Extensive powdery mildew on cherry laurels - remove shrubs of treat?

Question: The cherry laurels our newly acquired house appear to have an extensive infestation of powdery mildew that is covering about 75% of the trunks. Please see the photo. I sprayed them once with "Garden Safe Fungicide 3" a few days ago and it appears unfazed.

We need to decide whether to remove the shrubs or to treat them.  My understanding from internet research is that once a plant has been heavily infested by powdery mildew, even if successfully treated, it will require preventive spraying on a regular basis in future years. While these are lovely plants, I do not want to continually expose myself to chemicals and would rather remove them if I would need to spray them more than a few times.

Please advise with your opinion about what treatment (including recommended chemicals) would be necessary both to kill off the infestation and to prevent future infestation. Please also advise if you would recommend removal instead.

Thank you so much!

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied August 21, 2024, 2:17 PM EDT
response: This is not powdery mildew, which grows on foliage but not on bark, so you can discontinue the fungicide. This is White Prunicola Scale, an insect pest that can be fairly common on stressed Cherrylaurel shrubs and their relatives (mainly flowering and fruiting cherry trees). Since the scale population is this high, the infestation been present for some time...probably building up to this point for several years. Management is possible with multiple treatments using insecticide (if you opt to do so, using organic products or otherwise), but if the plants are in too great a decline (having many dead branches), they are better off replaced than rehabbed. Information about scale insect management options can be found in the linked pages above.  The plant pictured appears to be planted much too close to the nearby wall, which is limiting air circulation and root room for the shrub. If you put in replacements, mature shrub size will depend on the variety grown, but usually is at least 4 to 5 feet wide in branch spread at maturity, so the center of the plant (the trunks, basically) should be located at least 3 to 4 feet away from a wall.  While very plant species has at least some pests and/or diseases they are vulnerable to, generally infections and infestations are more severe or more likely to occur on plants that are first stressed by growing conditions (high heat, over- or under-watering, etc.) or which are over-pruned or used in locations where they don't fit. When planting a hedge or screen that would typically involve using multiple individual plants in a group or row, we recommend selecting a mix of species rather than just one. While this might look less uniform, it supports the resilience of the planting as a whole, since different plant species have different vulnerabilities and tolerances to stress. A mixed-species planting can still look more formal (versus naturalistic and potentially chaotic), if that is aesthetically important to you, by using repeating patterns of the different species being grown so their placement looks intentional and symmetrical. Cherrylaurel are adaptable plants and one of the few evergreens tolerant of a range of conditions and regular trimming, but they can be over-planted because of those very traits.  Miri

responder: The Question Asker Replied August 21, 2024, 2:37 PM EDT
response: THANK YOU, MIRI!!!Thank you so much for your rapid, informative, and helpful response. This definitely helps me going forward. Elizabeth On Wed, Aug 21, 2024 at 2:17 PM Ask Extension <<personal data hidden>> wrote:

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied August 21, 2024, 3:15 PM EDT
response: You're welcome!