Tell your neighbor that you have severe allergies and are really stressed out about all the spores,pollen,mold,dust,chemicals that are coming off her garden and that you would appreciate it if she would remove it.
Since you are up the hill all of these contaminants will travel into your yard and home by natural convection currents.
If she has a compose bin that too must be removed.
I would also tell her that you do not want her using any fertilizers as you are also allergic to any chemical product.
I would inform her of your concern regarding all the nasty little creatures that a garden can attract,such as bugs,worms,moles,mite infested birds,disease carrying squirrels,chipmunks,racoon's,possum's and the large rat's you saw in her yard that probably are harvesting all kinds of disease if not the plague itself.
you may want to go to a pet store and purchase a few dead ones that they use to feed to snakes and throw them in her yard the night before before you mention this and then go hysterical when you see them in her yard the next morning.
At this time you might want to mention your severely allergic reaction to any bee sting.
Yellow Jacket's,Hornet's,Bumble bee's,Honey bee's oh My....
Yellow Jackets,Hornet,Bumble bees,Honey bees oh My................
Yes a garden is something you do not want next to your living quarters.
You have no allergic reaction to concrete and would appreciate it if she removed the garden and installed concrete instead.
If this doesn't work you could always tell her that she should mind her own flippin business,install a very high fence and buzz off!