"Franz Heymann" wrote:

Hello Franz

concerns. There are "greener" versions, which IIRC, are
mostly based on urea.

FH I believe that diesel oil (paraffin, domestic heating oil)
FH cannot be absorbed by plants via root-hairs, but when it is
FH inserted via a hole bored in the stump, it kills it
FH effectively. Please tell me if I am wrong.

Kinda. They won't take oil in through the roots as such. Oil is
lighter than water and although osmosis means it won't absorb it as it
would water (differential salt content [1]), it /does/ clog up the
pores and effectively kills the tree through thirst.

I've seen several substantial trees die from even very small leaks on
domestic oil tanks over a period of time, and one - a 80+ evergreen
oak that had died all up one side from a tiny tiny drip from an oil-
line running alongside.

Actually drilling holes and putting it into the heartwood is liable to
preserve rather than rot, I'd have thought?

--
[1] Blimey, I really did pick something up from those interminably
dull horticultural lectures!

Simon Avery, Dartmoor, UK Ý http://www.digdilem.org/