Cucumber plant's leaves are dying.
I am growing 3 varieties (Sweet Success, Marketmore and Little Leaf) of cucumbers in my small garden plot in southern Wisconsin. The Little Leaf is doing pretty well and it is only showing slight yellowing of leaf edges but the other two larger leaved varieties have rampant disease or ailments of some sort. The older growth leaves are quickly developing yellow and brown spots which quickly expand and the leaves die. They are all starting to produce fruit and the fruit does not seem to have any blight or problem. I have looked at your website and can't figure what is going on from the photos you have posted. Is it fungus, is it mildew or both? Am I watering or fertilizing to much or too little?
I have attached a photo montage of the plants affected. I numbered the different images in the montage in case that helps for referencing in your response.
It has been very hot for 2 weeks and I have been watering 3-4 times a week, given them a good soaking. They soil does not seem to be wet or too dry. I have used organic vegetable plant fertilizer and some Milorganite. I added manure and humus soil and tilled in before planting.
Can you tell by the photos what is causing my cucumber leaves to die?
Thank you in advance for your help,
Montage of my ailing cucumber plants