Separate biological causes from environmental, material and handling causes. Several can coexist. For example, cap damage can follow handling, persistent wetness or a crop-health problem; appearance alone may not separate them. Ask what observation would make each explanation less likely. Healthy beds using the same compost may be informative, but they do not automatically clear that compost if the handling and environment differed.
For each possible cause, list a check, the result and what remains unresolved. Do not replace an unknown with a precise-looking confidence percentage. Send the record to the specialist with a specific question: what further evidence is needed, what can be done immediately, and what would confirm the identification? This produces a better consultation than asking for a medicine against a photograph.