Red Spidermite

Discussion in 'Pests, Diseases and Cures' started by adamlewis, May 26, 2010.

  1. adamlewis

    adamlewis Gardener

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    Last night i noticed little red spider like creatures on my tomato hanging basket in the greenhouse.

    Did a little research and found that they are most likely red spidermites.

    This morning took the plant out of greenhouse, checked all the other plants as i went around watering and they are on about half the plants.

    So i am guessing that the hot weather has brought them forth.

    Its my first gardening and its in an old aluminium greenhouse that had been used as storage by previous tennants.

    Everything i am growing is edible, potatos, strawberries, tomatos, chilli, peppers, snap peas, come again salad, spring onions, courgettes, radishes, cucumber, lettuce, herbs, green beans, squashes.

    So i have some questions i am hoping to get help with.

    1. how detrimental to my plants and produce are these pests? Is it safe to eat the produce?

    2. what can i use to control these pests, that will leave my produce edible?

    3. how can i stop the mites spreading? If not for this year then for next, so barriers and prevention i guess.

    4. i have seedlings in the greenhouse and also have seeds i want to plant, how can i do this safely?

    5. i have potted herbs on but don't want to bring them into the house now that they may be infected, do i need to confine everything to the greenhouse?

    6. I have planted a few strawberry runners to make new plant, can i make them safe or am i better killig them off and letting the plant use its energies elsewhere?

    thanks
    adam
     
  2. Marley Farley

    Marley Farley Affable Admin! Staff Member

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    Hi Adam, Oh dear that is not good news mate.. I try to always keep the humidity up in my greenhouse now to try to avoid infestation... You will either need to spray or get a Bio - control.. I have to admit I spray if necessary but I find they do not like humid conditions, they like hot & dry.... There are Bio controls.. http://www.thenaturalgardener.co.uk/red_spider_mite.php
    and here is the RHS blurb on how to control them

    [quote
    Troublesome pest of many plants - particularly indoors or in greenhouse. Information and advice how to prevent and treat red spider mites.

    The first thing that is normally noticed about red spider mite, is the damage that it is either doing - or has done!.
    Red spider mites are so small, that they can only just bee seen - if looking - by the human eye. However, the damage done by these pests soon becomes apparent. The name is a bit of an anomaly - red spider mites are normally green in summer months!

    [​IMG] If you click the image on the left, it will be enlarged enough to enable you to see Red Spider Mites. You will note that they are actually green here. See above. Easier to see, are the cobwebs which are often the first noticeable sign. of infestation [align=left]Red spider mites, are not actually spiders - even though they spin a web! They live from the sap drawn from plants by sucking at the underside of leaves. If left unchecked, they can do substantial damage to plants - even kill them.[/align]
    [align=left]Red spider mites are not easy to control - far better to try and prevent. Red Spider mite attacks a huge range plants - indoors and out. Indoor plants and greenhouse plants are normally worse affected, though Roses, other shrubs, some conifers - in particular Picea varieties - are also susceptible. [/align]
    Symptoms. With indoor plants, the first signs are a general 'sick' look of the plant, with some mottling of the upper leaf surface. This generally happens before the webs or mites are noticed. Plants just stop growing, foliage takes on a discoloured look - pale - sometimes bronze.
    Conifers tend to show sign of browning - as though scorched. This sometimes means that it is too late! Picea varieties - including the blue spruces, and also Picea albertina conica will show a general malaise that need prompt attention if you want to save your prize shrub from certain death by red spider mite.
    Indoor plants - and greenhouse plants - will show a distinct discoloration of the leaf surface. In the greenhouse, Fuchsia leaves will start to look pale - maybe drop off. Same applies to a wide range of plants under cover. It may be necessary to view with magnifying glass to confirm the presence of red Spider.
    Citrus fruit plants are very susceptible - especially in hot weather - indoors or outdoors.
    Vegetable plots are not immune either - beans in particular are prey to the sap sucking mites. Strawberry plants also affected - with no usable spray treatment - bad news for Wimbledon!
    Apple and Pear trees can also be affected - again a discolouration of the leaves - mottled, lightness, or even turning bronze/brown if unchecked.
    [align=center] [​IMG]
    Underside of affected Alocasia houseplant © David Hughes[/align]
    [align=center] [​IMG]
    A closer look! © David Hughes[/align]
    [align=left] Likes and Dislikes : Red Spider mites prefer hot dry conditions. This is why they are particularly troublesome in the greenhouse - glasshouse. The same is also true outdoors on shrubs, Fruit Trees, perennials, vegetables and annuals in a hot dry summer. They dislike damp conditions - and certainly not too happy with cold either![/align]
    [align=left] Prevention: Red spider is a difficult pest to eliminate once an infection has taken hold. This is in part due to the fact that they have several generations in the same infestation, and some chemicals will only kill certain stages of life cycle. Also, Red Spider Mites are capable of building up immunity to most chemicals available. [/align]
    [align=left] So! Prevention is obviously a major asset in the control of this troublesome pest. They do not like damp, humid conditions, together with which regular misting or spraying will actually suppress their ability to reproduce! (Similar to a cold shower?) [/align]
    [align=left] Regular spraying with fine mist of water, in greenhouse and also in hot conditions outdoors is a good form of defence. indoor plants perhaps best taken outdoors for this form of defence, though fine misting on a regular basis will certainly help to prevent a serious attack. Together with this, any form of increasing humidity levels around the house plant - other than for the general well being of houseplants - will help to reduce red spider infestation.[/align]
    [align=left] Cure: Difficult! but, sprays of bifenthrin, or malathion have proved successful. A single spray will not solve the prioblem, for reasons stated above ie only certain age groups within the population are affected. [/align]
    [align=left] Bifenthrin is found in brand names such as 'Sprayday', 'Bug Clear Gun', 'All-In-One Garden Pest Killer'[/align]
    [align=left] Provado Ultimate Bug Killer is also good - as are insecticide containing fatty Acids. [/align]
    [align=left] Maybe a rotation of these chemicals in extreme cases, to a/ prevent an immunity building up, and b/ also to combat the mites which have already built up resistance to one or the other of the sprays.[/align]
    [align=left] Biological control is a realistic method in enclosed situations such as greenhouses. The application is quite important - dependent on correct timing.[/align]

    [/quote]
     
  3. adamlewis

    adamlewis Gardener

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    Well they are on my front door and front wall, a whole house away from the greenhouse so it is some consolation that they are local pests and i haven't imported them in the things i have put in the greenhouse.

    Come to think of this i remember these little fella's being everywhere when i was a kid on my summer holidays... bit different now i have a greenhouse to worry about.
     
  4. adamlewis

    adamlewis Gardener

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  5. pete

    pete Growing a bit of this and a bit of that....

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    Take it from someone who has battled red spider for years Adam, they aint red spider mites.

    I dont think I would worry too much about them, although I dont know what they are, I have seen them before.
    Cant think they have ever been a problem.
     
  6. adamlewis

    adamlewis Gardener

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    thanks pete, so many of the info pages said that spidermites wouldn't be red this time of year... but then they call them red to confuse me.

    have tried to track down what it is exactly as they are all about, if i knew what they were i could work out if i need to do anything. Thanks for putting my mind at rest on the spidermite matter though.

    smiles
    adam
     
  7. Marley Farley

    Marley Farley Affable Admin! Staff Member

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    Phew, you are right Adam they are not spidemite. :yho:
    They are Red Velvet Mites & are common in our gardens especially in Springtime.. They are pretty cool little chaps really as they are always good to have aroud.. They are predators really.. I found you this..
     
  8. adamlewis

    adamlewis Gardener

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    thanks Marley Farley.

    http://www.dgsgardening.btinternet.co.uk/redvelvetmite.htm

    This Red Velvet Mite is of the genera Trombidium one of the many species in the Trombidiidae or Velvet Mite family. The body is covered in fine hairs giving it its 'velvety' appearance. It is usually found in the soil or mulch and feeds on vegetable matter. The larval stage which has six legs, is about one tenth of the size of the adult and lives on blood from animals and sometimes humans. As it feeds it releases an anticoagulant which can cause an allergic reaction resulting in a rash.

    The adult mites have eight legs, they are not spiders nor insects, but a different Order of invertebrates, the Acari, with about 30,000 species of Mites and Ticks. These include the House Dust Mites whoes faeces cause asthma and the Ticks which transmit Lyme Disease.

    The more notorious Red Spider Mite (Tetranychus urticae) which causes damage to plants, is a relative but is much smaller and for most of its life is not actually red apart from a short period in the autumn when they can be an orange-red colour.
     
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