§      Broad mite showing up in greenhouses now
§      Medallion^® applications on zonal geranium
§      Will you pass an MDA/EPA WPS compliance check?

Broad mite showing up in greenhouses now
Dave Smitley,
Entomology and
Thomas Dudek, MSU Extension Horticulture Agent

This past week we have had several cases of broad mite damage to New Guinea impatiens, ipomea, thunbergia, and gerbera. Broad mites are closely related to cyclamen mites. Plants most likely to have broad mites are peppers, dahlia, zinnia, chrysanthemum, and numerous perennials, but they are occasionally found on many other plants.

Broad mites are tiny, white or clear mites, only half the size of spider mites (0.1 to 0.3 mm). They are difficult to see without a microscope. Broad mites feed on the undersides of leaves and in new flower and leaf buds and shoots. Leaves and flowers usually turn brown or black where they have been feeding. Infested leaves may also be cracked or curled. They reproduce rapidly, completing a life cycle in four to five days in warm weather. Broad mites require high relative humidity for their survival. Damage is usually first noticed as a disfiguration, cupping, curling, or browning of new shoots, terminals or edges of leaves.  The distorted leaves can be very hard in texture compared to a normal leaf. If broad mites are found, infested plants can be treated with Floramite or Avid. The new growth taking place after a miticide treatment should be healthy.

Medallion^® applications on zonal geranium
Matthew Blanchard and Erik Runkle
Horticulture

Medallion 50WP (fludioxonil) fungicide is often recommended on geraniums for control of certain foliar and soil borne diseases such as aerial blight (Rhizoctonia spp.), alternaria leaf spot (Alternaria spp.), fusarium stem and root rot (Fusarium spp.), and rhizoctonia stem and root rot (Rhizoctonia spp.).  In 2003, a few greenhouse growers expressed concerns on the sensitivity of some geranium cultivars when Medallion 50WP was applied.  Growers observed stunting and chlorosis on some cultivars following drench applications.  We performed an experiment with three application methods and three rates of Medallion 50WP on zonal geranium to document potential phytotoxicity resulting from these applications.

Rooted cuttings of zonal geranium 'Blues 2001' and 'Tango' were transplanted into 5-inch square pots filled with a commercial soiless medium on July 8, 2003. Plants were grown at 68°F under a natural photoperiod and treated with Medallion 50WP using one of three application methods:

1)    Drench application -- solution was applied to wet all of the growing media.
2)    Spray application -- solution was applied as a foliar spray to runoff.
3)    Irrigation application -- solution was applied as a combination drench and spray.

Application protocol for Pelargonium 'Blues 2001' and Tango^® violet

Plant foliage was visually evaluated for symptoms of phytotoxicity 7 and 14 days after applications using a scale of 1 to 3 (1=severe, 2=moderate, 3=no visual damage).  A visual root evaluation was conducted on October 2, 2003, 13 days after second application using a scale of 1 to 3 (1=small root mass with or without brown roots, 2=moderate stunting and browning, 3=large mass of white roots).  Photographs of plants from each treatment were taken concurrently with visual evaluations. 

Medallion applied as an irrigation application resulted in the greatest phytotoxicity with all concentration rates as compared with other application methods.  Drench applications resulted in moderate symptoms of phytotoxicity at all application rates.  The control treatment displayed no symptoms of phytotoxicity and served as a comparison for the three application methods and rates. 

A correlation was seen on plants with severe symptoms of phytotoxicity and the amount of root stunting.  For example, on zonal geranium 'Blues 2001,' 4 oz. irrigation treatment with severe visual foliar damage also displayed moderate root stunting (Figure 3).  Differences between the two cultivars were observed on drench and irrigation treatments.  The drench treatment caused more phytotoxicity on Tango^® violet, while phytotoxicity from the irrigation application treatment was more severe on 'Blues 2001.'

These results indicate that Medallion 50WP applied twice as an irrigation treatment (contact with foliage and roots) causes phytoxicity on the two cultivars tested.  Foliar spray and soil drench applications may cause stunting or chlorosis on some cultivars of zonal geraniums at higher rates.  Syngenta Professional Products Corp., the manufacturer of Medallion 50WP, has recently revised the label and removed geranium from the list of plants on which Medallion has been tested and found to be safe.  Syngenta has stated that due to the lower tolerance of geranium to misapplication and higher use rates, this label change was necessary.  The label now includes a warning statement and a recommendation for testing Medallion on a small number of plants to evaluate for any possible phytotoxicity before proceeding with widespread use. 

The revised EPA approved label for Medallion 50WP can be found at: http://www.syngentacropprotection-us.com/pdf/labels/SCP769BL1B0303.pdf

Will you pass an MDA/EPA WPS compliance check?
Jeanne Himmelein
Extension Horticultural Agent

Can you believe it's been 12 years since we learned about the Federal Worker Protection Standard?  You were trained a few years ago about what you needed to do, what your facility requires, and what your employees need to know to meet the mandatory requirements with this federal law. As I've been in the greenhouses this spring, I've noticed that some of you have made some changes to your facility and the Central Notification Documents are missing or parts of them are not there.  I then ask myself, myself, "Do you think the handlers have reviewed the handler training book lately? Are treated areas being properly posted? Are pesticide applications being properly documented?  Have all of the employees completed the pesticide safety training?"

I thought it was time to remind you of the importance of WPS and to make sure you and your employees are following the law since MDA is out checking facilities for compliance and rumor has it that they may be fining greenhouses that are not compliant. I would hate for you to not be in compliance and be fined. 

Here is a checklist (in pdf) of requirements for you to print and do a mini compliance evaluation yourself. 

If you need to replace documents or training tools, Gemplers (http://www.gemplers.com/ or 800-382-8473) has the documents needed for central posting, training booklets, training flip charts, worker, handler and trainers notebooks and the signs for posting areas that are not to be entered. Society of American Florists (SAF) has the training video as well as the booklets.  You can check their web site for ordering information at: http://www.safnow.org/ or call (800) 336-4743 for a catalog.  

If you have questions, feel free to contact your MSU Extension Agent, we will be more than happy to help you.