Mar 24, 2016 - Like Oil & Soap

QUESTION:

What products can I apply to tomato plants in order to kill spider mites?

ANSWER:

Believe it or not, malathion, an organophosphate, is still available from hardware stores for spider mite treatment on tomato plants. I'm not sure if you're asking for your own personal tomato plants, but I don't think that's a good risk to take with a customer's tomato plants. There doesn't seem to be a great systemic miticide for tomatoes. Your best bet is probably horticultural oils and insecticidal soaps.

Horticultural oils and insecticidal soaps have mechanical modes of action. They either smother target pests and their eggs or disrupt cell membranes, respectively. Both only provide contact kill, so treatments need to coat the leaves, especially the undersides where spider mites tend to group. Multiple applications may be necessary. Under hot, sunny conditions, oils may burn plants and soaps will become ineffective as they dry out.

Two products available from Univar are Ultra-Pure? Oil and M-Pede®. M-Pede® is an insecticidal soap that is OMRI-listed for organic use.

View past Ask Mr. Pest Control questions.