I have a rather large Parasol plant, which lately has a sticky almost sap-like substance on the leaves. I've also noticed very small, flat, hard, brown things on some of the leaves, which I can wipe off. There are also brown bumps on the stems of the plant as well. The plant is also losing leaves. Any thoughts on what is wrong with my plant and how to fix it?
It is scale. This article will help you:
How do I care for this plant over the winter?
Parasol plant? Scheffleras are commonly known as umbrella plant or umbrella tree, so that might be what you have. But also, there is currently being marketed a plant known as Mandevilla sun parasol, or parasol pink mandevilla. Is this what you have? If so, these are not indoor plants, although since they're tropicals they can't take a northern winter. You might try letting it go dormant - keep it in a spot protected from freezing temps (basements are often used) and water very sparingly. like once a month. It will quickly lose all its leaves, but when you put it back outside in the spring and start watering it fully, it should come back.
This article will answer your questions: https://www.gardeningknowhow.com/houseplants/schefflera/schefflera-plant-care.htm
I have Parasol palm about 4ft in 10 liter pot here in India in March summer days. I water day after day, but from 5 days ago I forgot watering, and the result is leaves are drooping and shrinking, not yellowing and not brown. Only shrinks and droops. Is this major problem? How can I save it?
A Parasol Palm can be located in a partial sun location.
You can resume watering and see if the palm can recover from the lack of moisture.
Your palm should have moist soil and high humidity.
I have a Chinese Parasol fully-grown tree; however we built a pool, and the concrete decking will be poured around the tree. Tell me about the roots affecting the concrete.
Being a semi-large, and invasive, tree it will be best not to surround the tree with concrete. Concrete will likely crack, and the tree can suffer from root suffocation.
I would recommend removing the tree before pouring concrete.
Here is an article to help you kill the tree, should you need to do so: