Seems the "fatal flaw" with your design is the lack of a control to adequately compare/contrast the results.  Right now, you will probably compare / contrast the different concentrations/dilutions of the extract...but...you need the control.. a Tinea sample that is totally untreated...and since water is being used with the extract...you should also account for the possible affect of just water on another Tinea sample.So it seems you need to include an untreated Tinea sample AND a Tinea sample with 100% water along with the different concentrations you mentioned.Also...I am assuming you are using distilled water for the dilutions?  This would be another possible source of variation should you use tap water which contains other substances that could affect your results.I am curious about the time intervals you chose for the last part of your experiment...what is the rationale for them?6, 12, 24, 30, 48, 48 hrs.  I might suggest a time interval relative to the life cycle/development of the tinea fungus (or is that how you got the time intervals you listed?)..something like how long does it take to increase its area by 50% or some specified size or for some specific time interval.  this way you can see what concentrations have what degree of effect on the rate of tinea growth.Which also raises the question of how much tinea fungus is in each sample...(so I think you need to say something about how all the samples as standardized...size, type/amount of supporting growth medium, etc.)And wouldn't temperature be a factor?  Seems that most life forms have Goldilocks thermal characteristics (you know...too hot it dies...too cold it dies...just right and it survives and thrives).Hope this helps and doesn't give you too many headaches.....Best wishes on your project.