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Beech tree spider mites?

bédébédé Posts: 3,095
edited September 2022 in Problem solving
Beech tree spider mite is my concocted name.  I am more or less certain that it is a Tetranychus species.  Seen under a low power magnifying glass on the back of the leaves, it is green, active  and acompanied by less active smaller nymphs,  eggs and fine webbing.  It has two spots (In USA, red spider mite is called two spot mite)

The pics show the damage at the moment.  Soon there will be premature leaf-drop.  Hedges  will be bare through the winter.  The initial symptoms are just a dulling of the leaf.  I have caught it too late.

Please wait while I play with the image-adding process.
 location: Surrey Hills, England, ex-woodland acidic sand.
"Have nothing in your garden that you don't know to be useful, or believe to be beautiful."
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  • bédébédé Posts: 3,095
    edited September 2022


    Voila!  The image adding process was not that easy or intuitive, but I seem to have succeeded.

    My question is: how do you control this?  Spraying a hedge with only one-side acess with miticide is not easy, even if you were happy to spray..  I have a large area of beech hedging.  Greenhouse red spiders are supposed not to iike humid conditions, but spraying a hedge with water would also be difficult.  

    I can see it on neighbours' hedges (I haven't told them, I don't want to be the bringer of bad news) and whilst driving about.  I was free from this pest last year, but have had it on and off before.


     location: Surrey Hills, England, ex-woodland acidic sand.
    "Have nothing in your garden that you don't know to be useful, or believe to be beautiful."
  • Pete.8Pete.8 Posts: 11,340
    Spider mites like it hot and dry.
    Now the weather has turned to cooler and wetter they will start to decline.
    They do hibernate over winter and can reappear the following year if conditions are right for it.
    Maybe spray the affected area with water a couple of times a day to increase humidity on dry days.
    As you're probably aware usual bug sprays wont work as the mites belong to the spider family.
    I don't know if a pyrethrum spray may work - it's toxic to many insects, but only works on contact with the bugs - which are on the underside of the leaves so not easy to apply.

    Billericay - Essex

    Knowledge is knowing that a tomato is a fruit.
    Wisdom is not putting it in a fruit salad.
  • bédébédé Posts: 3,095
    I think it's too late this year.  I have in past slowed it down a bit with soft soap solution and also with an emulsion of rapeseed oil and washing up liquid.  Both will suffocate insects and arachnids provided that you coat them - difficult in a hedge.
     location: Surrey Hills, England, ex-woodland acidic sand.
    "Have nothing in your garden that you don't know to be useful, or believe to be beautiful."
  • bédébédé Posts: 3,095
    edited September 2022
    I am a bit disapointed by the paucity of advice.  So am giving this a Dump (?hump) to bring it back to the front.

    There must be many of you with this problem.  Some good ideas will be enough if you have no experience.
     location: Surrey Hills, England, ex-woodland acidic sand.
    "Have nothing in your garden that you don't know to be useful, or believe to be beautiful."
  • BobTheGardenerBobTheGardener Posts: 11,385
    edited September 2022
    I've had trouble with spider mite this year, too.  As @Pete.8 says, the cold and wet will reduce numbers, but if we get a similar year weather-wise, they'll be back next year.  I have it in a greenhouse but am in the lucky position that I can clear all plants out over the Winter and leave the doors open all Winter.
    I've had some luck using SB Plant Invigorator (which works by sticking them in place) but pesticides (or those available to common folk) are a waste of time.
    Good luck.
    A trowel in the hand is worth a thousand lost under a bush.
  • robairdmacraignilrobairdmacraignil Posts: 782
    Just did a quick search for spider mite predators online and this site was one of the first few options that popped up. I remember the sachet type biological control systems were used in greenhouses I worked in before but the product in the link seems to be a bottle that you are directed to just shake gently around the effected area to spread the predator mites that eat the spider mites.

    Happy gardening!
    https://www.youtube.com/user/sustainableveg/videos
  • YnneadYnnead Posts: 250
    https://www.greengardener.co.uk also have biological control. There are others also is you search online.

    London
  • BobTheGardenerBobTheGardener Posts: 11,385
    Unfortunately, the predators available have a very limited range of temperatures they will work at and are so are limited in their use to plants grown under glass.  SB Plant Invigorator is non-toxic and can be used outside.  However, they are very useful (if expensive) in a greenhouse and I have used them several times in the past.

    A trowel in the hand is worth a thousand lost under a bush.
  • bédébédé Posts: 3,095
    Biological control is expensive, and only suitable for a greenhouse.

    For a beech hedge, there are other problems:  what works, what is affordable, how to spray many square meters of hedge, and get to an inaccessible side.
     location: Surrey Hills, England, ex-woodland acidic sand.
    "Have nothing in your garden that you don't know to be useful, or believe to be beautiful."
  • robairdmacraignilrobairdmacraignil Posts: 782
    Just tried looking for other options and this website claims lacewings and ladybugs are also enemies of the spider mite so it may be a help in controlling the mites if you can encourage the ladybugs etc. to settle in your garden. Have been taking steps to encourage predator insects in the garden here for a number of years now and have noticed a particularly good number of ladybirds in the garden this year. Some of the solitary wasp species I have noticed about the place seem very small and could potentially be able to use spider mites as a food source or a host for their eggs but I can't say I have done any experiments to prove this. Just allowing access to water, plants that flower throughout the year and places bugs can shelter seems to have helped the garden here have some ecological balance (along with not using bug killing chemicals).

    Happy gardening!
    https://www.youtube.com/user/sustainableveg/videos
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