Cherry laurel browning and dropping leaves

Question: I planted several new cherry laurels this spring.  I was noticing some yellow leaves so I began watering regularly since we haven’t had much rain in the past couple weeks and it’s been extremely hot.  Now, some bushes are dropping brown leaves mainly from the bottom of the bush.  The one in the picture looks particularly unhealthy with a section of leaves on the right side being completely brown.  I would think if it’s water related it would brown all over?  Any  suggestions greatly appreciated before it’s too far gone to save.  Thank you!

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 June 21, 2024, 2:28 PM EDT
response: We agree that if the symptoms were only related to root moisture, that the entire plant would probably be affected. (Overwatering might cause localized symptoms first...more on that later.) Instead, the branches turning paler and brown might be dying from injured wood, an opportunistic infection (some of which take advantage of heat- or drought-stressed plants), or wood-boring insects in the lower, thicker part of those branches. It's hard to tell from symptoms alone, since any of the above can cause this kind of dieback. You can use the information on our page Cherry Laurel: Identify and Manage Problems to see if certain pest or disease indicators are present.  Since the dying branches need to be pruned off (since they will not recover), you can also cut into the wood near the base of the removed branch and see if there is staining of the wood, tunneling or sawdust, or other signs of damage. Vole gnawing would leave chew marks and missing bark around the plant crown (where branches emerge from the roots), so you can inspect the base of the shrub as well, and make sure any mulch there is not piled against the crown; keep it pulled back a few inches to maintain good airflow.  As a guideline, when monitoring shrubs for watering needs, feel the soil around six inches deep next to the root zone, and water well only once it becomes somewhat dry to the touch at that depth. If damp when checked, watering can probably wait. How well-loosened the root ball was when the shrub was planted can impact how easily it starts to establish and become more self-sufficient with regards to moisture access for the roots. (Was it in a container or burlap? If potted, were the roots disentangled a bit before planting? If burlapped, was the burlap and any twine or wire holding it in place removed?)  If over-watered, roots lose access to oxygen in the soil, in essence "drowning." If not killed by that alone, their weakened state puts them at risk of infection by "root rot" pathogens, for which there is no treatment. Sometimes root rot symptoms, which can overlap with underwatering symptoms or other ailments, are delayed in manifesting, especially in evergreens. By checking the soil prior to watering, you can make sure a plant is only being watered when it's needed, to reduce the risk of over-watering. If the soil drains well, cherry laurel are fortunately fairly adaptable plants, though can still be stressed by extremes of soil moisture and high heat, particularly if that nearby white wall is reflecting lots of sun or heat during summer.  Miri

responder: The Question Asker Replied June 22, 2024, 7:02 AM EDT
response: Thank you for your advice.  You provided so much information in great detail.  I’m so glad I found you as a resource.     I cut back the two dead branches.  I don’t see any signs of damage.  I guess I’ll assume overwatering is the reason for now.  I began watering more frequently a few weeks ago when I noticed some yellow leaves.  The watering seemed logical since it’s been hot and dry the past couple weeks.     The bush is one of a grouping of three on the right side of my porch that I planted this spring to replace a couple cherry laurels (slightly different variety) that were dying/weren’t growing well and scrawny.  It’s even more interesting that the grouping of three that I have on the left side of my porch are thriving.     Thank you again for your advice.

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 June 24, 2024, 11:23 AM EDT
response: You're welcome!  Soil drainage and moisture retention can vary within a surprisingly short distance in the same yard, so perhaps the two sites differ just enough in the soil moisture levels that one group is struggling while the other is less stressed. It's hard to say, but feeling the soil before watering will help determine when it's needed so the risk of over-watering is reduced.  Miri