irksome vs pestiferous

irksome

adj
  • Marked by irritation or annoyance; disagreeable; troublesome by reason of long continuance or repetition 

pestiferous

adj
  • annoying, vexatious 

  • containing organisms that cause contagious diseases 

How often have the words irksome and pestiferous occurred in a corpus of books? (source: Google Ngram Viewer )