Ken Anderson wrote:

> "Brad B." > wrote in message
>>
>> My understanding is that Mancozeb is a preventive and will not kill an
>> existing infection.
>>
>>
> If that's true, then the Mancozeb needs to be on the plant when and if a
> spore
> lands on it. Once it's washed off, it would have zero effectiveness.
> Sounds believeable to me.
> Ken

I believe Mancozeb - Penncozeb will ramain to some extent after a rain. A
lot depends on the amount of rain and the length of time it rains. I
believe that if the fungicide is on for several hours prior to a rain, some
of it will remain after a light rain. You might just look at the leaves
after a rain and see if there is any spray residue on them. My
understanding also is that Mancozeb - Penncozeb will not kill an existing
infection. You will need a systemic fungicide to do this and they are
expensive. Prevention is the best route.