Definition of "poysonous"

[…] but if you finde that their encrease and continuance multiply with your labour, it shall be then good for you to plant in diuers places of your Garden the hearbe called Palma Christi, in other places Garlicke and in other places Onyons, and it is an assured rule that no Moale will come néere where they grow for the strength and violence of their smell, is poysonous and deadly to those blinde vermines.

1614, Gervase Markham, chapter 7, in The Second Booke of the English Husbandman‎, London: John Browne, pages 45–46