Hello again,
I deleted the topic because the gazania problem was not caused by any fungus, however, just in case someone had the same problem, I leave it with the updated info.
We noticed we had the same stains on Zinnia and Aster, and the leaves also got "splitted" in a transverse plane, but in these cases I saw no hyphae with the microscope. We realized that this is caused by some kind of minator insect (or arachnid).
I'm doubtful about the fungal nature of the filaments I saw in Gazania. Also, the supposed sporangia may not be fungal structures. I'll keep watching.



Hello everyone,
Two weeks ago we detected some Gazania plants (at stage III after germination) which had some kind of blight as you can see in the pictures: the colour is dark grey, at first it involves the tip of the leaf, and then the stain gets bigger and bigger, but there is a clear and straight boundary between healthy and ill tissue. The upper and back sides of the ill parts of the leaves splitted easily. Also, I could see a mycelium over the upper side of the leaf using a manifier.
I took some samples and I watched them at the microscope. I saw what I think they are hyphae, but I couldn't see any reproductive structure. I put some damaged leaves in a Petri dish with water and I waited some days (I have a quite rudimentary lab to do these kind of analysis...). Then I prepared new samples to see at the miscroscope and I could see also the same hyphae and what it might be round 16 ?m diameter sporangia, but I'm not able to identify these structures. Could you please help me?

THANK YOU VERY MUCH!!!