Forum home Fruit & veg

Dahlia brown leaves - thrips, virus, something else?

Hello Everyone,

Here are pictures of one of my dahlia plant leaves. It started to go brown on small areas of various lower leaves a few weeks ago, but now has spread. Another young dahlia died a couple of weeks ago, all browned and bitten into. I can get more photos tomorrow if needed but thought I'd start with these. I can't get my camera to zoom in any further unfortunately.

The dahlias are flowering pretty well considering the drought. I can't see any critters. Possibly tiny tiny little white (pinhead size) 'bits' on the back of the leaves. The leaves are crispy dry.

Any ideas what it might be, and how to prevent?  I haven't used neem oil spray and garlic wash this year; I did last year, and didn't notice much browning. They have been fed (but perhaps not quite often enough). Thank you.

 On this photo the 'white dots' are not what I'm talking about, they are something else but look like critters in this photo. Please ignore!


  • My apologies, this post went into Fruit and Veg by accident - I haven't figured out how to move it. I can edit the post but not move it it seems? Perhaps an admin might step in?
  • FireFire Posts: 18,051
    edited September 2022
    Hi, don't worry about the category -  it's not relevant to much.

    Could you give a close up of the white spots? Are the dahlias in the ground or in a pots? Were the plants watered/much?  I know that many people with large beds of dahlias can't water them...   It seems to have been a hard year for dahlia growers across the country as dahlias like damp soil.
  • I will try to get a family member with better camera to take a picture of the spots.

    They are in the ground in clay, get a lot of sun but did get watered ...but not as much as last year as due to ill health. So they may have been a bit too dry over a long period. They haven't flowered as much as I was expecting. And my stalwart (the one I like the least of course) unnamed big magenta, which always does well, has loads of leaves but only one flower all season - gone into survival mode due to hot weather I think!
  • FireFire Posts: 18,051
    It might be one of those years where "it's still alive" is the big triumph. Little white dots might be some kind of fungus. Photos will help.
  • @Fire I've just found this post on the forum:

    Dahlia have yellow dust and fine silk webs, then turned brown and dying


    I don't know how to link to it, but the pictures are exactly like my plant which died - red spider mite - I am sure of it, given the description - there was the tiniest bit of silk web too small to photo and yes yellow dust, but at such an early stage it was hard to be sure until I came across these photos in hyatan's post. It has of course been very dry. I'm going to spray them all and get out the neem oil in case it helps. Thought I'd let you know in case you ever start to see the brown crispy leaves!
Sign In or Register to comment.