Getting Rid of Spider Mites
Reoccurring mites can be a big problem and a big headache, so I sympathize with your frustrations. And not to add to your frustrations, but during my research on this problem to make sure I got you the best and most thorough solution, I read that depending on how the insecticide carbaryl (sevin) is being used, it can actually compound and add to the spider mite population! I know, just what you wanted to hear.
I have two recommendations that I believe will resolve your problem. The first and foremost at this time of the season, is to switch to a spray containing Neem Oil. It probably won't be called that on the shelf, but the product containing that as an "active ingredient" is what you want to use. It's totally organic, and is classified as an insecticide, miticide and fungicide all in one, so it's a great product. You should be able to find it at your local independent nursery or garden center, but you'll probably need to ask for it. I believe it'll be under the Fertilome label at the nursery, or possibly the Safer label at the garden center.
I did not read this, but from personnel experience (and common sense), be sure to wear protective clothing when you apply the spray. An old long sleeve shirt, some coveralls or an old pair of jeans should do the trick. I say this because of two challenges you'll face. One is, the majority of the spider mite population resides on the under side of the leaves, so as best as possible, you'll need to get beneath the foliage on your trees and spray in an upward motion. Secondly, you'll discover very quickly Neem Oil doesn't exactly have a pleasant odor, so even as hard as you try, you're apt to pick up some actual over spray or at least some drift, and I guarantee, that odor will stick with you for a while. So wearing protective gloves and/or a mask or hat would also be a good idea. I'm not trying to paint a "doomsday" picture for you here, it's just from personnel experience I'm trying to forewarn you, so you don't come back to us shaking your finger, rightly so. Neem Oil is the only spray I'll use in my own yard.
Obviously, follow label directions closely, and read any warnings. Spray while it's cool, early morning would be best, and when the wind is not blowing (and if you have them, try to keep your chickens out of the area at least until the spray, and over spray, has had a chance to dry). At least one more application before the heat of summer arrives would be beneficial. That should carry you through the remainder of the growing season. If you still see an infestation after summer, go ahead with a fall application.
Now to the second recommendation. All stone fruits require what's called a "dormant oil" application during the winter time while the trees are "dormant". Spider Mite's eggs actually overwinter and are ready to populate your trees as soon as the warm weather arrives! Volck Oil is a common product for this, or simply a product called Dormant Oil/Spray (what a coincidence!). This one is also classified as an "organic product", so please try to schedule at least two applications during the winter time, again following label directions closely.
I know this all sounds like a lot of work, but I believe after this year, following these guidelines, you should have your mite problem well under control. And just think of those delicious peaches and apples down the road!
NOTE: The above recommendation in it's entirety, applies only to your "stone fruits", those that lose their leaves and go dormant during the winter. The portion containing the use of Neem Oil would apply to your Orange tree, or any other evergreen fruit tree you may have.
Monthly To-Do: March | #SpiderMites