|I have an upright yew that is turning brown in spots. Thought it was spider mites last summer and treated but continuing to die in places. Can you help?|
|It would appear that insect or disease problems might be the cause, but yews are typically not bothered by such things so more inspection and diagnosis is certainly in order. The yew gall midge can cause damage to the foliage and weevils can damage the roots, which can show up as dead branches. Yews don't like "wet feet" and can develop root problems if their roots are kept too wet. Although considered relatively drought-tolerant, too little water can also cause problems as well.
Winter damage also can affect yews. Winter injury occurs as a result of rapidly changing temperatures during the winter, bright sunshine, and inadequate water reserves in the root system of the plant. Plants usually show the first symptoms of winter injury in late winter through spring, and browning is most pronounced on the south and west sides of the plants. Although foliage turns brown, if buds remain green and viable, the plant may recover as the spring progresses.
You may want to prune some of the affected foliage off the plant and take it to your local cooperative extension office for positive diagnosis. Staff can use a microscope to confirm or eliminate insects and disease pathogens. Or, you can simply prune out the affected plant parts. New growth should cover the pruning cuts over the summer season. Good luck with your yew!