help identify disease please.

Diane Karasevicz dmk8 at CORNELL.EDU
Mon Apr 14 09:44:08 EST 1997


ANOTHER possible cause of the white patches is a disease called powdery
mildew. There is a record of it occuring on passion flower, at least in
California. It may occur elsewhere, too, if I dug more into the literature
(where are you located???. The black beads could be the sexual stage of the
fungus (Erisyphe sp.); the whitish growth would be the asexual stage. 

If you have access to a compound microscope, put some of the black beads
onto a microscope slide in some water and squash the dots. Inside there
should be sacks containing spores (should be visible at 100 - 400x). The
black beads also will have some long hairs coming off their sides when
viewed under a microscope.

I really can't give control recommendations without knowing for sure what
the problem is and where you live. Contact your local Cooperative Extension
office for more help.

Diane

Plant Disease Diagnostic Lab
Cornell Univ.
Ithaca, NY


**************************************************************************
At 04:23 AM 4/14/97 -0700, you wrote:
>On 12 Apr 1997, Daryl wrote:
>
>> I am growing passion flower but its becoming plaged with little white patches
>> that if I look closely at with a magnifying glass, I can see tiny little
black 
>> beads.  What are they.  I have used diazinon but that tends to kill the
leaves 
>> also. 
>> 
>> Could someone identify this?
>> 
>> Thanks
>> Daryl
>
>******************************************************************************
>Daryl,
>
>Without actually seeing a diseases leaf, I'd say that you probably have a
>spider mite infestion.  The white patches would be caused by the piercing,
>sucking feeding activity, and the tiny black beads would be the excrement
>of the mites.  Again, this is without actually seeing.
>
>I'd try malthion with some sort of sticking agent mixed in.  Follow label
>directions.
>
>Tim
>
>
>
>




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