We have several mature holly bushes that have large areas (up to 1/3 of the shrub) on which the leaves have turned completely brown. The ends of the branches have new green growth appearing on them. The unaffected portions of the shrubs seem healthy and show no signs of spotting of leaves or insects. The shrubs are planted in 2 separate beds, each about 20 feet long. Any diagnosis or remedy?
Hummmm, that sounds strange. Is the entire shrub affected, or is most of the damage on one side? If the damage is on one side, my first thought would be that damage from herbicide drift has occurred. The main reason I think this is from your statement that the new growth looks good. Glyphosphate herbicides, ( like Roundup ) only kill foliage, not roots and woody stems. Also, why would shrubs in two different areas exhibit the same problems? Obviously, it isn't location. If the shrubs were mine, I'd wait to see what happens. If the new growth continues to do well, you can trim mid-March to eliminate bare stems. If the new growth starts spotting and turning brown, I'd take samples to your local agricultural extension office for identification and recommendations.