I have tried isolating stemphylium and alternaria on PDA several times but unfortunately I am unable to get proper results. The method I have followed is surface sterilization of the diseased leaf portion by HgCl2 and 70% Ethanol and then placing it on petri dish containing PDA and further incubating it at 28 degree for nearly 7-10 days. After incubation a whitish powdery growth is seen on the plate. Alongwith I hav attached a few images of the fungal growth pattern as well as a microscopic image. Please tell me why m I facing this problem? Also suggest me some other media or any other changes I need to do in my protocol.
Dear Pragati Randive thank you for your interesting technical question. As an inorganic chemist I'm not an expert in this field. However, I would like to suggest to you the following relevant references which might help you in your analysis:
1. Management of Stemphylium Blight of Onion by using Biological Agents and Resistance Inducers
Data Management of Stemphylium Blight of Onion by using Biologica...
2. Isolation and identification of fungal pathogens in onion crop from Perambalur District, South India
Article Isolation and identification of fungal pathogens in onion cr...
This article is freely available as public full text on ResearchGate.
Not sure what you mean 'by proper results' - pure sporulating cultures that allow you to confirm the identity of the fungus? I think surface sterilisation with HgCl2 and 70% Ethanol is a bit harsh - Sodium hypochlorite is more usual. Try incubating the diseased material in a damp chamber, and transfer spores to PDA.
Try different light regimes, and different light, e.g. NUV - [near ultraviolet] light. Also reduce richness of agar - PC [carrot] A or half strength PDA..
Use sodium hypochlorite for surface sterilization of sample leaves.
Stemphylum: colonies on PCA were grey to brownish
grey, formed concentric rings, were flat, entire, and circular,
attaining a diameter of 50 mm after 7 days, with sparse aerial
mycelium. Mycelium was immersed and superficial, subheadline
to pale brown, branched, septate, smooth, and 4–
6 μm diam.
https://www.google.com/url?sa=i&url=https%3A%2F%2Flink.springer.com%2Farticle%2F10.1007%2Fs13313-016-0463-y&psig=AOvVaw3vdNIu5DF2lc22ACv5siYe&ust=1635950976692000&source=images&cd=vfe&ved=0CAsQjRxqFwoTCKCkxcj2-fMCFQAAAAAdAAAAABAJ
- Badges
- Science topic