• Irving, H.J.
  

The hazard index is an estimate of the probability of tree mortality or irreversible damage. It is calculated by a formula that combines weighted estimates of egg abundance, defoliation and tree vigor. For 1979 it is estimated that moderate to severe hazard exists over 7 .B million on acres of the province's susceptible forests. 0f this, 2.6 million acres are in areas at least one mile from habitation and other sensitive areas; i.e. would qualify for spraying under 1979 limitations.