From the book NEEM A tree for solving global problems, published by
National Academy Press.
Page 100, Margosan-O is an ethanolic neem extract concentrate having
3,000 ppm azadirachtin (+-10 percent) and is baed on the original process
developed by the U.S. Deptartment of Agriculture(USDA) in Beltsville,
Maryland.
While I did not find any reference IN THIS BOOK to control of the listed
Bee diseases, there are numerous references to Neem extracts (not
necessarily azadirachtin) controlling bacteria and fungal species.
Page 103 under Test 13-Bee Adult Toxicity Test.  With the assistance of
the University of California's Apiry at Riverside, California, Vikwood,
Ltd. Ordered a "Bee Adult Toxicity Test" on honeybee worker adults.
Margosan-O was administered as a direct contact chemical using field
dosages up to 4,478 ppm A.I./ha. It was found to be benign to honeybees
at well above the recommended dosage of 20 ppm (diluted, as a foliar
spray) for a common pest, the gypsy moth, Lymantria dispar (L.).
 My comment is that this material works on the younger instars of various
insects and may not have had any effect on Adult Bees but what about
brood if you treated a hive for disease or mites.
Page 14 Three new neem based products-Azatin, Turplex, and Align- have
entered the U.S. insecticide market.  The U.S. EPA has approved Align
for use on food and feed crops. Margosan-O is now registered in all 50
states and the EPA has approved it for use on food crops.
 I found no other Bee related sections in this book. There are many references c
ited so further research is necessary.
Phil Soderman [log in to unmask]
On Tue, 4 Oct 1994, Robert Rice wrote:
 
> Can anyone give me details about a product available through
> garden supply shops called Margosan-O. I would like to know what
> the composition of this material is.  I believe that it is
> suppose to control nosema and chalk brood and is a natural
> extract from a tree.
>
> Robert Rice
> CSIRO Division of Entomology
> Canberra, Australia.
>
> E-mail  [log in to unmask]
>