Oil should remain as an important tool in controlling mites, and if it does, these products will be effective for many more years. We have several highly-refined spray oils for use in tree fruit which can be used without fear of phytotoxicity. These oils have a high percentage of unsulfonated residues which make them safe for tender leaves. Vegetable oils and mineral oils have not shown themselves to be effective pest control agents and should be avoided. For European Red Mite control, oils are best applied at the tight cluster to early pink stage.
Blossom damage can occur when oils are applied at full pink in warm weather.
Oil suffocates the eggs when the eggs are most active just prior to hatching, so the closer your oil application is to egg hatch the better. How to use oils Oils work by suffocation and work because they can get into cracks and crevices where insect eggs are laid. To get the best effect from oil you must have lots of water on the tree in order to get optimal coverage. No one likes to spray dilute sprays, but for oil treatments, dilute applications will provide the best control. For example, a 400 gallon equivalent tree will be sprayed dilute with roughly 240 gallons of water at tight cluster.