Seed - best sown as soon as it is ripe in a shady position in a warm greenhouse. Stored seed should be sown in February/March in a warm greenhouse. Germination is variable. When they are large enough to handle, prick the seedlings out into individual pots and grow them on in the greenhouse for at least their first winter. Plant them out into their permanent positions in late spring or early summer, after the last expected frosts. Cuttings of half-ripe wood, 5cm with a heel, September/October in a frame. Fair percentage

Since you don't plan on doing anything to stop the progress of disease in your plants, then I think that you should rip 'em out and replace with something that will thrive in that specific location. I really don't think that humid conditions are a problem for this plant, per se. But if you live in area that sees a lot of cloud cover OR if they are not located in the full sun, leaf spot diseases are likely. Overhead irrigation can be a factor, too. I think of Rapheolepis as being practically problem free....as long as it's planted in the right place, lol. Then all bets are off.

I grow alot of them in my home landscape, and in my church yard as well. In addition to all that has been said, I would make this note. They do not do well in shade. They will grow lanky and not fill out well. They need at least half a day of direct sunlight. Otherwise, they are pretty near the perfect evergreen shrub IMO. One shearing once a year will hold them at the same size indefinitely. OTOH there are no perfect plants, and Indian Hawthornes are not perfect either. When you do that annual shearing you usually have to scalp them to keep them at a certain size. They recover in about a month, though. To keep this problem at a minimum be sure to give them proper spacing so you don't have to be constantly reducing their size. I usually space them five feet apart. They will fill in that space within three years if planted in good soil. Also, the pink flowering varieties seem to be far more susceptible to that spotting thing than the white ones.

Your blueberry can take a bit of afternoon shade with no problem. Production is better when given some good sunlight, but they don't need the blistering afternoon heat. Rapheolepis is a full sun plant, no question. That's where it thrives! Full sun, hot and humid climates, little extra watering. If this plant is grown in a shadier location, you are bound to see some of the very common leaf spot diseases, as well as lanky growth and poor flowering. Take it from me. I lived in SC zone 8b, where Rapheopepis was a very commonly used plant in parking lots, medians, malls, and full sun foundation plantings. Except where the deer were known to browse, lol. Your zone 7 location might be a little borderline (cold) for them.