stop tree roots into veg garden

[opalred]

i have a bad tree growing next door and the tree roots are amazing

i have put down sheet plastic under the garden twice

a few months the tree roots find away in 

you can have a pin hole and the root will go through and multiply to a thick branch 

is there a poison to put under plastic cheers

 

[cooked]

Old engine oil might do it but you will be polluting groundwater and your garden big time. Why not dig over twice a year along the boundary? 

[drtreelove]

There are some considerations advisable for controlling roots from a neighboring tree.  ( - Based on my experience as an urban forestry specialist and former municipal arborist, where these issues of invasive roots are almost a daily exercise in neighbor diplomacy and tree ownership legalities and lawsuits, as well as arboriculture.)

 

• First is to consider if the base of the tree is on private or public property, and the owners may have their own concerns. Will your efforts at root control for your own garden be a detriment to the health, stability and survival of a valued tree for the neighbors? 
• By cutting roots, installing a barrier, or chemically limiting the natural growth of absorbing roots and anchor roots, will you be harming the physiology or destabilizing a large tree and creating risk for your own or neighboring property.
• As Cooked indicates, chemicals can have a negative environmental impact that goes far beyond your intentions, including to your own garden. 
• Can you relocate your garden to a more favorable spot in your property? 

That being said, a physical barrier along the property line or garden boundary is one option, This can be digging a trench and installing a subsurface ferro-cement wall, or pre-fabricated plastics composite "root barrier". Even these root barrier options may only be good for two or three years, before the roots find a way under or over or through cracks.  The more substantial the barrier, the longer it will be effective.

 

I have not seen commercial root barrier material in Thailand, but here is an example from the US; 

 

http://typargeosynthetics.com/products/root-barrier/biobarrier-root-barrier.html