The leaves on all my garden herbs (mint, sage, oregano, thyme, lemon balm) get yellow-brown speckles from late spring, which by late summer almost entirely cover the leaves.

What might this disease (or diseases - the mint looks like rust but I've not heard of rust affecting thyme) be, and how can I treat it? And can I still eat the affected leaves?

Mint Oregano Thyme plant sage plant

  • 1
    Have you checked the underside of the leaves for spider mites? And are your plants in pots (what kind of growing medium?) or in open garden soil? Does that pattern of disease occur annually?
    – Stephie
    Commented Aug 19, 2017 at 20:13
  • 1
    Oh, and of course: Welcome to Gardening & Landscaping SE! Even for seasoned SE users like you, browsing the help center can be interesting. If you need personal help, you might pop into Gardening & Landscaping Chat, see who's hanging out there or leave a message.
    – Stephie
    Commented Aug 19, 2017 at 20:18
  • This is an example where learning to make beds for plants is crucial. These plants are competing with weeds for chemicals with which to make food and energy. Thus they are weak and susceptible to everything that want to use them for energy. Spider mite looks like a possibility. But that isn't what the problem for these plants is...you need to learn to make plant beds...
    – stormy
    Commented Aug 19, 2017 at 21:45
  • It is annual (3 years so far). The mint, lemon balm and sage are in the ground; the oregano and thyme are in an old pot sink (half and half compost and garden soil)
    – aucuparia
    Commented Aug 20, 2017 at 16:19
  • No sign of spider mites that I can see; however there are some tiny (1-2mm) insects that look a bit like miniature grasshoppers and which jump and fly around if disturbed
    – aucuparia
    Commented Aug 20, 2017 at 16:26

1 Answer 1


Those tiny grasshopper-looking jerks are thrips. The spots are from thrips piercing the leaf with their mouths and sucking out the contents. As far as I know, the leaves are safe to eat. I would just wash them to remove the buggers and their frass.

It’s probably an annual problem because thrips can overwinter under plant debris or mulch. Come spring, they’ll start repopulating on your growing plants and the cycle continues.

  • You are so right! Commented May 1, 2020 at 21:40
  • So a year later I find that I may have been wrong in my identification. The pests could also be leafhoppers. (It’s also possible that both frequent my plants. Difficult to tell when they’re so small and move so fast!)
    – xsie
    Commented Apr 12, 2021 at 3:01

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.