Step 1: Understanding the Concept:
A sporodochium is an asexual fruiting body characterized by a cushion-like stroma covered with a dense layer of short, simple conidiophores.
It is a taxonomic feature used to classify deuteromycetes (fungi imperfecti).
Step 2: Detailed Explanation:
Let us look at the asexual structures of the listed genera:
1. Graphium: Graphium is characterized by the production of synnemata, which are erect, cement-like bundles of conidiophores.
2. Phoma: Phoma is a member of the Sphaeropsidales and produces pycnidia, which are globose, flask-shaped, ostiolate fruiting bodies enclosing conidia.
3. Fusarium: Fusarium species produce macroconidia and microconidia.
The macroconidia are typically produced on specialized, cushion-like conidiophorous masses called sporodochia. Under humid conditions, these sporodochia appear as bright orange, pink, or peach-colored masses on infected plant tissues.
Step 3: Final Answer:
Fusarium is the plant pathogen known for producing sporodochia. Therefore, the correct option is (D).