Would the following around the base of each tree be applicable?

Marigolds – deter ants

Comfrey – soil enhancer (can be harvested for sprays or mulched in for the next year)

Lemon balm – deters most bugs like flies and fruit flies. Harvestable

Rosemary – decent bug deterrent. Harvestable

Lemon Geranium – colourful and effective.

If gohpers and ground squirrels are abundant, have you noticed a certain time of year (hot, cold, wet, dry) they are more abundant? Is there a certain time of year or weather condition that they tend to do more damage. I have found that if I can figure out what they are in need of, they leave most of the farm alone. In the spring they go after all my dandelions and different weeds, in the heat of the summer, if I have water around for the other animals, I find they never go after my roots. The same works for deer, in the heat of the summer when they are eating leaves, I have found that leaving water available cuts down on the deer damage as they are just thirsty.

Covercrop – the more diversity the better.

Some food for thought 🙂