Ferugo or Ferrugo: How To spell?
The word Ferugo is misspelled against Ferrugo, a noun meaning "A disease of plants caused by fungi, commonly called the rust, from its resemblance to iron rust in color."
Ferrugo has double "rr" is mispronounced as "r"Remember double 'RR' in between the strings fe & ugo which should not be misspelled with single 'R'
Wrong Spelling:  fe-r-ugo  Correct Spelling:  fe-rr-ugo 
Check more misspelled words of Ferrugo to spell it correct.