Chinese Elm with sticky leaves and white spots

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Location
Roseville, CA
USDA Zone
9b
One of my two Chinese Elms has developed, as the title says, leaves that are sticky and glossy on top, and that have white spots scattered about over the undersides and some on the top. Otherwise, the tree looks healthy. The other photos show how we have our trees on the balcony rail of our apartment. The tree with the problem is on the right.
 

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Can you or anyone here recommend a solution? It looks as if dish detergent and water spray is the most commonly used.
 
Last edited:
Can you or anyone here recommend a solution? It looks as if dish detergent and water spray is the most commonly used.
It is effective only if you keep after it. Soap will need applying frequently. There are a lot of more effective things that can be found in most Garden Centers.
 
I've been pretty lucky to not have many insect problems, ('cept scale on figs!), but I have success with this product. Yeah, it's the depot, see if any local garden centers carry before trundling of to "The Big Top"

 
Maybe some white fly on the tree too. Brush and bump the foliage. If you see white bugs flutter off the tree you have white fly in addition to aphids.

To your proposed mix, add a little cooking oil. Only spay in the evening when the sun is setting so you don’t burn the foliage. Before you spray, hose down the tree first and you will likely take care of a big percentage of the infestation.
 
I would probably stop at a big box garden center and pick up a spray with Pyrethrums in it. If you have "Rose Spray", you can use that. There are insecticide sprays for roses that work well, apply to trees while they are outside. Don't spray in the house.
 
Sevin has been used for several decades for chewing insects like beetles but is not terribly effective for sucking insects. You will probably obtain contact kill.
 
I go go with Leo on this all day. Get a product with Pyrethrums in it.
Sevin is a great product and you could get good control by contact, but it is for chewing insects. Knocks beetles down fast. I use it every year one time when Japanese beetles are active among us.
 
Pyrethrums, as stated above, will take care of your problem. If you can get a pyrethrum spray with soap and/or an oil all the better. If there is soap in a product, you will see “fatty acids” somewhere on the label.
 
It has now dropped about 5 or 6 of the affected leaves. Is that normal, or do I have more problems?
 
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