How To Count Your Orchard Mites

I'm susan Allen with the Fruit Grower Report. There are good and bad mites in apple orchards, the bad mites damages foliage and good mites eat bad mites. They are known as pest mites and predatory mites and in a recent talk Dr. Tara Baugher from Penn State Integrated Pest Management Program, tells us how to check our trees for both. By the way this is good info for home gardeners as well.

A quick way of determining mite levels in your orchards is to use a magnified hand lense or a head piece magnifier to determine the percentage of mite infested leaves. Select ten trees in the orchard on the most susceptible variety and count ten spur leaves from each tree for the presence or absence of mites to determine the mite threshold level. As a general rule in apples a spray threshold of only 2.5 mites per leaf exists early season before June. The threshold increases to 5 mites per leaf from June through mid july. Use a threshold level of 7.5 mites per leaf for the rest of the season. If the mites per leaf do not reach these levels no control action needs to be taken Orchards with stable populations of stable t pyri never reach these thresholds as longs as there are at least long as there is at least one predatory for every 10 pestmites per leaf. Mite management is important because mites feed on leaves and cause injury to the tree by removing leaf tissue, resulting in premature fruit drop.