Soil mites are tiny arthropods that live in the top layers of soil. While most soil mites are harmless or beneficial to gardens, large populations can damage plants. If you have an overabundance of soil mites, there are several effective ways to control their numbers.
What Are Soil Mites?
Soil mites belong to the arachnid family and are distant relatives of spiders. There are over 10,000 identified species of soil mites. Most species are microscopic, measuring 0.25-0.40 mm in length. They have eight legs and rounded bodies.
These mites live in the top 2-3 inches of soil, leaf litter, and under the bark of trees. They feast on decaying organic matter, fungi, and bacteria. Some species are predatory and eat other tiny soil organisms.
Soil mites play an important role in breaking down organic materials and releasing nutrients back into the soil. They aerate the soil with their movement and tunneling. At normal population levels, they do not damage plant roots or leaves.
When Do Soil Mites Become a Problem?
Large infestations of soil mites can overwhelm plants and damage roots, leaves, and stems. Signs of a severe soil mite infestation include:
Visible webbing on soil surface
Speckled or stippling damage on leaves
Distorted leaf growth
Wilting or death of seedlings
Stunted plant growth
Excessive moisture and high organic matter content can cause soil mite numbers to explode. Their populations boom in spring when conditions are ideal for reproduction.
Certain types of mites, like the cyclamen mite and broad mite, directly attack plants and can destroy crops. Other mites vector plant diseases.
Effective Ways to Control Soil Mites
If you notice signs of excessive soil mites, take action right away to get the critters under control. Here are some smart ways to reduce their numbers:
Remove Leaf Litter and Debris
Clear any dead leaves, straw mulch, wood, or garden debris from the soil surface. This takes away habitat and food sources for mites.
Let Soil Dry Out
Soil mites thrive in perpetually moist conditions. Allow the top few inches of soil to dry out completely between waterings. This reduces the habitat suitability for mites.
Mix in Sand
Adding a gritty substance like horticulture sand or perlite creates an inhospitable environment for mites. It helps to dry out and aerate the soil. Mix in a 25% ratio of sand to soil.
Apply Diatomaceous Earth
Sprinkle diatomaceous earth atop the soil. The microscopic, sharp edges of this powder scratch the waxy cuticle of mites and causes them to dry out. Apply a reapplication after watering.
Use Neem Oil Sprays
Neem oil extracts disrupt the life cycle and reproduction of mites when sprayed on the soil. Mix neem oil with water according to label directions and apply liberally to affected garden areas.
Introduce Predatory Mites
Predatory mites like hypoaspis miles and various nematodes hunt and consume plant-parasitic mites. Releasing them into your garden helps naturally lower soil mite populations.
Solarize the Soil
Solarizing uses the sun’s heat to kill pests in the top few inches of soil. Cover moist soil with clear plastic and leave it in hot sun for 4-6 weeks. High temperatures destroy most mites, eggs, and larvae.
Rotating between different plant families each season denies mites a continuous food source and disrupts their life cycle.
Grow Repellant Plants
Some plants like marigolds, chrysanthemums, and garlic naturally repel soil mites with the chemical compounds they release from roots. Interplant these around more vulnerable crops.
Prevent Future Soil Mite Outbreaks
Once you get a soil mite infestation under control, take proactive steps to prevent further flare-ups:
Avoid excessive moisture and ensure soil dries adequately between waterings
Eliminate weeds and clear out plant debris
Mix in sand for better soil drainage
Use drip irrigation instead of overhead watering
Let soil rest with cover crops or mulch between crop rotations
Keep a close eye on plants for early signs of mites like leaf stippling. Take quick action at the first signs of damage to keep soil mite populations at bay. A vigilant prevention approach is key to protecting your garden from these tiny pests.