Weez,

If it is black rot, and you've been spraying every 7-10 days then
throw the spray you've been using in the garbage. Like Bill said, Nova
is the way to go. Also Ferbam is probably good against black rot BUT
you need to get the real stuff. I won't buy anything at the local
nursery or home depot. It's not the same as getting the real stuff
from a commercial chemical supply store and mixing it yourself. BTW
FWIW ,I don't think it's black rot. The lesions aren't circular
enough. Get a magnifing glass or look real close and see if you can
see small black dots in circular form on the orange part. If there are
it's black rot. How many leaves are infected? It's possible you burned
the leaves with too strong or too frequent fungicide sprays.


Bob

"William Frazier" > wrote in message >...
> Weez wrote "Are you sure about the black spot? I was hoping I beat it this
> year! I've
> > been using fruit plus (ferbam and something else) every 7-10 days. The
> vines
> > are Marechal Foch. Weather has been cool and humidity has been staying
> > mostly under 50%, rain once or twice a week mostly at night...
> > Louise)"
>
> Louise - I'm not sure it's black rot but it sure looks like what I have in
> the vineyard. The other grape growers in our Cellarmaster club say it's
> black rot. Also, it looks like the black rot picture #21 in the Compendium
> of Grape Diseases. And from the 2004 Missouri Commercial Grape Pest
> Management Guide..."Leaves: tan spots develop with small black pustules,
> concentric with the lesion margin..." Here, in the Kansas City area, we've
> had lots of rain and black rot is showing up in vineyards. I have some in
> most of the varieties I grow and I follow a rigorous spray program.
>
> The Missouri literature says ferbam will not prevent disease development if
> applied after the fungus has infected the fruit or leaves. If you don't
> have any grape infection yet sounds like your spray program is pretty
> effective even though you see some leaf involvement.
>
> I use Nova in combination with Mancozeb and will shift to Nova/Captan
> starting this week. You might consider Nova if you problem gets worse.
> Nova offers some protection that Ferban, Mancozeb and Captan can not offer.
> Also, it is said to have some curative action if applied within three days
> of infection.
>
> I used to grow Leon Millot (cousin of Foch) and always had a good crop so
> the small amount of black rot you have probably won't kill your crop. Your
> grapes should turn red any time now and then black rot will no longer be a
> propblem.
>
> Bill Frazier
> Olathe, Kansas USA