My row of foundation yew taxus have a black powder on inner branches. There...
My row of foundation yew taxus have a black powder on inner branches. There are a few brown leaves on tips of branches, which I pruned. I also fertilized bushes with holly tone. What should I use for the black powder? The yews look reasonably healthy except for two bushes, which are about 1/3 to 1/2 height apparently due to deer nibbling over the harsh winter. The nearby azalea tips have also been nibbled by deer. Are those deer pellets one buries in dirt effective against deer (the ones that enter roots to make plants undesirable to deer). What about sprays or other treatments to dissuade deer? Thank you!
It is possible you may be dealing with cottony taxus scale/cottony camellia scale. Sap excretions called honeydew and sooty mold are the major problem caused by this scale but dieback is not common. See our website for more information. If this is not what you are noticing then send us additional photos of the pest and damage. http://extension.umd.edu/hgic/cottony-camellia-scale-shrubs
If you are noticing ladybird beetles, they are helping control the pests and you may want to use the least toxic control method on the scale. Crawlers begin to appear in mid-June and summer on the leaves. You can spray with horticultural oil or soap in the growing season to conserve beneficials.
Unfortunately there are no easy answers when it comes to wildlife problems. During the cold winter deer have been feeding on plants that were supposed to be deer resistant. Yews are susceptible to feeding by deer. If there are no other food sources, it is possible the deer may feed on the plants this spring. When you have deer in the area, it is recommended to plant deer resistant plants and protect the plants that deer like to feed on with fencing or repellents. If you cannot protect your plants with fencing then you may have to rely on repellents. They will have to be reapplied as they wear away in the elements. Follow all label directions.
See our publication on Deer Resistant Ornamentals http://extension.umd.edu/sites/default/files/_images/programs/hgic/Publications/non_HGIC_FS/FS655.pd...
Repellents - https://www.extension.umd.edu/sites/default/files/_docs/articles/FS810-A_UsingCommDeerReps.pdf