The most common cause of yew damage in my part of the country is too much water, especially in clay soil. Having said that, here in KS we had a swampy growing season last year followed by a dry winter. A number of yews browned out during the winter due to root loss from the wet season followed by drying out during the winter drought (called desiccation) - the root loss kept them from drawing enough water. Black vine weevil can attack yews, and also other pests but it sounds more like a moisture thing.

How tall is this hedge? Japanese Spireas usually aren't all that tall. It seems to me you should be able to find something else to replace it if they all go. It may be that they are succumbing to a root-borne fungus. I don't really know. Spireas are in the rose family, and many plants in that family are notoriously susceptible to all manner of pests. I don't recall Japanese Spirea as being that way, but it still could be. There are probably Hypericums that would work as substitutes, provided you don't mind switching from rosy-pink flowers to golden yellow ones.

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.

hey welcome to GW .... first.. see link next.. is your product labeled for monthly use?? and that aside.. the mature ones are impervious to any treatment with their waxy coating.. and you must ID when the babes crawl out and are susceptible to the oil ... and that is once a year .. not monthly ... you are wasting product/money.. if nothing else ... third.. ants are usually around.. to 'milk' honeydew from whatever it is ... they are irrelevant to it all ... and the black is usually a mold as a result of the honeydew ... in other words.. get rid of the scale.. the ants will move on.. and sooner or later the mildew will go away ... the real problem.. is that the mature ones.. look no different if they are dead or alive.. just because you kill them.. doesnt mean they are going to disappear ... and frankly.. when it comes to this point.. i usually have a hard time 'looking' at them for years to come ... and it is then i think about cutting them down ... now i know nothing about this plant.. as i didnt even know it existed before your post ... but if it is like many hedges or flowering shrubs.. there is probably no reason you couldnt cut them to near ground level.. remove EVERYTHING.. treat the stumps for remnants of scale ... and within a few months.. just about have your hedge back .. since there is no insult to the root mass ... and in the meanwhile.. have removed 99.99% of the problem ... [i would burn it.. and find some satisfaction in sending them to the Elysian fields ...funeral pyre and all that ..]... hopefully you can find out if rejuvenation pruning' is an option with this plant .. good luck ken Here is a link that might be useful: link