Friday, August 2, 2013

Russet Mites found on Tomato

Recently, russet mites were discovered associated with injury on a tomato sample at the U of I Plant Clinic.  This is not a common pest found in Illinois, but serves as a reminder that we should be careful when diagnosing all plant problems.

Russet mites can be a very tiny pest of tomatoes and other plants. So tiny in fact, they can easily go without being noticed on plants and still be causing damage. They can be found in almost all areas where tomatoes are grown.  They are only about .2mm long, and if populations are high, they are capable of causing serious injury on tomatoes. Damage first becomes apparent in mid-summer when plants are half to fully grown and injury will generally start at the base, then move throughout the canopy. The highest population of mites will tend to be found where the damage is visible. A high infestation will cause leaves to start to curl and turn a russet brown color as the mites feed, sucking the juices out of any green part of the plant. Hot weather is conducive for high mite populations, and in turn, plants can even be defoliated. More information on russet mites can be found at: 
(Information gathered by Nick Pudhomme, U of I Plant Clinic student worker)

The russet mites on this tomato sample was discovered at the Plant Clinic by examining the leaves showing symptoms under magnification:

This pest was featured in the latest Illinois Fruit and Vegetable News (IFVN) found at the following link:

Dr. Richard Weinzeirl, U of I Extension Fruit and Vegetable Entomologist stated the following about the russet mite: "Tomato russet mite is smaller than two-spotted spider mite and is somewhat wedge- or cigar-shaped.  The sample came from a home garden in northern Illinois, and the tomatoes were adjacent to petunias (often associated with russet mites), but it served as reminder to point out that most miticides are not very effective for russet mite control.  Agri-mek and wettable sulfur are generally most effective against this pest."

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