I have been taught that rain can splash fungus spores from the ground up onto the plant/leaves. So preventing splash is good. My understanding is that once an "infection" sets in, it is "too late". So I am going to recommend spray before the rain, hopefully enough in advance that is get absorbed/dried before the rain can wash it off.

Newspaper and/or mulch under the plan helps minimize splash. I did this for the first time this year, and I'm going to cover a wider (do a better job) area next year. Also, removing some of the lower leaves close to the ground may help some (as the plant grows, but do not over-do it). If the lower leaves are "infected" is would be good to remove them if possible. I am beginning to think that tomatoes (plants) are a difficult to grow. But my tomatoes (fruit) sure look great so far this year.

thanks, claydirt,

I couldn't help myself - I let about 50 volunteers (out of many hundreds) survive in my garden and have been battling early blight and probably several other fungi since early in the season.

I did do my homework, though - my tomatoes are well mulched with straw and I have been vigilant, probably too much so, in removing the spotty leaves.

But I'm curious about what the bacteria do once they hit the leaves. Will the rain wash them off, or can they hang on somehow and be the front line against the rain-exploded fungus?