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onmiown3

Spider mites?

onmiown3
19 years ago

I think I have spider mites on two tomato plants and now my fall peas, but I keep reading that the mites are very tiny. One site said mites are about the size of a 10-12 point font period, like the one at the end of this sentence.

Mine are about the size of a 24-28 point font period. Also, I keep reading that they only live on the underside of leaves and mine like anywhere on the leaf.

My bugs start out as greenish eggs on the underside of the plant leaf. When they hatch, they are white and only the size of a 16 point font period. As they get older, they turn reddish and get much bigger. All the leaves they are on turn yellowish and begin curling up.

I've applied three applications of Sevin over the last month and it's not killing these things. Can someone help?

Thanks,

Kim

Comments (17)

  • _sophiewheeler
    19 years ago

    Sevin is an insecticide and will kill off all of the beneficials that munch on spider mites, but it won't kill spider mites because they're not insects. They're acarids, and you need a miticide to kill them. Miticides are usually very expensive for good targeted control or very very toxic for cheap scorched earth policy that kills just about everything. The easiest way to kill spider mites is to disrupt their breeding cycle by hosing off the leaves every day with a sharp water stream from the hose. They like it hot and dry, and this will keep them washed off.

    But, your infestation doesn't sound like spider mites to me. More like flea beetles or something else. If you can see them, they aren't spider mites. The telltale diagnostic for spider mites is to take a white piece of paper and put it under a leaf and rub. If you get tiny black or red flecks, those are spider mites. The leaf will feel "gritty" like it has sand on the underside and you will occasionally see the webs that they weave. The leaves have a tiny yellow stippling on the topside that comes from them sucking out the juices from the underside of the leaf.

    Here is a link that might be useful: Spider Mites

  • Kimmsr
    19 years ago

    Carbaryl (Sevin) is the most toxic thing you could have used and if one application did not eliminate the insect population of your yard more won't either. Never go to the most toxic product you can find first, always start with the least toxic product that has the potential to solve your problem. Would a sharp water spray have controlled these pests? Most likely. Would insecticidal soap have done something to control them? Probably. Would something with Neem Oil in it have done something to control them? Maybe. A better choice than the carbaryl would have been something with pyrethrins in it, not quite as toxic to you, anyway.

  • onmiown3
    Original Author
    19 years ago

    Kimmsr,

    Gee, your tone is coming off as scolding to me, and I was just asking for advice. I appreciate the information, it could have been given more tactfully.

    I am new to gardening so I went to my locally owned and operated greenhouse and described my problem to them and Sevin is what they recommended to me.

    I though I was taking good, professional advice when I used the sevin, but apparently not.

    I did try using a sharp spray of water on Friday on all infected plants and the buggers did not budge.

    Kim

  • jean001
    19 years ago

    Let's go back to stage one to find out specifically what pest you have on your plants.

    You've done your homework in reading up about what mites should look like. But, as you stated, your critters don't match that.

    Oops.

    I just realized that you posted photos on the Garden Clinic. And if those are the plants you're asking about, the answer is aphids. Lots and lots of them! Seeing the critters helps considerably :>) Thanks.

    OK, let's go from there.

    As a beginner you misinterpreted what you saw. But that's okay because all of us learn by doing. (Beyond that, *all* of us were beginners at one time.)

    Then, too, the first advice you received was incorrect, a far too common occurrence when someone suggests treatament but hasn't seen the potential cuprit up close and personal.

    Your critters weren't affected by Sevin because that stuff is for chewing pests. As for the water spray, it will work if you direct it onto the live aphids (the colorful ones) whereas it's unlikely to budge the cast skins.

    Folks should go to your other post for the rest of the story, w/pictures.
    http://forums.gardenweb.com/forums/load/pests/msg1015085316109.html?1

    Good luck with your garden. And keep asking questions.

    Here is a link that might be useful: your post with pictures

  • Kimmsr
    19 years ago

    Onmiown, sorry if that sounds like scolding, I really did not mean it to. Most garden centers will recommend Carbaryl as the first choice for any problem, and I have been there when it was suggested for black spot on roses. Jean, carbaryl is a contact as well as an ingested poison and also a cholinesterase inhibitor. Very broad spectrum and fatal to a large number (about all except some Colorado Potato Beetles) of insects.

  • onmiown3
    Original Author
    19 years ago

    Kimmsr,

    Thanks for the clarification.

    Here I thought my locally owned greenhouse would be more careful on what they recommended and I was wrong. Not only did they give me a product that DID NOT treat the problem I thought I had, but it doesn't treat my actual problem either.

    I've found another locally owned place with lots of oranic pest controls and fertilizers. They'll be getting my business from now on.

  • billmixer_gmail_com
    12 years ago

    I've had spider mites on my tomato plants 2 years in a row now and they are a very frustrating pest to have. Tried hosing, 5 doses of Neem Oil and their still slowly destroying my plants. I read somewhere that they lay so many eggs that they can "outbreed" the insecticide.

  • Kimmsr
    12 years ago

    Spider Mites, during hot, dry, weather, suck more of the plants sap which acts as an aphrodisiac so they breed more producing more Spider Mites. Misting of the affected plants can raise the humidity enough to slow the wee buggers down, hosing is not likely to do that, although it may dislodge some of these wee buggers.

    Here is a link that might be useful: Spider Mites

  • IpmMan
    12 years ago

    Sevin is hardly "the most toxic thing you could have used". Look up the LD50 of Sevin. Nicotine, Caffeine, and Tylenol all have lower LD50s than Sevin. (The lower the Ld50 the more toxic something is) But as said it definitely is one of the worst things you can have used for spider mites. I think you should find a new garden center. If you mix 1tablesopoon vegetable oil and 1 tablespoon of pure soap in 1 quart of water and spray this on the mites they will die. Don't use this if the weather is hot and sunny or you will burn the leaves. If you can't wait for a couple of cooler days cut the formula in half and spray late in the day.

  • Kimmsr
    12 years ago

    Carbryl is classified as moderately to highly toxic. It is not something one practicing Integrated Pest Management should use as the first product in an attempt to control a pest.

    Here is a link that might be useful: Carbryl

  • IpmMan
    12 years ago

    Who said Sevin was a first choice. I have actually never used it, not because it is very toxic but because of the development of other more narrow spectrum choices. I was merely stating a fact that it actually is less toxic (according to the LD50 scale) then such things as Tylenol.

  • rhizo_1 (North AL) zone 7
    12 years ago

    C'mon, IPMman. You've got to go by other variables for toxicity than the LD50! Look at acute mammalian toxicity, bees, butterflies, assorted wildlife, earthworms, modes of exposure, and on and on.

    I recall a newspaper article written some time ago, when the man in charge of mosquito abatement for Beaufort County, SC commented that the ULV malathion he used for overhead spraying was so safe on the LD50 scale that people could drink it. Granted, he was ignorant, but it brings to mind that we need to remember that one should never ever ever use LD50 as the only criterion for measuring the relative safety of any chemical.

  • Kimmsr
    12 years ago

    The LD50 refers to the acute toxicity of some substance. It tells you very little about the long term affects that substance might have on someone. There are studies that appear to indicate that children exposed to relatively high levels of Carbryl at an early age have more behavior problems and lower IQs then children raised in similar environments but not exposed to Carbryl. Should that be cause for concern?

  • rhizo_1 (North AL) zone 7
    12 years ago

    IPM man, I agree with your statements. Good sound common sense should be able to be applied in generous doses when it comes to chemicals, 'organic' or not.

    However, I think the fact that carbaryl is a cholinesterase inhibitor should automatically put it on the list of chemicals that are too dangerous to use. Such chemicals can wreak havoc on the body systems of us two legged human types.

  • dave_k_gw
    12 years ago

    Struggling with spider mites on Orange Jewelweed (Impatiens capensis). I too tried stronger material first, in an effort to recover mite damaged plants. No luck. The mite infestation seems to be more noticeable after hot dry weather, to which these plants are very sensitive. Lately I've been using insecticidal soap about once a week, and spraying water under the leaves with a hand spray bottle daily. Still alive, we'll see.

  • rhizo_1 (North AL) zone 7
    12 years ago

    Let's not lose sight of the fact that healthy plants can tolerate some spider mites. Believe it or not, there are quite a few natural controls out there to help us in the form of predatory mites, some thrips, some predatory beetles, and more. It pretty normal for there to be an increase in the mite population after strong pesticides are used.

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