• Webb, F.E.
  Forestry Chronicle
  

The aerial spraying operations in New Brunswick against the spruce budworm have involved large areas in which tree mortality was imminent. In working out practical methods of timing applications, consideration has been given to protection of foliage as well as the immediate reduction of budworm populations. Modifications in operational techniques to lower spraying coasts and increase area coverage have necessitated earlier spraying and lighter dosages. Factors considered in the timing include the severity of infestation and defoliation, probable amount of spraying weather available, phenological differences between areas, the feeding habits of the budworm, and the tendency of spray to drift. The assessment of development was accomplished m,mainly by ground studies at representative locations and extended to the area at large by aerial surveys of balsam fir shoot growth. An analysis is made of spraying effectiveness in relation to timing habits of the budworm and extend to the area at large by aerial surveys of balsam fir shoot growth.

An analysis is made of spraying effectiveness in relation to timing from field data collected for studying the immediate results. From this, estimates are given of the average number of days during which various levels of rated effectiveness are attainable.