Spider mites are one of the most common pests threatening our trees and shrubs. And you probably aren’t thinking about spider mites until your tree shows signs of infestation.
Here are the answers to a few common questions about recognizing and treating spider mites on your beloved oxygen-giving friends.
What trees are susceptible to spider mite infestation?
Though all trees are susceptible to spider mite infestation, the following species are common hosts:
- Elms
- Evergreens
- Fruit trees
- Honeylocust
- Maples
- Mountain ash
- Oaks
- Roses
Spider mites attack plans suffering from drought, so you should be on your highest alert for these pests during the hottest, driest parts of the year.
What do spider mites look like?
Spider mites are tiny, eight-legged arachnids closely related to ticks. They can be red, brown, yellow, green, translucent and are hard to see unless you’re up close to the bottoms of leaves where they like to hang out.
What are the signs of a spider mite infestation?
More visible than the spiders themselves are the clues they leave behind. Leaf drop or yellow, orange, brown, or gray spots on your tree’s leaves may be the first signs of infestation from far away.
At a closer look, you’ll see fine webbing under and around the leaves and other parts of the plant. If you want to get even closer, you may be able to visually confirm the presence of the tiny pests.
How do spider mites kill trees?
Spider mites may be able to kill small trees and shrubs entirely but usually only wound or damage mature trees. They do this by feeding on the chlorophyll of the plant, typically in the leaves or needles.
How do I control a spider mite infestation?
Treatment of spider mites should commence at the first signs of infestation. The longer you wait, the harder it will be to control. There are water, biological, organic and chemical controls you can use to prevent or stop spider mite infestation.
Water Control
Because spider mites prey on drought-stressed trees, making sure yours are watered properly will be your first line of defense. Smaller trees can be strongly hosed periodically to remove mites and their webs, making to sure hit both sides of the leaves or needles.
Biological Control
Spider mites do have natural predators, some of which you can purchase and apply to affected trees. Garden supply stores will be able to recommend the specific type of predatory mite you need. Refrain from using chemicals in your garden to encourage these species to control the mites naturally.
Organic Control
A few tablespoons of natural soap like Dr. Bronner’s Pure Castile soap diluted in a quart of water creates an organic spray that can control and wash spider mites away. If that doesn’t work, horticultural oils and insecticidal soaps you purchase from your local garden center may do the trick.
Chemical Control
Chemical treatment of spider mite infestation should be a last resort. Some arachnicides or miticides will attack both the spider mites and the beneficial, predatory species and make the problem reoccur or spread to other plants.
