Winter months are an excellent time to prune fruit and nut trees. Naked and dormant, it is easy to see each tree’s structure. This is also a good time to inspect for common pests, such as scale insects and European red mites.
While you will certainly want to get rid of any San Jose scale, walnut scale, Italian pear scale, or frosted scale insects you see, you should leave the European red mites where they are.
Why in the world would you want to leave pests on your trees?
Females measure in at 1/72 inch. Males are 1/80 inch, which means you could line up 4 of them on the edge of a dime.
Females can lay eggs without mating, but these offspring will all be male. [This is called arrhenotokous parthenogenesis. Most parthenogenic offspring are female, as with aphids, so this is different.]
Heavy feeding can bronze leaves. Bronzing may be fine for baby shoes, but it makes photosynthesis impossible.
Whereas other mites produce webbing and cause leaf drop, the European red mite produces little or no webbing and no leaf drop.
Persistent, heavy mite feeding can also cause transpiration burn (leaf blackening), reduced fruit size and quality, shoot growth, trunk and limb growth, and root growth.
If populations of European red mites become significant, you can apply delayed dormant horticultural oil, but that oil may cause sunburn damage. It’s a tough call. Since European red mites have demonstrated resistance to miticides (a type of pesticide geared toward mites), it is better to avoid chemical sprays. Spraying these pests with a hose does nothing.
If your garden or landscape has a lot of biodiversity, odds are pretty good that there will be enough predators to control European red mite populations. Also, keeping plants dust-free makes the environment less hospitable to these pests.
You can grow a surprising amount of food in your own yard. Ask me how!