Table 3.

The reported use of sprays by commercial arborists in 1982 to control insects or diseases, and the ranking of relative importance within each.

Use frequency (no. arborists)Relative importancea
  Canker or dieback7213
  Leaf spots19254
  Powdery mildew14224
  Elm bark beetles24123
  Leaf beetles26012
  Moths (gypsy or tussock)16100
  Plant bugs19000
  Scale insects231086
  • a The number of arborists who rated this disease (or insect pest) as first, second, or third in importance in his area.