What is this disease on my rhus aromatica - Ask Extension
Two years ago our landscape designer planted (in fall) 5 rhus aromatica: they had lost all their leaves before they were planted so their health at pl...
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What is this disease on my rhus aromatica #798547
Asked June 29, 2022, 12:23 PM EDT
Two years ago our landscape designer planted (in fall) 5 rhus aromatica: they had lost all their leaves before they were planted so their health at planting was a bit suspect. They leafed out last year but did not thrive. This year they leafed out some although we lost one completely and now 3 of them have what looks like diseased leaves (pictures attached). Maybe anthracnose? There is also some similar leaf curl and wilt on a spice bush, and we lost a young (and never healthy) witch hazel about a month ago to a similar looking disease. How can I identify the problem and then solve it? Apologies for the dappled light in the pics that makes them a bit difficult to see clearly.
Prince George's County Maryland
Expert Response
We suspect this is an establishment issue, where the roots never established well due to soil conditions or poor health at the outset. Is the soil in this area on the wetter side, or stay drier? In our experience, this species prefers soils with good drainage and occasionally dry conditions compared to even moisture.
If this in an infection, a root rot (usually preceded by overly-wet soil) or perhaps stem canker blocked moisture access to the foliage and stems, resulting in their dieback. Anthracnose symptoms manifest differently than what we see in the photos and do not cause wilting; we also aren't familiar with any problematic anthracnose diseases on sumac. Usually, though, new plants in their first few years of growth succumb to lack of establishment rather than pest or disease issues. Botryosphaeria is an opportunistic fungal disease which takes advantage of plant stress, particularly from drought, in case this area runs a bit dry rather than staying too wet.
Was any herbicide used in this area?
The plants having lost their leaves prior to installation in autumn is not necessarily a warning sign, particularly if the planting occurred in October or November. Potted plants often shed foliage a bit sooner than in-ground and established plants because roots are more easily stressed by life in a pot. If the young plants were not occasionally checked for water after planting (even in winter, during prolonged thaws if we didn't get precipitation), that could have hampered root development.
Similar symptoms on Spicebush and Witchhazel aren't necessarily related to each other or the Sumac ailment since wilting and branch dieback can occur due to a variety of factors -- anything that interrupts water flow up the branch, which includes an array of pathogens, wood-boring insects, root dieback, and physical injury. Delayed dieback from last year's periodical cicada egg-laying activity is also still occurring on some shrubs and trees, though the scarring from this is readily visible, unlike some of the above causes.
Pesticide (including fungicide) use is not effective in this situation and the plants likely need to be replaced. You can try to trim back all wilted and dying growth to see if roots resprout, but we suspect the root systems aren't in good enough shape to support regrowth. You can try again if you want to grow Sumac in this spot, assuming it gets at least a half-day of direct summer sun and doesn't stay too wet, and planting this time of year would be fine if you can keep the plants monitored for watering needs. Otherwise, late summer to early autumn (August-September) would be a good time to plant.
Miri
If this in an infection, a root rot (usually preceded by overly-wet soil) or perhaps stem canker blocked moisture access to the foliage and stems, resulting in their dieback. Anthracnose symptoms manifest differently than what we see in the photos and do not cause wilting; we also aren't familiar with any problematic anthracnose diseases on sumac. Usually, though, new plants in their first few years of growth succumb to lack of establishment rather than pest or disease issues. Botryosphaeria is an opportunistic fungal disease which takes advantage of plant stress, particularly from drought, in case this area runs a bit dry rather than staying too wet.
Was any herbicide used in this area?
The plants having lost their leaves prior to installation in autumn is not necessarily a warning sign, particularly if the planting occurred in October or November. Potted plants often shed foliage a bit sooner than in-ground and established plants because roots are more easily stressed by life in a pot. If the young plants were not occasionally checked for water after planting (even in winter, during prolonged thaws if we didn't get precipitation), that could have hampered root development.
Similar symptoms on Spicebush and Witchhazel aren't necessarily related to each other or the Sumac ailment since wilting and branch dieback can occur due to a variety of factors -- anything that interrupts water flow up the branch, which includes an array of pathogens, wood-boring insects, root dieback, and physical injury. Delayed dieback from last year's periodical cicada egg-laying activity is also still occurring on some shrubs and trees, though the scarring from this is readily visible, unlike some of the above causes.
Pesticide (including fungicide) use is not effective in this situation and the plants likely need to be replaced. You can try to trim back all wilted and dying growth to see if roots resprout, but we suspect the root systems aren't in good enough shape to support regrowth. You can try again if you want to grow Sumac in this spot, assuming it gets at least a half-day of direct summer sun and doesn't stay too wet, and planting this time of year would be fine if you can keep the plants monitored for watering needs. Otherwise, late summer to early autumn (August-September) would be a good time to plant.
Miri
