I grow the sunflowers as a wind break for my corn, it also attracts any corn borers to the flower head rather than my corn, and in the end I feed the seeds to the birds after keeping seed for next years planting.
In this part of the UK (Kent) blight on tomatoes and spuds is beginnng to appear. No rain, but someimes early morning mist/heavy dew.
Are you afflitted? Do you spray? Protectively? Curatively?
Thr health of your crops makes my plants look lke refugees from a plague. (Just sprayed my toms; usually doesn't help. People are getting blight INSIDE their greenhoses.)
Hope you continue to escape from pests and diseases. Where are you located? Are your plants irrigated, or do you rely on rain?
You might find Deppe (2nd ed.) an interesting read. She says that Septora resistance is conferred by a single gene. And she implies that with the right sep resistant tom and a few back crosses and a few years you could have your favorite variety complete with sep resistance. (But she also says - in a different section of the book - that if you change one gene for characteristic x, that change can have knock-on effects on other characteristics.)