I'm really late with this reply, but maybe it will help you next year. I keep Christmas tree lights in my fruit trees. The kind with the large bulb; the fairy lights won't help. I have the lights on a thermostat, to go on automatically when temps get down to 40 degrees. It's not a huge help, but I figure it gives me a couple of degrees more leeway, and that's often just enough. Blossoms won't normally get damaged until about 29 degrees, so if I can protect them to 26, it covers almost any spring freeze we have. If you only have 1 of each type of fruit, your problem might be lack of pollination rather than frost. 100% probability that the plum problem is lack of a pollinator. I'm supposed to be zone 5, but that's a joke. Weather is much tougher than zone 5. I'm getting fruit, so I can't see why it would be too cold in zone 7. It's May 5th and there is snow and hail going on outside my window right now. I plant cold hardy varieties and get the latest bloomers I can find. Late blooming will make a huge difference in whether or not you get fruit where there are spring freezes. I suspect I lost the crop on my earlier blooming apricot. We had several night with temps in the teens right after it bloomed. But the apricot that blooms 2 weeks later has lots of tiny baby apricots on it right now.

@milehigh- thanks for the story. It's worth a try. I'll have to look up more info then on planting bare root trees together. However, your Japanese American hybrid tree sounds interesting- the best of both worlds... I didn't know Costco sold fruit trees. I may also look into multi-grated trees. @olreader- we did plant fruit trees 2 years ago (I believe). With last year's late frost, not one bloomed. Supposedly, that's ok as we weren't going to let the trees fruit and instead let them funnel that energy to their roots for strength. So, I can't really say how they are doing- except that: Green Gage- died almost instantly North Star cherry- significant growth Honeycrisp- little growth Potomac and Seckle pear trees- little growth New Haven and Elberta peach- significant growth The peach trees are from Dave Wilson, Pears and plum from Cummins and others were local. I'm not sure if the nurseries make a difference but I'm very excited about peaches this year- IF we don't get a late frost. I'm also going to plant in the ground a Chicago Hardy Fig tree this spring! I have an idea of how we might overwinter it- create a leaf insulating barrier with rebar and chicken wire, unless I can find a better way. I don't really care to dig a trench and bury the thing in our clay soil. Oh, this reminds me, I'll probably post a question about netting the trees to keep the squirrels out. And also about kaolin clay on the apple tree to prevent coddling moths from laying their eggs- though I've read that it's too pricey for a non-farmer.

Daconil does leave a milky white residue and it will pretty much remain on the foliage until washed off at which point its no longer protecting the plant. Thats one thing to be aware of... daconil is a preventative that works by preventing fungus spores from attaching to the leaf surface. I'm not aware of it being able to "cure" fungal infestations that are already present. (Though it is certainly capable of preventing its spread to new surfaces.) Since you are interested in avoiding daconil's visible residue I might look into another fungicide for your trees and ornamentals. Immunox is one I've used that I don't recall leaving a residue. It doesn't list vegetable crops on the label so I would probably keep using the daconil for them... my own experience is that daconil is great at stopping the spread of early blight and septoria on tomatoes when used on a weekly spray regime (longer if you're in a dry period). Looking at your images though I'm not certain you need to spray the plum tree unless you are seeing new damage. Most of what I see in the picture I would attribute to weather related damage (possibly heavy rain tearing the leaves) and some sort of chewing insect, possibly a grasshopper or caterpillar.

This post is rather late compared to the last, but just to put out my 2 cents ... In the Bakersfield area, the big January Freeze knocked down Bougainvilleas, Cut Leaf Philodendrons, Pygmy Date Palms, Banana Plants, Lantanas, Australian Tree Ferns, Jasmines and Bird of Paradise plants. However, quite amazingly, even the most horribly damaged and dead looking plants are pushing up new leaves and shoots. Stark examples include Cut Leaf Philodendrons that looked like rotting stumps that shoot out new growth from deep in the soil and to the side of the old rotting stump. Banana Plants that looked dead and one might be tempted to root up and trash are regaining good height with new growth. About the only plants that I have that are still painfully slow in recovery are two Pygmy Data Palms, one of which is just beginning to put up new growth and the other, still green and tender at the base, just doesn't seem to want to wake up.