chalkbrood
noun
chalk·brood ˈchȯk-ˌbrüd 
: a disease of honeybees that is fatal to developing larvae and is caused by a fungus (Ascophaera apis)
Note: Larva affected with chalkbrood become covered by a white, woolly growth and then harden to a chalky white to grayish-black mass.
Word History
First Known Use
1974, in the meaning defined above