It probably is. You are watering too often, I think. You shouldn't water at night. Water in the early morning so the leaves can dry off if you get them wet. Try not to get any water on the leaves. I would suggest you stick the soil with your fingers or something to measure if the soil needs water or not. Cut off any bad leaves and throw them in the trash, not the compost pile.

Housekeeping, housekeeping, housekeeping! PM spores overwinter in fallen leaves, vines, etc. Don't forget the importance of that step....it's crucial. PM does NOT need free water in order to germinate; dew does NOT increase its activity. As a matter of fact, the spores can be sprayed off with plain water if caught before the cells are infected. I use two things to prevent PM on problematic veggie plants (aside from housekeeping) . The first is Neem oil, but that can't be used when the temperatures get too hot. The second is 'Surround ', a wettable kaolin clay powder. PM spores cannot penetrate through a fim of Surround '. It also has the added benefits of hugely reducing insect pest damage, as well as heat and sun stress. I love the darned stuff.....and it is absolutely organic. Surround is a protectant, a physical barrier to windborne disease propagules.

Roses are more vulnerable to PM when their foliage isn't getting enough water from their roots, which often happens on young or transplanted roses. Keep the plant well watered though not drowning and as it settles in it may be more resistant, if it is not a cultivar prone to PM. Some are. You can spray off the foliage with water every morning, provided it is sunny/warm enough to dry in a few hours, to wash off spores. You could spray with a fungicide if you are really concerned. PM spores float through the air for miles and miles, there isn't anything you can do about that except keep your plants as strong and healthy as possible, so their natural resistance can best protect them.

Yes be concerned and alarmed but not paranoid for I will give you my advise on a solution that will take a tiny bit of effort and repetition mix a powdered milk solution with water and spray upper and lower leaves and soil and sprinkle powdered milk all over the surface of the soil after you water them with a 9 to one ration with water and milk then next couple of days spray with baking soda and water mix the next couple days spray with 1 tablespoon vinegar mix with 1 gallon water, take a blender and put in almost hot water and puree many garlic cloves then strain thru regular strainer to catch most of the pulp into a finer yogurt type strainer now you have your concentrate that you can store in frig up to 3 to 4 weeks use alone diluted and spray plants or mix in combination with all the above if you wish alternate with the baking soda then next 2 or 3 days apple cider vinegar once in awhile top and bottom of leaves and the soil surface stay up on all these suggestions for awhile even on near by plants cause this has spread and will come back do this for about two weeks then lay back and do every 2 weeks and you should have total success with you hard earned harvest(P.S. very lightly sprinkle soil then leave with cinnamon important lightly on leaves heavier on soil,plus cinnamon keeps ants away