Haven't had any problems with mine yet. Apparently, according to the net for a non chemical treatment, people are just using a strong water blast to the leaves to continually knock them off which seems to work for some. I assume you'd do this at least once a day although I don't know how I feel about this treatment when it could introduce more issues with the leaves being wet all the time.
I also have seen this recipe for a home made spray. Understand that the original author is not using this on hop plants.
Cut&Paste from the interwebs:
[b][i]GP TEA recipe:
3 cloves of garlic
2 habanero peppers
Place the garlic and peppers n a blender and add about 2 cups of water. blend until the peppers and garlic are thouroghly crushed and pulverized. If necessary add water to keep the mix liquid. After this, strain the liquid to remove the solids. Add enough water to this liquid to make 1 gallon of concentrate. Of this concentrate, use 1/4 cup per gallon of water in your sprayer.
I have heard that this mix is not good for some beneficial bugs, but I have seen no definitive proof of this ( ihave looked in many organic gardening books). Maybe somene else out here can help with this. It will definitely take care of thrips, mites, and aphids, and some ants (spray it on the mound and they sure move in a hurry)[/i][/b]
I will probably start with this recipe if and when I begin to have problems.
Good luck and may many mites fall at your feet.