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Re: [nafex] kaolin clay

This is a page from the May 19, '00 Apple Pest Management bulletin as issued
by Glen Koehler of the University of Maine Cooperative Extension (Pest
Management Office).  Glen maintains a terrific IPM site and more that can be
accessed at > http://pmo.umext.maine.edu/apple/applpage.htm.  Hope this helps.
>                                                                          PESTICIDE NEWS
>                                                                                      Surround vs. bulk kaolin clay 
>                                                                                                  Surround is a registered EPA pesticide for use on
>                                                                                      apples that has also been cleared by the Organic Materials
>                                                                                      Review Institute.  Applying a series of Surround sprays has
>                                                                                      been found to provide about 80% reduction of plum
>                                                                                      curculio damage compared to untreated trees.  This is not
>                                                                                      quite as good as the 90+ % control achieved with the
>                                                                                      standard treatments of Imidan or Guthion, but it isn't far
>                                                                                      off.  Surround may be seen as a supplement for existing
>                                                                                      controls, and may be sufficient as a replacement for
>                                                                                      organophosphate insecticides where there is moderate to
>                                                                                      low plum curculio pressure, or where the desire for
>                                                                                      organophosphate avoidance and/or organic certification
>                                                                                      outweighs the difference in efficacy.
>                         Surround seems to reduce tree stress from high temperatures and also to promote red fruit color
>             development even from early season applications.  Later season applications can prevent apple maggot
>             damage.  Surround is relatively benign on predators and is neutral on mites in that it does not reduce the
>             mite population but does not cause mite population increase either.
>                         As with any material, there are requirements for effective use.  Surround works as a barrier film. 
>             Excellent coverage is a must.  For plum curculio, the first application should be made right at Petal Fall,
>             with a follow-up application no more than a week later.  It takes two applications to establish the level of
>             residue and coverage required for full efficacy.  Continued protection through the plum curculio
>             immigration period would require reapplication at 7-10 day intervals.  Because the Surround doesn't kill
>             the plum curculio that encounter it, protection might be required for a longer period than the 3 to 5 week
>             protection period required with organophosphate insecticide.
>                         The label for Surround states that the composition is 95% kaolin clay.  Kaolin clay is sold in bulk
>             form for many uses such as papermaking and pottery.  Therefore, one might be inclined to think it is
>             possible to save some money by purchasing cheaper bulk kaolin clay instead of paying for the same
>             material labeled as Surround.  However, the kaolin clay in Surround and the kaolin clay sold for other uses
>             are really different materials using the same name.  
>                         Here is some of what I learned from recent conversations with Dr. Michael Glenn of the USDA
>             Agricultural Research Service, who recently received an award for being the lead scientist behind the
>             development of Surround for use as an apple pesticide, and also with John Mosko the technical rep for
>             the manufacturer:
>                         The kaolin clay in Surround has been highly processed through several manufacturing steps to
>             achieve specific particle size, shape, density and texture that are much different from bulk kaolin clay. 
>             These attributes are essential to the way Surround functions.  
>                         Efficacy:  The finished product is hydrophilic instead of hydrophobic, and the mean particle size
>             of Surround is much smaller than bulk kaolin clay, and just as importantly, the range of particle sizes is
>             narrowed.  Particle size makes all the difference in how the particles affect insects.  Larger particles don't
>             work.  Surround has even shown promise as a suppressant against fire blight bacteria. 
>                          Phytotoxicity:  Researchers have investigated kaolin clay since the 1930s as a foliar spray
>             material, and have always had to contend with phytotoxicity.  Bulk kaolin clay particles reflect the
>             photosynthetically active radiation (i.e. light) required by leaves to make food for the tree.  Home-brew
>             concoctions of bulk kaolin clay can and have caused serious phytotoxicity on tree fruit and vegetable
>             crops by starving the foliage of light.  By controlling size, shape and porosity of the particles, Surround
>             particles allow light rays within the range needed for photosynthesis to scatter and bounce their way
>             down to the foliar surface.  Photosynthetic performance is not degraded, and by reflecting some of the
>             other heat generating wavelengths, the plant's physiology can be enhanced rather than impaired.
>                          Residue:  Surround is engineered for the right balance between retention to provide residual
>             control, and depletion so that the coating even from late season applications is gone by the time fruit is
>             harvested.  Surround particle lay on the waxy fruit cuticle without becoming embedded in it.  Bulk kaolin
>             clay can become embedded into the cuticle making it difficult or impossible to remove.
>                         Formulation and coverage:  Standard spreaders designed for apple pesticide tankmixes are
>             designed to spread pesticides used at rates of no more than about 6 pounds of wettable powder or dry
>             flowable per acre.  Surround is applied to apple trees at rates of 25 to 75 pounds per acre.  The sheer
>             volume of dry material that is to be spread requires different surfactant characteristics.
>                         As in much of life, you get what you pay for, and the deal that sounds too good to be true
>             probably is.  The only good news about bulk kaolin as a spray material is that even though bulk kaolin
>             does not have an EPA label, the Maine Board of Pesticides Control does not consider application to
>             apple trees a violation if it is being used for non-pesticidal reasons.  And that is about what you get with
>             bulk kaolin clay: a non-pesticide that poses risk of phytotoxicity, irremovable residue, and maybe clogged
>             nozzles thrown in for no extra charge.  
>                         The Pesticides Control board does consider it clearly illegal for anyone to sell a material that does
>             not have an EPA label, such as bulk kaolin clay, for use as a pesticide.  Just because bulk kaolin clay is
>             about as natural as you can get, that doesn't make it safe for plants or applicators.  One of the main
>             reasons for EPA registration is to prevent the sale of products that pose unreasonable hazard to crops
>             and applicators.
>             Sincerely,
>              Glen W. Koehler, Associate Scientist IPM/NAPIAP 
>                         Where brand names for chemicals are mentioned, no endorsement is implied nor is discrimination intended
>             against products with similar ingredients.  Consult pesticide product labels for rates, application instructions, and safety
>             precautions.  The label is the law.  Disregard any statements in this newsletter if they appear to contradict label
>             instructions.  Users of pesticide products assume all associated risks.
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>             of Maine System shall not discriminate on the grounds of race, color, religion, sex, sexual orientation, national origin or
>             citizenship status, age, disability, or veterans status in employment, education, and all other areas of the University. 
>             Questions and complaints about discrimination in any area of the University should be directed to the Director of Equal
>             Employment Opportunity, 101 North Stevens, (207) 581-1226.

edforest55@hotmail.com wrote:
> I seem to recall a thread many months back on the use of kaolin clay
> as a pest deterrent on fruit trees. I searched the archives under
> kaolin but could not find anything. Any hints?
> kevin b

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