Diagnosing mite problems in tomatoes

Zsofia Szendrei<szendrei@msu.edu>, Michigan State University Department of Entomology - June 17, 2026

Learn how to distinguish tomato russet mite, broad mite and twospotted spider mite damage using key field symptoms, scouting techniques and management considerations.

A black/bronzed leaf from a tomato plant affected by tomato russet mite and a healthy green leaf. Photo by Zack Hayden, MSU.

Mites are among the most difficult arthropod pests to diagnose because they are often too small to see without magnification. Mites are primarily a problem in greenhouses and high tunnels, but in hot summers, they can become problematic in the field. However, characteristic plant symptoms can help distinguish among the most common mite pests affecting field, greenhouse and high tunnel tomatoes (Table 1).

The most important way to manage mites is to avoid unnecessary broad-spectrum insecticide applications that kill off their natural enemies. It is also important to avoid stressing the plants, which can happen when plants are drought-stressed. Eliminating weedy hosts from the vicinity of the crop that can harbor mites is also crucial. Not growing vegetables and ornamental plants in the same greenhouse can also help reduce mite problems.

A tomato plant with dying leaves — Broad mite feeding on tomato causing bronzing of leaves, leaving green veins. Photo by University of Maryland Extension.

Miticides should not be used preventatively, so scout regularly since many of the miticides need to be applied as soon as mites are first noticed to be effective. Once miticides are used, the mode of action groups will need to be rotated because insecticide resistance can be a problem with mites (Table 2). Thorough coverage of leaves, especially the underside, is important.

Some good sources of further information are this article from Kentucky Pest News focusing on greenhouse and tunnel mite management, and this table from University of Maryland Extension that summarizes insecticides and miticides labeled for use in greenhouse vegetables. Also, check out this bulletin on greenhouse insect pest management by Jeremy Jubenville with Michigan State University Extension for 2026 greenhouse insect management guidelines.

Green tomato leaves with white specks. — Leaf symptoms of spider mite damage, notice the stippling. Photo by Ric Bessin, University of Kentucky Entomology

When using beneficial predatory mites, miticides should generally be avoided. However, there are some chemistries that are relatively more gentle on predatory mite populations. Use the Koppert One and BioBest Side Effects app to reference these relationships.

Table 1. Comparison of mite symptoms in tomatoes.

Symptom	Tomato Russet Mite	Broad Mite	Two-Spotted Spider Mite
Scientific name	Aculops lycopersici	Polyphagotarsonemus latus	Tetranychus urticae
Where damage begins	Lower leaves and stems	Newest growth and terminals	Lower or stressed leaves
Leaf symptoms	Yellowing, bronzing, drying, curling, defoliation	Twisted, distorted, thickened, cupped leaves	Fine white or yellow stippling that progresses to bronzing
Stem symptoms	Distinctive greasy bronze or russet coloration	Distortion of new growth	Rare
Fruit symptoms	Russeting, bronzing, cracking, roughened fruit	Corky patches, deformation, cracking	Indirect effects from plant stress
Webbing	No	No	Often present
Visibility of mites	Requires hand lens or microscope	Requires microscope	Sometimes visible with hand lens
Typical conditions	Hot, dry weather	Warm greenhouse/high tunnel conditions	Hot, dry weather
Diagnostic clue	Bronzed stems and upward progression from plant base	Severe distortion of newest growth	Stippling plus webbing
Scouting tips	Examine lower stems and leaves for bronzing and upward progression of symptoms. Use a 10–20× hand lens.	Focus on terminal growth and newly expanded leaves. Look for distortion, cupping, and thickened foliage.	Inspect leaf undersides for stippling, mites, and webbing. Shake leaves over white paper to detect mites.

Table 2. A list of miticides for use in tomatoes. Tomatoes are often, but not always, grouped under “Fruiting vegetables” on labels. Read the label for more details on how to use these products, there are many restrictions about the number of applications per season. Download a printer-friendly version of this table.

Commercial name	Active ingredient	IRAC group	Pre-harvest interval (day)	Comments
Agri-Mek	abamectin	6	1 (for commercially grown greenhouse tomatoes), otherwise 7 days	russet and spider mite; field grown and greenhouse tomatoes
Gladiator	abamectin+ zeta-cypermethrin	6+3A	7	russet and spider mites; implied use in greenhouses
Kanemite	acequinocyl	20B	1	broad and spider mite; field grown and greenhouse tomatoes
Acramite/Floramite	bifenazate	20D	3	spider mites; Floramite for greenhouse and Acramite for field use
Piston	chlorfenapyr	13	1	spider mites, broad mites; greenhouse use only
Nealta/Sultan	cyflumetofen	25	1 for commercially grown greenhouse tomatoes, otherwise 3 days	spider mites only; Nealta for field and Sultan for greenhouse use
TetraSan	etoxazole	10B	1	spider mites; greenhouse use only
Portal/Akari	fenpyroximate	21A	1	controls many species of mites; Akari for greenhouse and Portal for field use
Onager	hexythiazox	10A	1	only greenhouse tomatoes, only spider mites, max. 1 application/year
Vykenda/Incipio	isocycloseram	30	1	broad and spider mites; Vykenda for retail plants and Incipio for commercial field-grown tomatoes
Movento	spirotetramat	23	1	controls broad, russet mites; suppresses spider mites; implied use in greenhouses
Oberon	spiromesifen	23	1	broad, russet and spider mites; implied use in greenhouses
Sanmite	pyridaben	21A	2	spider mites, broad mites; greenhouse use only

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