help identify disease please.

Ross Koning koning at ECSUC.CTSTATEU.EDU
Mon Apr 14 12:10:06 EST 1997


And yet another possible cause is leaf-miners.
These tunnel between the upper and lower epidermal
layers eating the mesophyll.  This results in
patches and connecting tunnels that appear white
because the mesophyll is gone.  The black dots
could be the miners themselves in-between the
epidermal layers.

Again, more description would be needed to help
identify what you have and how to proceed.  Are
the white patches smooth on the exterior or are
they "fuzzy?" Are the patches purely external
or are they internal to the leaf?  Do they appear
white when viewed from both the upper and lower
surfaces of the leaves, or only from just one
view?  Etc.

ross

At 10:44 AM -0400 4/14/97, Diane Karasevicz wrote:
>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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