negative regulation of ascus development
Any process that stops, prevents, or reduces the frequency, rate or extent of ascus development, a saclike structure produced by fungi of the phylum Ascomycota (sac fungi) in which sexually produced spores (ascospores), usually four or eight in number, are formed.
GO:0075262
negative regulation of spore-bearing organ development
is_a
GO:0075318
regulation of ascus development
is_a
GO:0075317
ascus development
negatively_regulates