Watch for broad mite symptoms


Broad mite, Polyphagotarsonemus latus (Banks), has reared its ugly little head on a sample of English ivy which was examined by Nancy Taylor at the C. Wayne Ellett Plant and Pest Diagnostic Clinic at Ohio State University.  The grower explained that the plants were not growing and that the youngest leaves had been very stunted for a number of weeks. Nutritional testing had not revealed any problems; bromine being added to the irrigation water was suspected as a toxin but the grower did want the plants evaluated for evidence of a disease or insect problem.

Stunted and distorted new growth on English ivy caused by cyclamen mite

Stunted and distorted new growth on English ivy caused by broad mite
English ivy showing shortened internodes and stunted, curled foliage caused by cyclamen mite injury

English ivy showing shortened internodes and stunted, curled foliage caused by broad mite injury

The symptoms did, indeed, mimic a chemical injury but a very close look at the youngest leaves which were still emerging and expanding from the buds showed numerous eggs, nymphs and adult broad mites. These pests were responsible for the foliar distortion. Broad mites are tiny and very high magnification is required in order to see them, unlike other types of mites such as the more familiar two-spotted spider mite which shows up in greenhouses occasionally.

Broad mite eggs (L) and the mite itself (R) among leaf hairs.


Broad mite eggs on pepper. Adults are below circle. The eggs are characteristic of the broad mite.

The grower reports that effective management practices for broad mite are contributing to the English ivy’s good recovery.

If you suspect a broad mite problem but do not have sufficient magnification to see them, samples can be submitted to the Clinic.  See the Clinic’s web site at


Description: adults are very small,  light brown to light yellow in color, and they are difficult to see. Adult females can lay up to 76 eggs. Males live for 5-9 days, females 8-13 days.

Eggs are very characteristic, they are translucent with little white dots on top (wax-like domes).

Plants affected: English ivy, begonia, cyclamen, new guinea impatiens, African violet, ageratum, azalea, dahlia, gerbera, gloxinia, jasmine, lantana marigold, verbena, zinnia. Other plants include: citrus, tomato and pepper.


One way to manage broad mites is through the use of miticides. The list below includes some products that have been labeled for use against broad mites on ornamentals.

Pylon (chlorfenapyr)

Avid (abamectin)

Sanmite (pyridaben)

Judo (spiromesifen)

Ultra-Fine Oil (horticultural oil)

M-Pede (potassium salts of fatty acids)

Note: Remember to read and follow the recommendations of all product labels before using any product. The listing of a product does not imply endorsement by the authors.

Biological control: the predatory mite Neoseiulus californicus has been reported as a good predator of this mite.


Nancy J. Taylor
Program Director
C. Wayne Ellett Plant & Pest Diagnostic Clinic
Ohio State University, 8995 E. Main St., Bldg. 23, Reynoldsburg, OH 43068-3399
614-292-5006 Office / 614-403-1640 Mobile / 614-466-9754 Fax

Luis Cañas, Ph. D.
Associate Professor, Insect Ecology in Controlled Environments
Dept. of Entomology
The Ohio State University
Ohio Agricultural Research and Development Center
1680 Madison Ave.
Wooster, Ohio  44691
Phone: 330-263-3818, Fax: 330-263-3686

Plant Diagnostic Sample Submission App

New to Ohio State University’s C. Wayne Ellett Plant and Pest Diagnostic Clinic is an app for iPhone or iPad which will allow Clinic clientele to submit images of their plant or insect problem either as stand-alone samples or to supplement a physical sample being sent to the Clinic.

OSU’s Clinic joined with 7 university-based plant diagnostic laboratories in the development of the app which is available for free from the i-Tunes Store and can be found here: or by scanning the QR code. Anyone may download and use the app which will guide the users with questions customized for various situations including greenhouse and nursery production. The Clinic will charge its  basic exam fee for digital samples submitted through the app (

While pictures are worth a thousand words they do not always tell the whole story. Some plant disease or insect samples will still require microscopic examination or other types of specialized tests to confirm the diagnosis. If a physical sample is required as a follow-up to a digital sample the Clinic’s basic exam fee will not be charged for that physical sample.

Universities/labs partnering in the development of the Plant Diagnostic Sample Submission app are:
• Alabama Cooperative Extension System
• University of Connecticut Plant Diagnostic Laboratory
• University of Illinois Extension
• University of Kentucky Plant Disease Diagnostic Laboratory (County ANR/HORT Agents only)
• Michigan State University Diagnostic Services Laboratory
• University of New Hampshire Cooperative Extension Plant Diagnostic Lab (UNHCE Field & State Specialists only)
• Ohio State University C. Wayne Ellett Plant and Pest Diagnostic Clinic
• Purdue University Plant and Pest Diagnostic Laboratory


Sending Plant Samples for Diagnosis

Issues are always cropping up with our greenhouse crops – whether they be nutritional, disease, insect or cultural in nature!   In order to make informed decisions on how to manage and treat the issues at hand, proper diagnosis is essential.  Growers in Ohio can send plant and insect samples directly to the OSU C. Wayne Ellett Plant and Pest Diagnostic Clinic.  The clinic website has detailed information on the best ways to prepare and send your samples to ensure they arrive in good condition for examination and possible testing.

General recommendations for greenhouse samples from the clinic include:

  • Samples should be fresh.
  • Samples should represent the early to middle stages of the problem.  A  completely dead and decaying sample cannot be reliably diagnosed.
  • Samples should be carefully packaged and shipped early in the week to avoid  weekend layovers during which the sample will deteriorate.
  • Be sure to include sample documentation and background information.  The  specimen form can be downloaded on the website.
  • Pictures of the problem in the field are always helpful.  The environmental  conditions of the plant can play an important role in the  diagnosis.

If you have questions, please feel free to contact the clinic at :

Phone: 614-292-5006
Fax: 614-466-9754
web site: