Identifying and Controlling Destructive Red Spider Mites on Tomatoes

Tomatoes are a favorite summertime crop for home gardeners. However, warm conditions also bring tiny red spider mites that can quickly damage tomato plants. Learning to identify and control these nearly microscopic pests is key to preventing infestations that stunt plants and reduce yields.

Recognizing Red Spider Mites

Two common mite species attack tomato plants:

• Two-spotted spider mites – Most common Identified by two dark spots on their oval, transparent bodies Usually pale yellowish-green.

• Tomato red spider mites – Less common but also very damaging. Tiny and more red-orange in color.

Spider mites thrive in hot dry conditions. Look for the following signs of an infestation

• Yellow stippling, speckling or bronzing on leaf surfaces. Leaves turn yellow and may dry up or fall off entirely.

• Fine webbing on undersides of leaves and along stems. Webbing may completely coat plants in severe infestations.

• Specks that look like dirt on leaves but brush off to reveal moving mites underneath.

• Stunted, low-vigor plants with reduced fruit production. Plants may be killed by heavy mite feeding.

Mites are often found clustered along leaf veins on the undersides. Use a magnifying glass to inspect for mites if leaf stippling is present. Identifying them early is key before populations explode.

Preventing Spider Mite Attacks

The best defense is preventing mites from ever gaining a foothold:

• Avoid water stress – Keep tomato plants consistently watered. Drought-stressed plants are more susceptible.

• Increase air circulation – Allow ample space between plants for air to flow. Stake/trellis vines. Prune selectively.

• Control weeds – Mites feed on weeds too. Eliminate vegetation around gardens.

• Clean up debris – Remove plant residues and fallen leaves to eliminate hiding spots.

• Monitor regularly – Inspect undersides of leaves to spot mites early before they multiply.

Organic Spider Mite Controls

If mites do appear, act quickly to limit damage. Organic miticides smother and kill mites on contact:

• Insecticidal oils – Use neem, canola, soybean or cottonseed oils labeled for mite control. Coat all leaf surfaces to smother mites.

• Insecticidal soaps – Fatty acid soaps dissolve mite cuticles when sprayed directly on them.

• Sulfur – Dust sulfur powder onto plants. It burns and dehydrates mites.

• Horticultural oil – Light coats of dormant oil sprays smother eggs before they hatch.

• Strong water spray – Blast mites off plants with a strong jet of water. Repeat frequently.

Apply treatments every 5-7 days for 2-3 weeks to kill newly hatched mites. Spray undersides of leaves thoroughly. Combine methods like oils + sulfur for best control.

Rotate between different miticide classes rather than repeated applications of one product to prevent mites from developing resistance.

Using Predatory Mites

Natural predatory mites can be purchased and released onto infested plants. The beneficial mites feed on spider mites without harming plants. Two effective species are:

• Phytoseiulus persimilis – Voracious predators. Very effective for controlling two-spotted spider mites.

• Neoseiulus californicus – Feed on a wider variety of mites. Excellent for hot, dry regions.

Follow release instructions for the number of predatory mites needed per plant based on pest mite populations. Reapply beneficial mites as needed until all spider mites are under control.

Preventing Infestations Next Season

To break the seasonal cycle of mites attacking tomato plants:

• Remove all tomato debris and weeds after harvest. Dispose of infested plant material.

• Till garden beds to disrupt eggs overwintering in soil.

• Rotate plant families yearly and avoid planting tomatoes in the same location.

• Apply horticultural dormant oil spray just before new growth emerges in spring.

With preventative care and early intervention, destructive red spider mites can be controlled without harming tomato plants. Consistent monitoring and quick response keeps populations in check before they expand out of control. Protect your summer tomato harvest by getting familiar with how to identify and manage these tiny tomato pests.

Frequently Asked Questions About Red Spider Mites on Tomatoes

How do you know if spider mites are present on tomato plants?

Look for yellow stippling on upper leaf surfaces, webbing on undersides of leaves, and tiny specks that move if brushed. Use a magnifying glass to inspect for mites on both sides of leaves if symptoms appear.

What conditions promote spider mite infestations?

Hot, dry weather coupled with drought-stressed plants. Lack of airflow, dense foliage, and proximity of weeds and debris also encourage mites.

Should you spray anything preventatively for spider mites?

No sprays are necessary unless mites are already present. Oils and sulfur can be applied before problems start but may be harmful to beneficial insects. Monitor regularly and only treat if mites are found.

How often should you spray for spider mites?

Apply miticide sprays or releases of beneficial predatory mites every 5-7 days for 2-3 weeks to break the mite life cycle. Rotate between different treatment methods.

How do predatory mites control spider mites?

Purchased beneficial mites (Phytoseiulus persimilis, Neoseiulus californicus) feed on pest mites without harming plants. They naturally reduce spider mite populations once released onto infested plants.

Is it okay to use insecticidal soap and neem oil together for spider mites?

Yes, using both products together can improve control as they work in different ways. Insecticidal soap kills mites on contact while neem oil works as a repellent and anti-feedant.

Spotting and quickly controlling destructive red spider mites is key to keeping tomato plants healthy and productive through the hot summer months. Consistent scouting, early intervention, and integrating multiple organic control strategies offers the best protection against these invasive pests.