"Clotton" Leaf Killer

Janice M. Glime jmglime at MTU.EDU
Sun Dec 6 16:59:05 EST 1998

This sounds like cottony scale, an insect that "cultures" fungi on its
back and raises its young in the protection of the fungal mass.  It works
well against predators, presumably, because they, like you, they cannot
recognize it as an insect.  One method that seems to help is to put Safers
on the plants.  You should be able to order it through your local nursery. 
It is so-named because it is harmful only to the insects and other such
small creatures that breath through pores or spiracles on their surface. 
It is in reality a solution of Ivory soap, but you can just mix your own. 
There are at least six formulas of Ivory soap throughout the country, and
only one is safe for the plants.  The principle is that the soap
interferes with the surface tension/cohesion of the water, enabling it to
penetrate the spiracles and suffocate the insects. 
 Janice M. Glime, Professor  
 Department of Biological Sciences
 Michigan Technological University
 Houghton, MI 49931-1295
 jmglime at mtu.edu
 FAX 906-487-3167 

> I know very little about house plants but I enjoy house plants and have a
> "plant room" in my house.  For several years I have been fighting some kind
> of a "cotton" substance that forms on my plants.  It forms in small (maybe
> about the size of the "o on this page") spots on the leaves and stems of my
> plants.  It's a very delicate substance.  If you are careful you can kind of
> knock it off into your hand.  If you touch it or try to pick it up it
> basically disintegrates.  I will form on either the upper or lower side of
> the leaf and on the stems.  It doesn't appear to be insect related but more
> of a cotton type growth.
> I have been fighting this stuff by wiping the leaves.
> Does anyone know what this is and how to prevent it's return?
> Thanks for you help,
> Dave

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