The Dying Yew Shrubs
My Yew shrubbery is diseased and I lost 4 shrubs from the winter of 2017-18. I removed the dead shrubs this past winter hopping that would have stopped the disease from spreading to healthy shrubs. Unfortunately, the disease is moving to healthy shrubs. What can I do to stop the spread of the diseased shrubs?
District of Columbia County District of Columbia
Yews hate 'wet feet.' Meaning, they do not tolerate growing in saturated soils. Since Maryland had abnormal (twice normal) rainfall last year, yews are dying all over the state. The wet soils lead to root rots that kill the yews.
Improve the drainage around your yews, if possibly. Dry out the soil if you can. Remove mulch if over-mulched. Mulch should never be more than 2-3" deep and should never touch the base of shrub or tree, but be back a few inches.
Most plants do not tolerate saturated soils for long periods. They like moist soil, that drains well so water moves through and does not sit. When soil fills with water, the water drives out the oxygen in the soil pore spaces. And, believe it or not, roots must have oxygen.