Fungicide acting on β-tubulin assembly is

Fungicide acting on β-tubulin assembly is Carbendazim.
Carbendazim, a systemic benzimidazole fungicide, is applied repeatedly to control plant diseases including soilborne diseases, over a growing season.
The mode of action of carbendazim involves interference in the biosynthesis of DNA during fungal cell division. carbendazim inhibits the assembly of microtubules in fungi while leaving plant microtubules unharmed.