Hi: If you want to test the pathogenicity of the fungus in the petri dish, first think you should know the conditions of the spore germination of the fungus (humidity and temp) and spore concentration to have a good infection, also you must know the ideal light  period ,because some pathogens required light to have a good infection.

DearMaizan Ismail

Pls. find the attached files

http://www.nature.com/articles/srep25591

Page 170 in: Noreen G. Dowling, Stanley Marshall Greenfield, K. S. Fischer. 1998. Sustainability of Rice in the Global Food System.  University of California, Davis. Pacific Basin Study Center, International Rice Research Institute Int. Rice Res. Inst.,Pp.404. ISBN 9712201074, 9789712201073

http://www.apsnet.org/publications/PlantDisease/BackIssues/Documents/1989Articles/PlantDisease73n06_459.PDF

http://www.sciencedirect.com/science/article/pii/S2095177915300150

http://www.jove.com/video/3064/aseptic-laboratory-techniques-plating-methods

http://www.doiserbia.nb.rs/img/doi/0354-4664/2010/0354-46641003611Z.pdf

http://www.trepleieforum.no/foredrag/schubert_03.pdf

http://iosrjournals.org/iosr-jestft/papers/vol9-issue4/Version-1/G09415158.pdf

http://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0102915

https://www.researchgate.net/profile/David_Ezra/publication/222910446_An_endophytic_Gliocladium_sp._of_Eucryphia_cordifolia_producing_selective_volatile_antimicrobial_compounds._Plant_Sci/links/5490268a0cf225bf66a81d58.pdf

https://www.researchgate.net/publication/225486637_A_Petri_Plate_Technique_for_Testing_Pathogenicity_of_Fungi_to_Seedlings_and_Inducing_Fungal_Sporulation

https://www.researchgate.net/profile/Dashavantha_Vudem/publication/222563616_Production_of_transgenic_plants_resistant_to_leaf_blast_disease_in_finger_millet_Eleusine_coracana_L_Gaertn/links/53cf6d5e0cf2f7e53cf7f5ec.pdf

http://link.springer.com/article/10.1007/BF00327835

http://www.apsnet.org/publications/plantdisease/backissues/Documents/1989Articles/PlantDisease73n06_459.PDF

https://www.researchgate.net/profile/David_Dowling/publication/13680074_Impact_on_arbuscular_mycorrhiza_formation_of_pseudomonas_strains_used_as_inoculants_for_biocontrol_of_soil-borne_fungal_plant_pathogens/links/004635215e1338160f000000.pdf

https://www.researchgate.net/profile/David_Dowling/publication/13680074_Impact_on_arbuscular_mycorrhiza_formation_of_pseudomonas_strains_used_as_inoculants_for_biocontrol_of_soil-borne_fungal_plant_pathogens/links/004635215e1338160f000000.pdf

https://www.apsnet.org/publications/phytopathology/backissues/Documents/1987Articles/Phyto77n10_1475.PDF

Hoping this will be helpful            

Regards

Prof. Houda Kawas

Article An endophytic Gliocladium sp. of Eucryphia cordifolia produc...

Article A Petri Plate Technique for Testing Pathogenicity of Fungi t...

Article Production of transgenic plants resistant to leaf blast dise...

Article Impact on Arbuscular Mycorrhiza Formation ofPseudomonas Stra...

By Pathogenicity test, or by pigmentation or by producing spores or by produce odor

Dear Mr. Oady Matny : Thank you for your opinion. I will focus on what have you suggested.

Dear Prof Houda Kawas : Million of thank you for you Sir. It really helps me a lot in searching the best answer on what I should focus and look into. Thank you once again and may God rewards you the best.....

Dear Mr. Laith Al-Ani : I'm assessing pathogenicity test by mycelium production..I guess I can search what I'm looking for through all the articles given by Prof Houda Kawas....

Thank you sooooooo muchhhhhhh Gentlemen......

Dear Maizan Ismail

You most welcome

Houda

If I am not confused with your question, I could suggest you to go for Ethyl acetate extraction method followed by agar well diffusion technique for the bioassay.