Sheri....you can prune 'dead stuff ' at any time. The amount of shade is surely a contributing factor to the shrubs ' decline. But if it MY choice, I would absolutely not limb up my trees in order to give these very common plants more sunlight! The trees contribute real value to your property.....the ligustrum......not so much. In the late winter or early spring, you can cut the plants all the way to the ground....no more than 6 inch stumps. This is the "rejuvenation pruning " we were talking about earlier. In a few short weeks, the plants will begin to rebound rapidly. You'll be shocked at how quickly ligustrum will regrow. It's only a stop gap measure, however. You'll need to begin a fungicidal routine that might not be effective for very long. OR you could remove the ligustrum and replace them with something that thrives in the shade. If you are certain that you have no insects (scale?), then your shade trees should be inspected for scale, aphids, or other sucking insects. Black sooty mold only grows on the sweet liquid excrement of insects. Overstory trees are often the home of the insects and the honey dew rains down on anything below.

We had that happen at one of our rentals, Was told this can happen sometimes as they don't last forever.. We also had this happen at our own house when we installed a gate, it disturbed the roots i think. Anyway, the whole hedge lost all it's leaves and looked dead. After 6 months, i was going to pull it out, but as i checked some of the branches by scrapping the bark off, some were still green but most were dead. I applied chicken manure pellets, blood and bone and seaweed solution every 3 weeks. Well now it's fully green and even flowered. So i suggest scrapping a little of those dead looking branches and checking if they are alive, if they are, give it some fertilizer and cross your fingers. Not sure what type of hedge it is, but ours is a Conifer.

Hello wisconsitom – Thank you for your response. Here are some additional details… I’m located in Zone 7, Long Island NY. This privet hedge is approximately 2.5 years old and had been healthy (at least in appearance) in the beginning of the Spring. They were purchased from a very good nursery and I believe they were in burlap as opposed to pots but I’m not certain anymore as I had both. I trim them on a regular basis and I believe that I have trimmed the hedge twice this year. This property had been neglected for many years and this entire area had been dead trees, brush, and invasive vines like English Ivy and other species whose names escape me. I cleared the property approximately three years ago and planted a perimeter of various shrubs …I have several sections of Privet around the property. This particular section looked very healthy and full, I have been keeping it low and trimming in a pear shaped formation to make certain the bottom gets sun and stays green. The soil is very fertile, it has excellent drainage and gets a good amount of sun each day. Our spring has been pretty good, I usually supplement water if there is any dry spells. There is no grass within 10 feet of this hedge … I have put down both a pre-emergent and broadleaf control, but not in close proximity. I use arborists wood chips as mulch, but I have not recently mulched this area – this is where I get concerned about the Honey Fungus. The thinning of the leaves was very sudden and I’m concerned whatever is causing it might spread … Any thoughts or suggestions would be greatly appreciated. Thank you

If "powder puff" refers to Calliandra haematocephala or C. surinamensis, this is really a shrub rather than a tree and far too low growing to be any attraction to woodpeckers :-) I agree with Mike that it was a older, dead cane that has become infested with insects that feed and process dead wood. Not really any big deal but suggest removing that cane at the base of the plant. That should encourage some newer basal growth as well as remove any future insect issues from migrating into the healthy stuff.