What chemical insecticide to give in the roots of the tree? The tree is fast losing its leaves. The leaves had come one month back only.
Treat the tree with neem oil. It is both a fungicide and a pesticide and works systemically, so it will get into the whole tree and kill pests from within the tree itself. Here is more information: https://www.gardeningknowhow.com/problems/pests/neem-oil-uses.htm
I have a project this year to plant a mahogany trees in our area, I hope you can help me or give me some great idea
The general consensus seems to be about 15 feet for spacing.
These articles will offer more information on the tree:
https://www.gardeningknowhow.com/ornamental/trees/mahogany/information-on-mahogany-trees.htm
https://www.gardeningknowhow.com/ornamental/trees/mahogany/mahogany-seed-propagation.htm
Can they grow in Galveston County, Texas? Also, if so where can i get seeds besides under a tree?
You are in hardiness zone 9 and those trees are hardy in zones 10 and 11. You could try it with winter protection and see how it does. You can mail order seeds from a reputable seed catalog company. (I would discourage buying from individuals. We hear from many disappointed folks who write in and say they only received a weed.) A Florida nursery or catalog may have them since they are popular in Florida.
These articles should help.
https://www.gardeningknowhow.com/ornamental/trees/mahogany/mahogany-seed-propagation.htm
https://www.gardeningknowhow.com/ornamental/trees/mahogany/information-on-mahogany-trees.htm