Spider Mites

Discussion in 'HortForum' started by Junglekeeper, Sep 20, 2004.

  1. Junglekeeper

    Junglekeeper Esteemed Contributor 10 Years

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    It is often mentioned that a way to control spider mites is to increase the moisture in the growing environment. Does this method work as a result of the mites dying from an inhospitable environment or from them (or their eggs) going into hibernation to wait for more favorable conditions?
     
  2. jimmyq

    jimmyq Well-Known Member 10 Years

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    I have always been under the impression that high humidity creates an unfavorable environment but... never looked any deeper. So, I dunno, I am curious to see if you get a good answer.
     
  3. mr.shep

    mr.shep Well-Known Member 10 Years

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    Hi Junglekeeper:

    I am more interested in the question you did not ask should
    it relate to a specific plant.

    Years ago I learned Mites and Spider Mites to be two separate,
    and distinctly different insects. Today, both insects seem to be
    lumped together almost as one insect for control purposes and
    I feel that is a mistake but perhaps I am missing something.

    I think a lot depends on which form of Spider Mite are we
    talking about in regards to whether humidity can be a deterrent.
    Spider Mites on Strawberries hide on the undersides of the leaves
    and will congregate near the clump whereby the Spider Mites are
    locating themselves in the more humid parts of the plant. Spider
    Mites on certain Conifers will be found on the underside of
    needles far away from the trunk, whereas Spider Mites on a
    Cryptomeria elegans 'Nana' will primarily be located in the
    driest possible areas nearest the trunk. On Cotton and Almonds
    our Red Mite is more of a dust Mite. Whereas, Citrus Red Mite
    certainly is not a dust Mite by any means. In Fruit Trees I was
    astonished to see that the Pacific two spotted Mite is now
    considered to be a Spider Mite by various Universities.

    I think with the above plants mentioned, that humidity is
    not necessarily a factor for a cultural control for this insect.
    The reason why I like overhead watering for many trees
    and specific crops that can be affected by Mites and Spider
    Mites is that we like to wash them off the leaves if we can.
    Forcing a liberation of the insects into the air here makes
    them susceptible to our heat of which many of them will
    simply burn up. We also in part are thinking of liberation
    to make them exposed and easier for attack by their natural
    enemies. Anything we can do without spraying the crop or
    trees will help us in our attempts to prevent the insects from
    laying eggs and regenerating themselves. I know many a
    Cotton grower that when the Red Mite comes in late in the
    growing season that they will go ahead and spray their
    defoliants a little early rather than use a Miticide on their
    Cotton.

    Increased humidity itself is not a suppressant for these
    insects. Granted, we are more likely to see these insects
    in drier climates but Spider Mites, for example, can
    and have shown the ability to live quite well in cool,
    wet climates. One of the more irritating pests on
    Conifers in the Pacific Northwest are Spider Mites.

    Jim
     
  4. Junglekeeper

    Junglekeeper Esteemed Contributor 10 Years

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    In this case we're dealing with mites on indoor plants. I believe there may have been a mix of both black and red mites on different plants. The infestation was in its early stages so I sprayed the infected plants with insecticidal soap followed by a thorough hosing down. Stragglers will be dealt with by spot application of the soap spray.
     
  5. mr.shep

    mr.shep Well-Known Member 10 Years

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    Hi Junglekeeper:

    Well, I know what it was like for me to get rid
    of Spider Mites that came into our home on
    one Orchid I bought for the misses. Indoor
    control is a real pain as the humidity inside a
    home or a greenhouse works against us.

    I am not so sure an insecticidal soap will work
    for you indoors. Outdoors the soap will be
    much more effective. The soap itself does
    not necessarily kill the Spider Mites but
    does disrupt them enough to prevent them
    from laying their eggs.

    For our Miltonias, Oncidiums, Oncidium
    hybrids and Dendrobium Orchids I had to
    use a low grade organo-phosphate to do the
    job for me. The Cymbidiums and Cattleyas
    were not affected by the out break, yet I had
    to spray them also. I sprayed all of the plants
    outdoors more than once, about 3 times, let
    them dry off and brought them back indoors.
    I used a Malathion-Diazinon mixture. The
    problem plant for us was not so much the
    Orchids, the Spider Mites seemed to love
    our Anthuriums much better than they did
    the Orchids.

    Jim
     

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