Are you struggling with spider mites on your trees this Fall? If the answer is yes, then you are not alone! Spider mites thrive in hot, dry conditions, like the summer we just had, and they will more heavily impact stressed out trees.
USU’s new Arthropod Diagnostician and Urban IPM Associate, Zach Schumm, recommends that spider mites this late in the year often respond best to cultural practices instead of pesticides. He recommends that if there are still leaves on the tree, blasting the leaves with a hose will kill or disperse most of them off the tree. Mites migrate from the leaves to the branches and trunk for the winter, so if this is done a couple of times per week until all the leaves have fallen, the surviving overwintering population will be much smaller.
Removing the grass under the canopy and above the root zone of your trees and replacing it with mulch is another great way to prevent spider mites. Grass around a tree can take up all of the water before it can reach the tree roots. This extra competition for water can worsen drought stress, and stressed trees are more attractive to spider mites. Turf is also a great source of spider mites, so removing it underneath trees minimizes the chance that mites will find your trees.