This is just my private theory, no science behind it.

I suspect that the pest and disease problems are greatly magnified by neighbors who decide to plant a garden, plant fruit trees, plant whatever, and then lose interest and let it go to the bugs.

They provide a nursery for the propagation of all sorts of bugs and disease.

If everybody had their bugs and diseases under control, they'd either be wiped out or at least very greatly reduced.

I've got a neighbor 2 houses over who has all of his trees absolutely infested with tent worm. I can see them from my house it is so bad. He does nothing, and every year I fight the battle with the tent worm.

If he'd get rid of his tent worms, and I don't allow tent worms, where would the new crop come from? They wouldn't have any place to breed.

Another neighbor abandoned his fruit orchard. It gets no care. His apple trees provide a breeding ground for coddling moth. He and I have the only apple trees for 3 miles around.

I don't allow coddling moth to breed on my property. If he'd get rid of his coddling moth, they wouldn't have any place to breed.

As I drive around town, I always see lots of veggie plots that were started and then allowed to go to weed. The plants look sick and ill cared for. They are growing bugs and mildew and virus that will blow on the wind over to the nice garden a couple of houses down.

So, in answer to your question, you can help the disease and pest problem by keeping your garden healthy and well cared for. But you will never eliminate it because you have control of too small an area.

Very good info...except tent caterpillars hatch in the spring. What you are seeing on your neighbors trees is fall webworm. I know..nitpicking but they are different pests. Fall webworm is only defoliating what the trees will lose soon anyway but it is nasty looking.

westfurd just keep treating your garden with the most organic and least toxic to the beneficials and you will do ok.