Knowing What Plants Do

May 9, 2016 | Gardens

I got a call yesterday from someone who was puzzled about some shrubs that weren’t doing well. She called them “cherry laurels” (Prunus laurocerasus) and said that they looked dead. She’d consulted area landscapers and master gardeners, and had gotten so many opinions about these plants that she didn’t know what to do. One person said they had a fungus and they needed to be ripped out, while another suggested that scale was the culprit.

After asking her if the entire branches looked brown and dead (“No, just the leaves.”) and if there was any sign of the dark grey powdery sooty mold on the lower leaves or stems that would indicate a scale infestation (“No, they are either brown or green. No sooty mold.”) I told her what I thought. “I’d bet money that these plants just have winter damage,” I said.

Why would I make that call based on a phone conversation, without seeing the plants? Because that’s what cherry laurels in this area do on Cape Cod. I’ve had a number of these plants, from the upright “skip laurels (Prunus laurocerasus ‘Schipkaensis’) to the low-growing ‘Otto Luyken’ and they are prone to two problems: shot-hole fungus and winter burn. In the early spring these plants can look like hell.

Had she come to me with this description of her cherry laurels in July or August I would have been perplexed and wanted to see the plants, the pattern of the browned leaves (all over the plant or just one side?) and the area where they were growing. Because browned leaves in the summer would be unusual for this Prunus. But at this time of year, we can be 99% sure that it’s winter burn because that’s just what these plants do.

I advised her to wait and watch. If I’m right, her plants will drop these burned leaves in May and by early June they’ll be covered with fresh green shoots. At that point she can trim off any stem tips that have remained black with die-back.

Here is how my 'Otto Luyken' cherry laurels look right now. I don't bother cutting off the browned leaves because usually the plants drop them when the new growth comes in.

Here is how my ‘Otto Luyken’ cherry laurels look right now. I don’t bother cutting off the browned leaves because usually the plants drop them when the new growth comes in.\

 

I still like this plant – especially the short variety, ‘Otto Luyken’ because it grows well in shade and is a useful plant for foundation plantings that can’t grow too high. In areas that are protected from winter wind and winter sunshine they get less burn.

Note: The shothole fungus can be pretty well controlled by making sure that the plants aren’t hit with a sprinkler too frequently. It can be worse in a season that’s extremely wet and cool, but I find that most often this problem shows up when an automatic sprinkler is set to go off too often.

 

 

 

15 Comments

  1. Janet Logan

    This is VERY helpful, CL. My Otto Luyken looks exactly like that, and I was getting worried. Good to know it’s only winter damage, and the brown leaves will start falling off soon. Thank you! 🙂

    Reply
    • CL Fornari

      Glad it was helpful, Janet!

      Reply
  2. Christin Conly

    I have two 9 month old 45 gallon cherry laurels side by side and one looks like these pictures while the other has a few yellow leaves. The brown one with “winter damage” is not growing anymore and the other one is outpacing it. I’m in Zone 8, central Texas and I would hate to loose this shrub!

    Reply
    • CL Fornari

      It’s possible one is more exposed to winter sun or wind. Sun can burn the leaves of this plant. It’s also possible the soil and moisture is different, even in “side by side” plants. So check on that. If it’s just some leaf damage the brown ones will fall off and the plant will grow new. If it’s something else, and the plant is dying, you might lose it.

      Reply
  3. Sarah Quackenbush

    Hi there, would like to plant the Otto Lukyen Laurels underneath two trees but the spot only gets about an hour of sun. Would they make it there? In not is there anything else you can suggest for a spot like that? Thank you!

    Reply
    • CL Fornari

      Sarah,
      One hour probably isn’t enough. I don’t know where you live, but one of the lower-growing Rhododendrons, or Skimmia, would be a better choice if you are in a Zone 6 or warmer.

      Reply
  4. Kathryn Johnson

    My 4 cherry laurels are planted in a sunny spot between the houses. Each summer one has to be replaced due to leaves turning brown on one side of the bush and then spreading to the other side. We cut off the brown limbs first. Is there some insecticide we can put around the base so the other side stays alive? I live in North Carolina and our winters have been having cold snaps to 12 degrees Farenheit. Thank you.

    Reply
    • CL Fornari

      I doubt that this is an insect problem. My guess is that it might be sunburn. Cherry laurel do best in filtered sunlight, or morning sun and afternoon shade. If you have to replace one each summer, this is clearly not the plant for that location.

      Reply
  5. Joseph Michael Lubrano

    Two of my Otto Luykens have individual branches that simply died or are dying. First, I thought it was due to the harsh winter of 2018, but it continued up thru mid-summer. Is this a fungus, and if so do suggest say Daconil, or an Oil treatment? Funny though, two others are doing great, could be they are on the sunny side of the house.

    Reply
    • CL Fornari

      Joseph,
      Without seeing the plants it’s impossible to know what is going on. It could be that these branches were cracked by something falling on them, girdled by mice eating the bark, penetrated by a larva/borer, hit with a cleaning product or herbicide, etc etc. Oil treatments are only effective on an insect that they hit, and it’s a waste of your money and time to use a fungicide unless you know the situation is fungal. Clip off those dead branches, and examine them closely for clues when you do. Then wait and see if the damage continues.

      Reply
  6. Laurie G Hancock

    I have a laurel plant whose leaves look like these pictures, but it is the end of July. And it’s been spreading and getting worse. Any ideas? Leaves are turning rust color, no powdery mildew, no spots, no holes

    Reply
    • CL Fornari

      Laurie,
      Without being in your garden and closely looking at the plant it’s impossible for me to know for sure, of course, but I can tell you this: In general, if a plant has browning leaves in mid-summer it’s either that the plant has dried out, has fertilizer burn (too much, too strong fertilizer or synthetic fertilizer applied when the plant is dry), or it’s been hit with something on the leaves such as an herbicide, house cleaning solution, or other product not made for plants.

      Reply
  7. Steve Summers

    Hi there,

    I have schip laurels that are putting out new growth but also have some yellowing leaves which just fall off with a touch. I’m concerned because I lost one last year that started doing this and eventually died. They all seem well-drained but they do have shothole fungus. Would you recommend treating with a normal fungicide, copper fungicide, or something else?

    I appreciate your consideration!

    Thanks, Steve

    Reply
    • CL Fornari

      Steve,
      If it’s the older leaves falling but the new growth is okay the plant is probably all right. If all foliage is yellowing it might be that the soil is too wet. You can spray with an organic fungicide to help with the shothole, but the main thing is to not have the plant hit frequently with water if possible. No automatic irrigation every couple of days….if you’re watering it, once a week in the AM only.

      Reply
      • Steve Summers

        Thank you. I checked the soil and it isn’t very wet, and I’m also not watering but occasionally. I’ll apply the organic fungicide and keep an eye on them. Thank you for your response.

        Steve

        Reply

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