What are Kusala roots?
The 'three poisons', or three 'unwholesome roots' (akusala-mūla), are named as ignorance, attachment, and aversion &mdash; and the "wholesome roots" are their opposites:


  Opposite wholesome qualities
  
  The three wholesome mental factors that are identified as the opposites of the three poisons are:
  
  
  amoha (non-bewilderment); prajna (wisdom)
  alobha (non-attachment)
  adveṣa (non-aggression, lack of hatred); mettā (loving-kindness)
  
  
  The principal aim of the Buddhist path is to cultivate these and related positive qualities.


They're mentioned in for example, the Sammaditthi Sutta:


  
  "And what is the root of the wholesome? Non-greed is a root of the wholesome; non-hate is a root of the wholesome; non-delusion is a root of the wholesome. This is called the root of the wholesome.