does fungicide kill on contact?
As always start by carefully reading the label.
Then follow it.
This is not just a recommendation. The label is the law.
The deal with fungicides is that they prevent the infection they don't
Depends on the fungicide and the extent of the infection. All the
fungicides I can think of will kill spores on contact, and if the spores
have germinated and invaded the plant, some fungicides will kill them
too. However, if the fungus has really gotten a hold on the plant you
need a systemic fungicide to cure it. Systemic fungicides are not
recommended on plants which produce food (or more precisely, eating the
plant products from a plant on which systemic pesticides have been used
is not recommended).