Spider Mites

by Paula
(Oklahoma, USA)

Q. Year after year I struggle with with these pests. Would it help to pre-treat tomato plants with a fish oil, sesame oil, and castor oil mix work?

A. Spider mites pierce leaves and feed on plant sap, beginning on leaves’ undersides. They work from the lower part of the plant to upper leaves. Small wounds on plants that look like white specks tell you that spider mites have been hard at work. If left unchecked, affected leaves develop a bronze or gray color, turn brown, and fall off. Spider mites also leave their signature webbing strung between plant parts or beneath leaves. They are active year-round.

How to control spider mites

Spider mites are difficult to control and have stumped many a tomato gardener. With a life cycle of 1-2 weeks in optimum conditions, spider mites multiply rapidly and feed continuously. Identify and control spider mites quickly to prevent them from spreading through your entire tomato crop.

• Spray plants regularly with a jet stream of water to dislodge spider mites.
  
• Apply horticultural oil (like neem oil) to control spider mites. Oils are only effective when wet, so repeat applications at systematic intervals to eliminate a colony.
  
• Insecticidal soaps are considered to be only marginally effective on spider mites. Like neem and other horticultural oils, insecticidal soaps such as
  Safer® Soap, work on pests when wet. Apply them repeatedly to eliminate spider mites.
  
• Commercial and greenhouse growers have had consistent success controlling spider mites with avermectin, a natural product derived from soil microorganisms and the active ingredient in Avid and Floramite.