Oleander toxicity and fruit trees
I removed an oleander bush that had a root ball which was about two feet in diameter. Not all of the roots were excised. I would like to plant a dwarf fruit tree in the three foot diameter hole. Can the fruit collect the toxin from the residual oleander roots and should I be concerned?
I am not all that familiar with oleander, however, it's my understanding that oleander is very poisonous. Most of what you read concerns the above ground parts being poisonous, even dried plant parts. There's not much in the literature regarding roots (although much literature says 'all plant parts' are poisonous...when they elaborate, they never mention roots).
Here's my take: a newly planted fruit tree should not be allowed to bear until year 3. By that time, I would hope that most of the roots would be decayed or certainly in the process. By that time, it would be hard to guess how much of the toxin is present or where it is. According to http://www.inchem.org/documents/pims/plant/pim366.htm#SubSectionTitle:3.3.2%20%20Description,%20chem..., the toxin is insoluble in water. Therefore, not much of it (if any) would enter the roots of another plant growing nearby.
I would plant the fruit trees and enjoy the fruit in year 3. Hope this is helpful.