Question
Dear Sir,

We have a Japanese Maple for about 8 yrs and its been in good health all this time but recently in the last month we have noticed a wet sticky substance on about 30% of he leaves and its got us puzzled, we have 4 plants but this is the only one with this problem can you advise please, we live in the north east of England.

Kind Regards,

Ken.

Answer
Sounds like this tree has not done this "dripping" before. Since the dripping is sticky--I think you have an insect infestation. There are insects that suck the juices from from leaves or the small twigs and secrete as awaste product a substance called honeydew. Honeydew is a substance made up of water and sugars and will fell sticky. Normally a black sooty mold will grow on this honeydew making the tree leaves have a black color on thier surface. There are two insects that fit this discription--aphids and scales. Aphids are small insects that suck the juice from leaves and if you look closely you can see them on the leaves and if they are touched they will move. Scale insects also suck juices from leaves but also will suck juices from small twigs. Scale insects live inside a shell covering resembleing a tiny turtle shell and do not move when touched. Aphids are easily killed with an insecticide spray. Scales also can be killed with sprays but since they are under the shell it takes more presistance and a different type of insecticde.

I would treat the tree with an insecticide called Bayer Advanced Tree and Shrub Insect Control. This is applied around the tree to the soil and the roots will transport the product to the twigs , branches and leaves. And when the insect sucks the plant juice it will be killed. Check with your local nursery fro this product.
Here is a link to more information on this product. You can get it ata akocal nrusery type store If you can not it can be orderd on line at http://www.domyownpestcontrol.com/bayer-advanced-12-month-tree-shrub-insect-cont
I do not know if they ship to your country.

https://www.bayeradvanced.com/find-a-product/tree-shrub-care/12-month-tree-shrub-insect-control-landscape-formula