When cherry laurels are happy in their planted positions they show it by thriving, and when they are not you know it too. The cherry laurel in your first photo looks severely stressed and could possibly die. How old are they?

One of the most common insect issues these plants have are from a sap sucking scale insect, and we don't see evidence of that in your photos. This blog post discusses some more common issues: https://marylandgrows.umd.edu/2019/01/07/qa-whats-wrong-with-my-cherry-laurel-shrubs/

These plants also will not do well in areas where the soil drains poorly, which can lead to die back. How is the soil down near the road? Any salt spray? Too dry could also hurt them. Are they ever watered? Depending on how old they are and how they were cared for after planting, some may have failed to establish properly.

As the blog mentions, take a careful look at the lower trunk. Any borer holes? Does the plant pull out of the ground easily and show teeth marks? (Possible vole damage from gnawing).  

Pull back the mulch you just laid. Can you see a widening or flare before the trunk goes into the ground or is it straight up and down like a telephone pole? Plants planted or mulched too deeply (more than 2-4 inches over the roots can smother them.... and it looks like they are planted in or mulched with stone under the mulch you just added? How thick is that layer? Dig down until you see the flare.

You might consider digging up the worst affected one and looking at the roots to see if they are dried and dead, perhaps still in the shape of the pot it was originally in? Are they wet and slimy?

We think that your issue is most likely due to the unhappy ones being in a location that is drier, wetter, hotter or that they are planted differently than those that are doing well.

Christine

Hello Louis,

Yes, for the most severely-affected shrubs (such as the nearly-leafless plant in your first image), they should be replaced. The others in the photos don't seem too badly affected and can be kept for now. Leaf drop in shrubs can result from an array of stress factors, including as part of a normal growth cycle. This is why, as a primary symptom, it is difficult to diagnose.

Despite being evergreen, individual leaves have a limited lifespan, and plants will shed some of their oldest leaves each year; such leaves tend to be in the interior and lower portions of the shrub. What you are currently seeing on the other cherrylaurel in the planting may be due to this. Many evergreens (cherrylaurel, euonymus, holly, etc.) routinely shed their oldest leaves around the same time new ones are emerging in spring and early summer, though others (pines, azaleas) do so in autumn. The degree to which evergreen leaves are shed any given year depends partly on how stressed the plant may be, plus how quickly it's been growing. Nutrition can play a part too, though only a few nutrient deficiencies would result in leaf loss that doesn't first show discoloration on the younger growth.

To complicate matters, excessive nutrients (which include "salts" from ice-melt and fertilizer) can also cause leaf loss. In that case, it is because the high concentrations interfere with the roots' ability to absorb water. The plant essentially suffers drought stress since the roots have been damaged and aren't able to function properly, even in adequately-moist soil. Going forward, fertilizing ailing plants is not recommended unless a specific nutrient deficiency is manifesting or unless they seem perfectly healthy aside from poor vigor, since it cannot correct for other stress factors and may actually worsen a plant's condition.

Holly-tone is a suitable choice for acid-loving plants, but in and of itself probably doesn't contain enough sulfur to actively alter the soil pH by much; if anything, it may be more of a maintenance dosing to keep pH stable, though our soils tend to be acidic in much of MD anyway. Aside from this, cherrylaurel is known to have a good tolerance of a range of pH values, so is not acid-loving to the degree that azaleas, camellias, and hollies are.

We agree that the planting sounds too far from the public street to suspect ice-melting salt from that source, but does either driveway (yours or your neighbors) receive ice-melt treatments? Does the row of plants slope downhill a bit towards the dying shrubs, where runoff might be collecting?

An image of the overall site and driveway might be helpful, in case we spot other environmental factors that could be contributing to this localized damage. We see what looks like a stone mulch beside the planting. Does this extend under the bark mulch? Do you know if there is landscape fabric underneath either layer?

As Christine mentions, removal of the mostly-dead shrub(s) may prove telling, since signs of borers or vole gnawing will be much more apparent when you can inspect the bark and wood interior more closely. You are welcome to send additional photos of symptoms you find that you are unsure of.

The lack of new growth is concerning and suggests issues with root health. Is the planting being checked for water regularly, particularly in prolonged dry spells like the one we are currently experiencing? Dry periods in autumn, which we've also had in recent years, can not only damage roots but result in fewer viable buds that would normally be contributing to the following year's leaf growth.

Miri