Hello Kit,

More information can help us narrow-down a possible diagnosis. The plants pictured appear to be Aucuba (Aucuba japonica, sometimes called Spotted Laurel or Japanese Laurel, despite not being related to true laurels)...is this correct? Different conditions cause stress to different plants, so knowing what the plant is can help determine where the problem lies. Can you share a photo of the entire plant(s) and where they are growing? We see that there's a wall close to the shrub, which can potentially reduce air circulation that keeps it cooler in summer and which discourages leaf infections in stretches of wet weather.

How much direct summer sun are the plants exposed to? (Full sun is 6 or more hours of unobstructed sun.) Aucuba, as an example, does not thrive in full sun and can turn yellower and decline if stressed by intense light; they are more well-adapted to semi-shade, or a location that faces north or east where the summer sun tends to be blocked by a building after midday or so.

Is there a roof downspout outlet nearby, or a leaky garden hose spigot? Aucuba needs well-drained soil to thrive, and while they do not appreciate drying out too much (last year much of Maryland experienced a drought, for example), they also dislike staying too evenly damp.

Aucuba sometimes develops a leaf infection that causes blackening and stem dieback, though there is no curative treatment for it; you can only prune out the damage and wait for regrowth. No serious insects bother Aucuba that we have seen, so often its stress is due to growing conditions rather than a pest issue or a more serious infection, but we can see if anything stands out to us in the additional photos.

Miri

Hi Miri,

Thank you for your help. Although I did not plant these bushes, I believe they are Japanese Laurel. They are planted as foundation plants on the side of our house. They probably get 6 hours of sun per day. They looked wonderful and healthy last year, so this is new. Should I fertilize them?

Best,

Kit

Hello Kit,

Thank you for the additional information. It sounds like the amount of direct sun is a bit more than they'd prefer, so that might be adding to whatever other stress is bothering them that we can't identify. If possible, it might help to move the shrubs into an area with more afternoon shade. Aucuba can handle a higher pH (soil being less acidic) than many other shrubs, but perhaps the acidity is still outside of its preferred range in this location, which is affecting how well the roots function to absorb nutrients. Rather than adding fertilizer, since it might not be needed, a move to another spot might also help the roots access what they need if the soil is a little more acidic than it might be up against the foundation. This type of soil acidity issue probably would not cause such a drastic change in appearance in less than a year (neither would a fairly sunny exposure if the plants grew fine in it last year, unless a nearby tree was removed or its shadow doesn't shade the plants any more due to decline), but it might be a contributing factor.

There is no direct treatment recommended, and while we can't identify the exact cause of decline at this point, a new planting site might gradually alleviate the plant's symptoms. Individual leaves can't heal and aren't always capable of greening-up again once they get yellowish, but any new growth that emerges after a move should look better if the plant is recovering. Whether you move them or keep them in place, monitor them for watering needs as we move into summer, feeling the soil about six inches deep and watering only once the soil starts to feel somewhat dry to the touch at that depth.

Miri