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Why Did My Plant Die?

This is the place to read Ketzel's advice to readers' most harrowing gardening challenges from whitefly eradication to weed killer application, lawn alternatives, and bulb care. No matter where you keep your garden, check out the resources available to you locally. Find a shady spot and maybe a helping hand in the Talking Plants Gardens and Arboretums map of the United States.

Archive
Here's the Vast and Cavernous Archive of Enquiry that the Doyenne has already answered. Good clean fun for the whole family.

This week's questions:

  • Aphid Invasion
  • Moles and Voles Galore
  • Purple and Silver Leaved Shrub
  • Quick Hedges
  • Weedy Bank
  • Indolent Raspberry
  • Winged Elm Dropping Wings
  • Rosemary and Basil
  • Artemesias

    Aphid Invasion

    Dear Doyenne,
    They gobbled up both of my coral honeysuckle plants and they continually attack the roses. The usually prescribed remedy, spray them with water, is absolutely ineffective. The ladybugs I imported weren't big enough eaters. Poison didn't stop them. I'm back to Dr. Bronner's Peppermint Castile soap, and I'm not sure yet if it is working. There are black specs on the buds on the honeysuckle stumps (I had to cut them down entirely). I plan to sprinkle kelp around their chosen plants -- I've heard that may help. I have yarrow and other plants that are supposed to attract the bugs that prey on aphids. Do you have any suggestions to prevent or keep up with aphids in coastal Southern California?

    Thanks,
    Marianne

    Marianne,
    Yes, the common wisdom is to rinse affected plants with a strong spray of water, and no, it doesn't always work. Folks also brush them off if their numbers aren't daunting but clearly, you're way past that.

    Before I go into the litany of options, I'm obliged to point out that from a plant health perspective, aphids really donít cause that much damage (except they do transmit disease). They tend to be transient pests in the garden and more of an aesthetic nuisance than anything else. And they do that very well.

    Now for some options:

    1) For enhancing the effectiveness of ladybugs, I've heard good things (and have no personal experience) with a product called BugPro. It's said to attract ladybugs for the purpose of egg laying; the hatchlings then devour the aphids before they fly away. You may have noticed how difficult it is to attract beneficials into urban areas. The reason is the lack of diversity in our plant communities. Even an island of diversity (e.g., a garden bed) in a sea of monocultural lawns is not going to help much.

    2) The preferred fallback for aphid control continues to be insecticidal soap, nicotine spray or pyrethrins. The latter two are more controversial because of their high toxicity, but for what it's worth, they are natural pesticides and therefore not residual in the environment.

    3) Cutting the plants back doesn't work. I learned this the hard way. All you'll get is tender new growth that will, of course, be infested with aphids. And in the process, you'll have weakened the plants further. Once the stems and older leaves mature they will be pretty unattractive to aphids.

    4) I have no idea what kelp is supposed to do. Of course, there are lots of dot-com sites (dot-con?) that swear by its effectiveness in aphid control and refer to studies at the U of Maryland and at Clemson. I understand from folks in the field that there are no peer-reviewed publications on kelp and aphid control anywhere in the literature. So wherever this information came from, it certainly wasnít scientists. All kelp is good for is as a source of organic material.

    5) Happy, healthy plants are the best defense. Stop chopping them down, build up organic materials in the soil via mulching, give them plenty of sun (helps toughen the cuticle) and water, and if your aggravation levels continue to go off the charts, consider alternatives to honeysucke and roses, both notorious aphid traps.

    It's a jungle out there! KL

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    *****

    Moles and Voles Galore

    Dear Doyenne,
    Our Goshen, Connecticut yard and garden was covered with snow until the first week in April. (True. We have a saying in Goshen: We don't use our snow until it's two years old.) Snow cover is great for moles. Snow gone; at least 50 mole eruptions. My wife wants to spend $200 to get rid of them. There must be an easier, cheaper way. I say let moles eat all the grubs, then they will go away by themselves.

    Thanks,
    Barney

    Barney,
    I'm with you. Despite the best advice and best of intentions, there is no permanent way to prevent mole damage. Nature abhors a vacuum -- as soon as the existing moles are removed, new ones will take their place. Also, moles tend to be transient visitors to any one piece of property; give them some newly disturbed soil and they'll burrow themselves into ecstasy.

    Let's face it: those of us who like our lawns weed-free, insect-free and monocultural (i.e., all grass) are destined to live in high-maintenance, chemical-laden nightmares. So if the area you're describing is grass only, any chance of a nice shrub border to take up some of that space?

    Best, KL

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    *****

    Purple and Silver Leaved Shrub

    Dear Doyenne,
    We have a moderate-sized patio on the East side of our home in Eastern Washington (Richland). Currently we have a 6 foot pyramid shaped evergreen, but my husband wants to remove it. He would like a flowering, branching tree, and I don't want something too big.

    Thanks,
    Susan

    Susan,
    Though there are umpteen choices, one large shrub immediately come to mind. Cotinus coggyria 'Royal Cloak', the smokebush, is a multi-stemmed, 15' shrub with dark purple leaves that turn a stunning orange in fall. It spends late spring and summer covered in a fluffy, pink haze (the so-called smoke). Another textural delight that has good shape in winter is the rosemary willow, Salix eleagnos (don't worry, this is a shrub, not a tree). It grows 6-10' high and wide and flickers all season with tapered, silvery leaves.

    Best of luck, KL

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    *****

    Quick Hedges

    Dear Doyenne,
    We live in a suburb of Memphis, TN. I want to plant a natural fence around our 200 foot long property. I'd like an evergreen, that can be in full sun, grows FAST and full, is not messy that will provide a wind break, noise break, roaming animal break, provide a screen view, does not require watering -- can handle rainy, or dry seasons, cold and hot weather and does not mind humidity.

    It was suggested to us to use Leyland Cypress and plant them every 5 feet.

    Thanks,
    Sheila

    Sheila,
    You don't want much, do you? Leyland Cypress are fast growing, but you trade that off for plants that are disease prone, weak-wooded and short-lived. The fact is, any hedge or screen worth having over the long haul is going to take a little time getting up to speed. One suggestion that comes to mind is Osmanthus heterophyllus 'Purpureus' which will reach 12' in 5 years. It's drought tolerant, takes full sun, is completely hardy and relatively deerproof. See if you can get your hands on a bunch of two-gallon pots, then plant them every 5'. If no one carries the plant locally, you might ask for comparable solutions at some of the better nurseries. I know you can mail order this osmanthus, but I suspect that will be prohibitively expensive to cover the amount of ground you have in mind.

    Best, KL

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    *****

    Weedy Bank

    Dear Doyenne,
    I live near Pittsburgh Pennsylvania. I have accepted the unique challenges of gardening in my area. We have rampant briars (wild roses are the worst), clay and shale soil, deer as abundant as barn cats, and, particularly where I live, buried fill that yields up unique surprises wherever I dig (once I found part of a tombstone). In spite of all this, and armed with little more than a good pair of gloves, a paper clip and a ball of string I have managed to install a series of successful gardens around my house. I'm really tired.

    My next project is to clean up a steep shaley bank that descends from the level of our driveway to the level of our meadow. There is already landscaping along the top of the bank and my herb and vegetable garden lies at the bottom. The bank is covered with goldenrod and asters, fleabane, raspberry, burdock, and particularly bindweed. I'm no horticulturist but I'm pretty sure the roots of all these plants go all the way to Hell. I am alternating between wanting to eradicate all growth on this bank and start over with less invasive wildflowers, and wanting to simply get rid of the bindweed and the burdock and about one third of the other stuff so it's not pushing my garden fence over. Whew. Any suggestions?

    Laurie


    Laurie,
    I'm exhausted just reading your note. It sounds like you need my advice like a hole in the head, since you're doing so well already. But if I were you, I'd just get rid of everything on the bank and go with the less invasive wildflowers. Seems the only way to deal with big out of control areas is to take the bull by the horns (a technique you're well-versed in); otherwise you might end up making more work for yourself in the long run. Why not try cooking the plants under several layers of clear plastic?

    UNenviably yours, KL

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    Indolent Raspberry

    Dear Doyenne,
    I have planted a raspberry bush, two years ago, but it is not doing much. Any recommendations for pruning fertilizing or soil treatment?

    Thanks,
    Peter

    Peter,
    If your plant hasn't done anything for 2 years, my guess is that it has a crummy root system. I would dig it up and really get into that inner root ball. It's possible you'll see a 4" square root mass that formed when the plant spent too much time in a 4" pot. If this is the case, cut the roots apart and spread them out, replant, and tend it carefully with regular water and a good mulching.

    Another possible problem might be competition from nearby weeds, grasses, etc. If there are plants encroaching on your raspberry, remove them (preferably by mowing; digging might disturb the raspberry), then mulch with wood chips or coarse organic matter.

    Hope this helps, KL

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    Winged Elm Dropping Wings

    Dear Doyenne,
    I am not sure if you answer questions about trees as well as plants, but here goes. We have a Winged Elm and every spring it not only drops its seeds, but it drops the tips of all of its small branches as well. We think it does this every spring, so we are figuring this is normal, but why the whole tip of the branch?

    Thanks,
    Elizabeth and Alex, Atlanta, GA

    Elizabeth and Alex,

    Several things could be going on here. First off, it could be that the tree grows a little too exuberantly in your warm Georgia springs, so that when the heat of summer comes it feels like it has taken on more than it can support (hence, it bails on the tips). That happens here in Oregon with a number of trees (oaks, elms, etc.).

    A more likely explanation may be that the soft tips of the branches are not hardening off before winter; consequently, they die back and fall in spring. The question is, why are the trees (which are native to Georgia) continuing to grow into the late winter? If they are being fertilized in the late summer/early fall with high nitrogen, then this could cause them to delay dormancy and continue growing. Light pollution could also be a factor; if your tree is exposed to artificial lighting via street lamps, it might perceive that the days are still long and that the nights are still warm. That would also delay dormancy.

    Finally, there's a chance your tree was water-stressed during the summer months. Again, with the tips being so tender, they would die first, but not fall until spring. Here's hoping one of these answers apply.

    Best of luck, KL

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    Rosemary and Basil

    Dear Doyenne,
    During the summer I always plant rosemary and basil in individual pots. Neither have done very well -- in fact the rosemary has not grown from the nursery bought plants. The basil has done well but seems to peter out sometimes after the middle of the growing season. Any suggestions?

    Thanks,
    David, Pittsburgh, Pa

    David,
    Let's start with full sun. Trusting you're giving your plants at least that, let's move on. Rosemary needs excellent drainage and air circulation to thrive in your climate. It also has large roots, so the bigger the container, the better. Basil is best treated as a vegetable crop, much like tomatoes. It also needs a large pot, though this herb prefers richer soil and ideally, a weekly feeding . I recommend liquid fish emulsion.

    Better luck this year, KL

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    Artemesias

    Dear Doyenne,
    A couple years ago, I planted 3 artemisia absinthum (wormwood) in a box, and they'd been doing well. This past fall, I cut them back twice. This spring, as everything was budding and leafing, one of the three plants put out great little handfuls of new silvery leaves (the one furthest away from the sun, interestingly) the other two, however, seem stuck in that grey bud zone, and when I gently pried at the plant's stalks the ones not leafing seem to wobble a bit more in the soil than the one that is leafing.

    Should I dig up these apparently dead plants, or should I give them some more time to put out some leaves? While it's easy to get some new plants, I'd rather give something that in the past couple of seasons has been so successful a bit more of a chance before I throw in the towel.

    Thanks for any ideas,
    Isabeau

    Isabeau,
    Artemesias are not normally long-lived plants (3-5 yrs), and have a habit of dying out after several seasons. They're also susceptible to a number of pests, and my guess is that your plants are wobbling because root weevil larvae have been feeding on their roots. I know you don't want to trash the plants, but that's my best advice: buy new artemesias and treat the beds with predatory nematodes. You can pick the nematodes up at most garden centers, and apply them through a hose end sprayer in April and again in October (the months that the months that the larvae are most active). Let's face it: old artemesia look like hell!

    Best, KL

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