8 y/o Laurel branches wilting and dying - Ask Extension
I noticed my 8 y/o Laurel bush had a branch that wilted and died. We pruned the branch and now notice that another branch is starting to wilt. I also ...
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8 y/o Laurel branches wilting and dying #811214
Asked September 17, 2022, 6:11 PM EDT
I noticed my 8 y/o Laurel bush had a branch that wilted and died. We pruned the branch and now notice that another branch is starting to wilt. I also noticed a couple of yellow leaves on the branch. The rest of the plant seems healthy but I am concerned that whatever is happening will continue to the other branches once the current one is dead. I also have another healthy Laurel next to this one and I really don't want to loose either of them. We had a very hot summer and I initially thought it was suffering from lack of water. After watering the plant (in addition to the rain we have received the past few weeks) and pruning the dead branch I notice this is happening again. Is there anything I can do? Will this continue to spread and kill the entire plan? Will it spread to the adjacent Laurel? Thank you!
Howard County Maryland
Expert Response
Patchy branch leaf discoloration, curling, and wilting suggest something is interrupting the water supply for those individual branches. That could be due to physical damage near the base of those stems, tunneling in the wood by boring insects, or an infection clogging-up or even killing those water-conducting tissues. In all cases, the affected growth needs to be pruned out, and even if caused by a pest or disease, treatment is not possible at this point.
To determine which it might be, inspect the bark on or near the base of the symptomatic stems. If gnawed, voles might be responsible, and they tend to feel safer chewing on plant crowns (the main growth points at the soil line) if sheltered from predators by dense plant growth or thick mulch. If there is cracking or sawdust visible around the stem base instead, or an emergence hole a bit smaller than a wood pencil diameter, then peachtree borer (the caterpillar of a moth that looks vaguely wasp-like as an adult) may be responsible because it targets stressed cherrylaurel and other peach/cherry relatives. You can cut apart dying branches lengthwise to see if a borer or its tunneling is visible inside the stem. If fungal, a pathogen like Botryosphaeria is a possibility, which takes advantage of drought stress or stem injuries, or other pathogens that kill roots or stems during periods of excessive moisture. (The Botryosphaeria page focuses on Rhododendron, but it can impact a wider array of other shrubs as well.)
To reduce the risk of recurrence, keep the plants minimally-stressed where possible by monitoring them for watering needs periodically during periods of dry or hot weather. Feel the soil about six inches deep next to the roots and water well only when it's becoming relatively dry to the touch at that depth. Cherrylaurel are fairly adaptable plants and not easily stressed, but overly-dry and overly-wet root zones can cause them damage directly or can lead to some of the problems outlined above. Since no curative treatments are available, prevention is the best approach. Make sure mulch isn't covering the crown (keep it a few inches clear of the trunk base). We can't say why after eight years of presumed good growth these plants suddenly contracted this problem, but perhaps the right combination of stress factors (whether chronic or acute, or both) resulted in greater vulnerability at this point in time.
Miri
To determine which it might be, inspect the bark on or near the base of the symptomatic stems. If gnawed, voles might be responsible, and they tend to feel safer chewing on plant crowns (the main growth points at the soil line) if sheltered from predators by dense plant growth or thick mulch. If there is cracking or sawdust visible around the stem base instead, or an emergence hole a bit smaller than a wood pencil diameter, then peachtree borer (the caterpillar of a moth that looks vaguely wasp-like as an adult) may be responsible because it targets stressed cherrylaurel and other peach/cherry relatives. You can cut apart dying branches lengthwise to see if a borer or its tunneling is visible inside the stem. If fungal, a pathogen like Botryosphaeria is a possibility, which takes advantage of drought stress or stem injuries, or other pathogens that kill roots or stems during periods of excessive moisture. (The Botryosphaeria page focuses on Rhododendron, but it can impact a wider array of other shrubs as well.)
To reduce the risk of recurrence, keep the plants minimally-stressed where possible by monitoring them for watering needs periodically during periods of dry or hot weather. Feel the soil about six inches deep next to the roots and water well only when it's becoming relatively dry to the touch at that depth. Cherrylaurel are fairly adaptable plants and not easily stressed, but overly-dry and overly-wet root zones can cause them damage directly or can lead to some of the problems outlined above. Since no curative treatments are available, prevention is the best approach. Make sure mulch isn't covering the crown (keep it a few inches clear of the trunk base). We can't say why after eight years of presumed good growth these plants suddenly contracted this problem, but perhaps the right combination of stress factors (whether chronic or acute, or both) resulted in greater vulnerability at this point in time.
Miri
