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Dahlia disease help

My border double flowering yellow dahlia has developed brown and crispy leaves, then the top stems died.  There are signs of it recovering but this year there are very few flowers despite my regular watering during the hot months.

Last year, I had the same problem occurring to by velvet red dahlia plant which was in a large pot.  This year, it also happens to 2 pots.  What is the cause and how can I rectify it?

I would be grateful if you can help.


  • hyatanhyatan Posts: 9

  • hyatanhyatan Posts: 9
    Above are the photos of what it looked like in August 2022
  • BobTheGardenerBobTheGardener Leicestershire, UKPosts: 11,368
    Spider mite damage.  If you look closely at the growing point, you will see some webbing.  This tiny dots running along the threads is the mite.  Quite a few are seeing it this year due to the hot weather.
    A trowel in the hand is worth a thousand lost under a bush.
  • HeartinthedirtHeartinthedirt Liverpool Posts: 284
    I've had a similar problem with a potted one, is there hope for it coming back next year?
    It's knowing what to do with things that counts - Robert Frost
  • BobTheGardenerBobTheGardener Leicestershire, UKPosts: 11,368
    edited 20 September
    Yes :) Although a few may overwinter on the plant, most will be killed by the weather.
    Infestation can kill a plant, but that usually only happens to neglected indoor ones.
    A trowel in the hand is worth a thousand lost under a bush.
  • c_watkinsc_watkins MonmouthshirePosts: 48
    @hyatan I've just been looking for info about this and your photos have helped a lot. I'm going to spray neem oil all over and esp underneath the leaves to hopefully see them off until the first frosts. Last year I used neem oil and garlic wash in sprays all over and didn't get much mite trouble at all, but this year I haven't been able to and they've been attacked. Keep preventative spraying would be my advice! Good luck with it all and for next year. 
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