Although there are pathogens and some insect pests that take advantage of plant stress to start infections or infestations (the fungal canker Botryosphaeria being a primary culprit as a result of drought), the drastic and seemingly rapid nature of the pictured plant's demise suggests something else, like direct root damage from the drought itself. Was the plant being monitored for watering needs this summer? While parts of central Maryland are not officially in drought status currently, for much of the growing season, there was a drought that was impacting plant health.

Evergreens don't readily manifest symptoms of stress until the damage has already become fairly advanced, so unless the soil is checked, it can be hard to tell when they are getting too dry. Similar symptoms can occur if plants are over-watered, but unless lots of water was being applied quite frequently to this plant, we think that's much less likely than under-watering/drought.

Brown foliage will not recover, and since the dieback looks too extensive, unfortunately the plant will need to be replaced. Now (September) is a good time to replant if you are interested in doing so, though we would recommend not waiting too far into October to plant since roots need time to get established (especially for evergreens) to avoid "winterburn" damage to the foliage. If you needed to wait for replanting, spring would be fine.

Miri

Hi Miri, 

Spider mites can damage evergreens, but their feeding injury looks different than this, and there would be other prominent indications of a high population if they were responsible for this damage (which is too drastic and extensive for mites). Spiders are not the same as spider mites, and they are beneficial because they consume other insects/arthropods, including garden pests and biting flies, and do not damage plants. Lab examination of the dead material is not necessary and probably wouldn't be too diagnostic if the plant is as dried-out as it appears to be; semi-live tissues that are earlier in the stages of dying from infection (when a pathogen is present, at least) are used for diagnosis if the symptoms aren't distinctive enough. Once a disease has progressed too far and caused too much dieback, it can be harder to isolate the original culprit.

Drought can weaken or kill one plant and leave others apparently unscathed. This can be due to a range of factors, such as drainage from one spot to another (which can vary under the surface, even if the ground looks level and uniform), how well roots established and how healthy and extensive they were before the drought began, if there is any competition for moisture with other nearby plants (including any shade trees that might be closer to one plant over another, even if not casting shade on them directly), and genetic variation from one individual to another, where one might be more prone to environmental stress. If the evergreens you mention are different cultivars or even different species, then they don't all necessarily respond to drought in the same way, or have the same degree of vulnerability.

It's fine to plant just about anything now (September into perhaps mid-October), including Skip Laurel, but monitor any new planting carefully for watering needs (drought or not). We've seen several mid-size or mature Skip Laurel (plus Arborvitae, Leyland Cypress, Hollies, and more) succumbing to drought stress this year, and that will likely continue into next year since the impacts of drought aren't always as immediate as we would expect, especially for evergreens.

Miri