Step 1: Understanding poultry diseases.
Poultry birds can suffer from diseases caused by fungi, bacteria, viruses, and parasites. Identifying the causative agent helps in classification of diseases.
Step 2: Nature of fungal diseases.
Aspergillosis, thrush, and favus are fungal diseases caused by different fungal species affecting respiratory tract or skin of poultry birds.
Step 3: Explanation of Pullorum.
Pullorum disease is caused by the bacterium {Salmonella pullorum}. It is a bacterial disease and not a fungal infection.
Step 4: Analysis of options.
(A) Aspergillosis: Fungal disease caused by {Aspergillus}.
(B) Pullorum: Bacterial disease, hence not fungal.
(C) Thrush: Fungal infection caused by {Candida}.
(D) Favus: Fungal skin disease.
Step 5: Conclusion.
Pullorum is not a fungal disease of poultry and is the correct answer.