Question
QUESTION: Good day,
I have a huge oak (acorn) tree in my backyard. I do not know the exact species. A few years now it started getting a shiny sticky coating on the leaves. On close inspection I found it has bright green lice on the underside of the leaves. Apart from this problem, it's has a 'fall-out' of tiny glue-ish droplets that sticks to everything and turns a horrible nasty black. My fences and walls and cars are coated in it. Is it due to the lice?

Is there an insecticide I can use to combat my problem via the roots? The tree is too big to spray and apart from that I have chickens, dogs and kids, so I do not want to use any dangerous chemicals.
Please help I am all out of ideas.
Thank you

ANSWER: Sounds like aphids --these insects will suck the plant juices from the plant and secrete a substance called honeydew which is high in sugar content and sticky. A sooty mold will grow on this sugar making the black. Control the aphids and the honeydew will go away. Treat the tree with an insecticide called Bayer Advanced Tree and Shrub Insect Control. This is applied to the soil around the tree and the roots will carry the insecticide to the leaves and stems and when the insects suck the plant juices they are killed. It will take a couple of weeks for the insecticide to get to the top leaves depending on the tree size. Here is a web link to this product check with your local nursery for this product. I do not know if it is sold in your area but should be able to contact the company and see if you can get it there. It being a liquid will not harm the animals or kids. It Should be applied in the spring and will last the whole season  

http://www.bayeradvanced.com/tree-shrub-care/products/12-month-tree-shrub-insect

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QUESTION: Thank you for the answer.
Could this 'honeydew' be the cause of air-way infections and allergies? My kids are young and suffer from these quite often so does my wife.
The tree is old and I've saved it from termites twice already, so again thank you for the answer. I would have hated to cut it down for a lack of knowledge.
According to me you are the expert of the year!
Regards

Answer
No honeydew will not effect allergies or infections. Normally a black sooty mold will grow on the high sugar honeydew and these spores could cause a problem if there is a high population of the sooty mold.

On this honeydew dry airborne black mold spores land, stick, germinate, and quickly start to grow. The mold flourishes as long as it has a continuing source of insect-supplied honeydew. Among other things, the dark mold spores on the leaves cut down on the amount of sunlight the plant can receive, and thus further robs the plant of needed food from photosynthesis.

As the mold grows and spreads it turns the infested leaves and stems a fuzzy white or a sooty looking black. The entire effect is one of dirtiness, as indeed it is. The mold quickly reproduces itself by releasing billions of microscopic-sized airborne mold spores. These spores float in the air, if they are inhaled and we are allergic to them it could possibly cause some problem. But I would doubt it. In any case, control the aphids and the black  sooty mold will go away.