal of its foliage. Even more foliage has been lost since I took the picture a few weeks ago, and I am not getting many new foliage. I understand the repot is risky, but I feel leaving it as-is will be an even riskier proposition.

Please let me know if you have any thoughts, pointers, or reservations. I'm keeping my fingers crossed & hope that all of this effort is not in vain.

Thank you so much for your help.

Jason

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Thank you for your help Gnome & Bonsaiboy. I'm almost positive my Chinese Elm has very poor draining soil. I've altered my wattering routine to account for the soil.

My Chinese Elm has scores of new leaves budding out right now. I"m going to wait until this fall after the leaves drop to repot it in better soil. Then I'm going to bring it inside for the winter.

Thanks again!

Jason

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