I like the way you think! But Anthracnose is completely different
http://www.sactorose.org/rosebug/iro...tm#ANTHRACNOSE
something is eating the leaves. If not leafhoppers then it is a mystery
insect?
I have several roses with the same problem!!.

Note: On the same page as above, the leafhopper damage is not the same?

Dieter L Pietryka
Owner/Photographer
Blitz World Enterprises


http://www.blitzworld.com/



"elsie" wrote in message
oups.com...

wrote:
I have 3 knock-out roses that are about 4 years old. Each year they
have been great except this year. The leaves have developed white spots
which seem to be turning into voids. I looked closely for bugs, mold,
or something (on both sides of leaves). But I can not see anything
alarming. Does anyone have an idea? BTW, I have 3 different knock-outs
in front of the house doing great!

In your email you mention that you get white "spots" on the leaves
which turn into voids. (I'm gathering by voids you mean holes?) If they
are definite circular spots, then they couldn't be leafhoppers, as
these insects leave a pale stippling/blotching/mottled effect on
leaves, not definite holes.see
http://pep.wsu.edu/hortsense/scripts...ableName=plant.
Also, you mention that you have looked closely for bugs on both sides
of the leaves. If there were leafhoppers, there would be evidence of
them on the underside of the leaf (where they suck the sap) and you
would notice them jumping and flying when disturbed, (they are about
4mm long, are greenish/yellow and have red eyes - they look like tiny
cicadas), also there would be evidence of their tiny sticky brown
droppings, which are difficult to remove. Plus you'd see evidence of
their cast skins on the undersides of the leaf. Have a good look on the
undersurface of the leaves for any of these tell-tale signs. If there's
no evidence to suggest these insects, I'd say the voids are caused by
some kind of fungus. Maybe anthracnose, though the spots usually start
off as brown and then turn white in the centre while rest of leaf
remains green. These spots then drop out of leaf giving it a shot-hole
appearance.(could these be the voids you mentioned?) If this is the
case, you'd need to spray with an appropriate fungicide. Your local
nursery should be able to help you find the correct one to use for this
disease. Also try improving the air circulation around the plant and
make sure that it has at least 6-8 hours of sun a day. Hope this helps.
Regards Elsie