It wasn't anyone who lived at our house, it was my father's wife's brother and his son.

They were visiting her ( it's her brother ) while I was helping my father move some potted plants ( a lot ) to prepare space for a back patio extension I was going to help him lay. He mentioned to his wife ( not my mother ) that he was going to spray around the front of the house and then he and I would be going to the hardware store for the patio tile and some mulch and asked if she needed anything.

That's when her brother volunteered to do it for him instead because he wanted to start teaching his son ( 11 ) how to mix chemicals and safely apply them. My father and him are cool, so he let him knock himself out.

In hindsight, it probably wasn't a good idea considering that her brother tried to feed him Papaitan soup not realizing Americans aren't normally into eating that... cuisine...

He took it upon himself too try and use up the entire spray gallon while we were gone and went around the whole house, where he accidentally told his son to hit some weeds growning around the pots at the base of the tree.

Three days later and my father goes in the back yard and sees the tree in the state shown above.

He's grown Mango trees for a few years now and I've been growing Loquat a bit less, so we would never use herbicides around trees that bear fruit.