Wasps will not go near another wasp nest for fear of mass defensive attack. So why not hang On your apple trees a non toxic faux wasp nest...of the kind that look like a paper Chinese lantern as a deterrent. You can make these or if there are children around they can make them for you. Here's how...go to your local craft store and find the bagged paper mâché ready to mix and a bag of large pear shaped balloons. You can also make your own paper mâché from news paper which is really good because the color will be very close to a natural wasp nest color. Blow up your balloons and totally cover them with a few layers of the mashe. Allow to completely dry and then take a pin and punture the ballon inside. Make a hanging loop with needle and thread and hang two on each tree on either side. This is the only non toxic way to handle this problem.

or you can hang out a wasp trap , google lots to choose from

We used to half fill a jam jar with water, leaving enough jam in the jar to tempt them. Then hang it on the tree. You can often buy the imitation nests Loosestrife mentioned from those little catalogues we are always getting in the post.