photo des spores

dear Bernard

In my opinion, you should provide much larger spore photos to clarify your fungus. With oil immersion it is then usually possible to see the nuclei in the spores. Typical D. tuberosa has 4-nucleate spores, while Sclerotinia sclerotiorum has 2-nucleate spores. Perhaps also a macrophoto would help. I do not know D. filipendulae personally. Were the 8 spores all of the same size within the asci?

Zotto

Merci pour votre réponse rapide.
La majorité des spores observées sont biguttulées. est-ce un bon indice ?
BB

The guttules (oil drops, LBs) are much more distinct than the nuclei. You need to look with oil immersion and to close a bit the aperture. Often helps vital staining with Lugol or Cresyl blue. But this is difficile because the spores may finally die, and then the nuclei are not further visible.

Zotto

Désolé ! je ne dispose pas d'un matériel micro suffisamment performant pour voir ces détails.

What is your equipment? To see this needs only a 100x oil immersion objective of medium quality, a 10x widefield ocular and living material.

Zotto

Bonjour Bernard et Zotto,
La réception d'une partie de la récolte m'a permis de constater que les spores sont bien binucléées.

Un autre élément plaide en faveur de Slerotinia slerotiorum : la réaction positive de l'excipulum à l'iode (lugol).

Amitiés à tous

Thanks, Michel. I wish to add that the idea of Dumontinia ulmariae is not that bad, the diagnosis in the key by Holst-Jensen would fit quite well (except for the spores being "uniguttulate"), but the number of nuclei is not mentioned. Moreover, with the key of Schumacher & Holst-Jensen (http://biologi.uio.no/bot/ascomycetes/Sclero.key.html) the present find keys as a Sclerotinia:

Dumontina: Apothecial outer excipulum composed of brick-shaped cells (textura prismatica) and an inner zone of loose hyphae embedded in a gelatinous matrix.

Sclerotinia: Apothecial outer excipulum of globose to hexagonal cells.

However, I am generally unable to confirm this key because the excipula of my collections of D. tuberosa (spores 4-nucleate) do not at all fit to that key, and I therefore prefer to merge the two genera.

Zotto

Merci Zotto pour ces nouvelles précisions et commentaires.

Nothing is easy, then , which I had already guessed! :-P

As for Bernard's find, the ectal excipulum is a quite perfect textura globulosa and I did not notice any gelatinous matrix embedding loose hyphae.

Amitiés
Michel

I collected today fine D. tuberosa (with Anemone, Ficaria and Aegopodium around) but I have no microscope here in Bavaria.

Will to have drying it and examine when at home.

Zotto