Eco friendly pest control

dahlitsaFebruary 12, 2008

Last year my hollyhocks were turned into lace. They would keep coming back but never got to bloom. I think I sprayed them with soap and water. What can I use?

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rhizo_1 (North AL) zone 7

Your description sounds like an infestation of the hollyhock (or hibiscus) sawfly. These small caterpillar-like larvae turn the large leaves of their favorite host plants into....lace!

Sawfly larvae are pretty susceptible to insecticidal soap applications, but you must get the product ON the insects. They tend to congregate on the underside of the leaves. Neem oil is also effective against them.

    Bookmark   February 12, 2008 at 4:15PM
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Whether your soapy water spray was effective or not depends on what was used and how much. Insecticidal soaps need to be made from soaps made from animal or vegetable fats, not detergents made from petroleum, and a mix of 1 teaspoon of that soap in 1 quart of water is all that is needed, but the spray must contact the target because it has no residual action, although detergent sprays can harm the plants.

    Bookmark   February 18, 2008 at 8:05AM
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i think your problem may have been misidentified. japanese beetles will not leave hollyhocks alone (in my experience). they skeletonize the leaves, turning them into "lace," and i have not found insecticidal soaps effective against them (or other hard-shelled beetles).

instead, i spray the beetles most mornings (while they are sluggish) with something containing imocloprid -- bayer's rose and flower spray, for example. when that lost its charm, i decided to stop growing hollyhocks, much as i love them. since i am a half-hearted sprayer and i found i could not keep the plants looking good, i struck them from my list (sigh).

    Bookmark   February 26, 2008 at 3:43PM
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Try to entice birds to the garden too.
I find hollyhocks look good at first, and later succumb to those beetles or whatever. Just pull them out or cut them down when it gets to that point. Enjoy them in the early part of the season. If you can, you can pick off or knock off the bugs if you see them.

    Bookmark   February 27, 2008 at 10:26AM
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With Integrated Pest Management you do not start with the most toxic substance there is to control any pest. I have seen many times that the soil plants are growing in can be a major factor in pest control. If that soil is a good, healthy soil well endowed with organic matter so it is evenly moist but well drained and has a balanced nutrient load the plants growing in that soil will be more resistant to insect pests. Plants decimated by insect pests most likely are growing in a soil that needs attention.

    Bookmark   February 28, 2008 at 8:53AM
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kimmsr, the soil in my garden rates "beyond optimum" in all categories on my soil tests. it is as rich as chocolate cake. it does a disservice to inexperienced gardeners to suggest that "if only" their soil was better, insects wouldn't eat their plants. c'mon.

bugs happen. we have to decide whether there is a reasonable control or whether pest populations are such that we should forego certain ultra-attractive species. i'm not going to assume that you are referring to imicloprid as "the most toxic substance there is," since that is so far from the truth that it would prevent me from thinking of your posts as credible -- and i have always thought of you as an important contribitor to these forums.

by the way, i tried several alternate methods before resorting to an effective spray that is easy on beneficials. I did not spray the whole plant, but targeted individual beetles. the superabundance of butterflies, hummingbirds and dragonflies in my yard speak to my extremely conservative use of controls, chemical or organic (many of the organic ones being among the most poisonous.)

    Bookmark   February 29, 2008 at 1:09PM
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If your soil is "beyond optimum" in all categories and the nutrients are not in good balance, ie you have some in much larger numbers than necessary, even though it looks like rich chocolate cake (which by the way is not a really healthy food) then the soil is not healthy. Nutrients not in good balance can interfere with the uptake of other nutrients which will result in a plant not being strong and healthy, and often more attractive to insect pests.
If trying to get people to think about the soil they have is a disservice I am truely sorry, but the soil that plants grow in is the single most important part of the garden.

    Bookmark   March 1, 2008 at 8:37AM
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rhizo_1 (North AL) zone 7

kimmsr hasn't embraced the fact that some plant species are documented hosts for specific insect or disease pests. This is true no matter how healthy and balanced the soil system may be. Hollyhocks are just one of those many plants.

However, it is also true that the healthier the plant, the more likely it is to be able to recover from major pest damage. Also, it is a fact that plants that are in 'stress mode', whether it be from heat, drought, over watering, poor soil, etc. tend to be the first to be attacked by everyday garden pests, and to suffer severe damage.

But it is still important to remember that host plant relationship. I try to avoid known hosts for certain insects and diseases. That takes some research, but it sure it worth it. I also adhere to control measures that have very little affect on the huge number of predatory and parasitic critters that help keep the pest population under control.

Since our original poster did not mention the presence of beetles of any kind, I still assume that her plants were skeletonized by the sawfly larvae, which hide very effectively on the underside of the leaves. Lots of folks complain about the symptoms without ever even seeing those little green larvae! But if the sawfly doesn't get 'em, the Japanese Beetles will! ;-)

    Bookmark   March 3, 2008 at 2:05PM
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The only problem I have seen with Hollyhocks in my garden is "rust" on the plants that grow in the too rich soil. The Hollyhocks that grow in leaner, meaner soil do not get the rust and do not have any sign of the sawflies or Japanese Beetles even though some other plants may have them.
Far too many people think that pests and diseases are normal in plants, but they are not anymore than diseases and parasites are normal for human beings. Provide an environment that will grow a strong, healthy plant and you will see a large decrease in plant pests and diseases. It is really that simple.

    Bookmark   March 4, 2008 at 6:49AM
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