Dahlia unwell?


Hi there,
I will greatly appreciate your help in learning if this Dahlia is experiencing heat-related wilting or is it as you say in this post a fungal disease: https://www.torontomastergardeners.ca/askagardener/dahlia-with-drooping-leaves/?
I really appreciate your help and guidance.
Thanks so much!


At first glance this appears to be heat-related yellowing of the leaves rather than a fungal disease such as Verticillium wilt, which, as its name suggests, does cause stems to wilt and droop, and that doesn’t appear to be evident from your photograph.  If you have not been fertilizing your dahlias, this is something you could consider, as the post that you have included suggests, making sure that you do not over-fertilize this late in the season.  Also, be sure that you are watering consistently, because irregular watering – both overwatering and underwatering – can show up as yellowing of leaves.  If your dahlia is in a container, given the extremely hot temperatures recently, you will need to monitor it closely.

Do keep an eye on your plant.  If stems begin to die back and leaves curl, wilt and drop, these are signs of a fungal disease.  In this case, you will need to get rid of the plant and be sure that you do not re-use the soil for dahlias or other plants that are susceptible – Verticillium wilt is a soil-borne fungal disease that remains in the soil and can re-infect other plants.

August 28, 2021