Winterberry holly disease - Ask Extension
Hello. I’ve had this Jim Dandy winterberry holly for 4 years, and this year it didn’t flower and it’s leaves have strange markings. It has few l...
Knowledgebase
Winterberry holly disease #842151
Asked July 23, 2023, 1:58 PM EDT
Hello. I’ve had this Jim Dandy winterberry holly for 4 years, and this year it didn’t flower and it’s leaves have strange markings. It has few leaves overall but its suckers appear healthy. I did water it during the extended dry period.
Any thoughts on what’s going on with it?
Howard County Maryland
Expert Response
The leaf "burn" appears to be abiotic, meaning it's not due to a pest or disease but rather environmental conditions. Winterberry holly can be easily stressed by drought and under-watering; we've seen them shed foliage, flowers, and/or unripe berries when plants are getting a bit too dry between waterings, even if they are not actually wilting yet. Although they don't need to stay soggy per se, they do appreciate consistent soil moisture. You do mention having watered, but since we don't know how much or how often, we can provide this guideline for the future: feeling the soil about five or so inches down next to the roots to gauge moisture level is a good way to determine when watering may be needed. If somewhat dry to the touch at that depth, a thorough watering is probably due. If damp when checked, watering can probably wait.
Winterberry blooms on old wood (wood produced the prior year), though some references seem to disagree and say they bloom on new wood (current year growth). If indeed it is old wood as most sources state, that means flower buds for this year were developed last summer/fall and remained dormant on the twigs all winter, where they would have been vulnerable to drought stress and other factors. If we had below-average precipitation last year, plants preferring moist soils may have aborted (shed) some buds, or they blasted (died) due to fluctuating temperatures when mild spells were closely followed by rapid chilling. If the plant was pruned at all between flower development and bloom the next year, that too would explain poor flowering/fruiting.
Since this is not a pest or pathogen, no particular treatment is needed, but continuing to monitor for watering needs would benefit the plant. Desiccated leaves may shed but as long as too much leaf drop or branch death does not occur, the plant should be okay. (It would be normal and not concerning for the plant to not necessarily replace those lost leaves this season, though, even as it recovers, given how relatively late in the growing season we are by now.)
If any of the branches carrying burnt leaves have old periodical cicada egg-laying damage on the bark, that might explain why some growth was more vulnerable to drought stress compared to other growth (say, the suckers), since the old injuries may have impacted water flow through those twig tissues even if the twig itself didn't completely die back. Nothing necessarily needs to be done about this, but pruning those branches back to just below the old cicada damage might help if the problem continues. (If trying this, wait until late winter to prune.)
Miri
Winterberry blooms on old wood (wood produced the prior year), though some references seem to disagree and say they bloom on new wood (current year growth). If indeed it is old wood as most sources state, that means flower buds for this year were developed last summer/fall and remained dormant on the twigs all winter, where they would have been vulnerable to drought stress and other factors. If we had below-average precipitation last year, plants preferring moist soils may have aborted (shed) some buds, or they blasted (died) due to fluctuating temperatures when mild spells were closely followed by rapid chilling. If the plant was pruned at all between flower development and bloom the next year, that too would explain poor flowering/fruiting.
Since this is not a pest or pathogen, no particular treatment is needed, but continuing to monitor for watering needs would benefit the plant. Desiccated leaves may shed but as long as too much leaf drop or branch death does not occur, the plant should be okay. (It would be normal and not concerning for the plant to not necessarily replace those lost leaves this season, though, even as it recovers, given how relatively late in the growing season we are by now.)
If any of the branches carrying burnt leaves have old periodical cicada egg-laying damage on the bark, that might explain why some growth was more vulnerable to drought stress compared to other growth (say, the suckers), since the old injuries may have impacted water flow through those twig tissues even if the twig itself didn't completely die back. Nothing necessarily needs to be done about this, but pruning those branches back to just below the old cicada damage might help if the problem continues. (If trying this, wait until late winter to prune.)
Miri
Hi Miri,
Your point about drought stress combined with cicada damage makes so much sense. All my shrubs were severely damaged by cicadas and still have not yet recovered. Thank you so much for your answer, and I will provide extra water to these plants during future dry spells.
Thank you!
You're welcome!
