These conditions are worse with a lot of rain. I would cut back on the watering and perhaps using some kind of mulch to prevent splatter from the soil might help.

Some varieties are more prone to diseases compared to others. Do you see a variation of disease symptoms within your tomato plot?

chervil2: Yes, there is variation although all the plants are at least somewhat affected. The worst are the romas and Bush Goliath (a new variety for me this year). Even the Defiants, which I plant because they have blight resistance, are pretty bad. It may not be significant but the least affected are the indeterminate varieties - Gardener's Delight, Sweet Olive and Wapsipinicon Peach.

I'm alternating Daconil with copper now.

Dave (or anyone knowledgable) - The Co-operative Extension agents told me not to remove leaves above the green tomatoes to avoid sun scald. Intuitively, I just want to cut off everything that looks sick even if all that is left is t stem and a branch with green tomatoes. What do you recommend?
Elaina

This post was edited by MissRumphius on Thu, Aug 1, 13 at 21:48

The Co-operative Extension agents told me not to remove leaves above the green tomatoes to avoid sun scald

***********
sun scald on what ? fruits? nonsense. lots of tomato fruits are exposed to sun and nothing happens to them.

While defoliating the plant does increase the risk of sun scald to the fruit - a very real issue - it also helps slow the progression of the disease and the spread to other plants since it is primarily windblown.

So it is a trade off to a degree. We often recommend stripping the foliage and providing an alternate form of semi-shade to the plant if possible as well as picking the fruit at first blush (color break) to finish ripening indoors out of the direct sun..

I'd speculate that in your zone the risk of sun scald may be far less than when compared to zones further south but only you can judge the degree of sun exposure your fruit will get and the degree of risk. Try for a balance between providing some cover but getting rid of as much of the infected foliage as possible and then spray well.

Hope this helps.

Dave

Yeah ! I didn't notice that OP is gardening in zone 4, way up north and the county extension agent warns him of sun scald. It is like this person is dying of hunger and somebody is warning him of high cholesterol .
Those guys should go and find a job that they can handle IMO.

Dave - Thanks for all the thoughtful advice. I'm now off to defoliate my poor plants.

Elaina