Tips and Techniques Pine Adelgid Control Revisited

摘要

The last installment of Tips and Techniques discussed the removal of pine adelgids with a brass brush. In spite of the clean removal this method accomplished, the adelgids returned with a vengeance. It is not clear whether the repopulation was from the source white pine that shades the bonsai garden or was from the adelgids hiding among the needles. Another bonsai friend suggested that high pressure water spray would be an effective solution to the problem without resorting to insecticide. When the adelgid population reached such proportions that something needed to be done. The water spray was tried. Figure 1 on the left shows the large accumulation of adelgids that had reappeared about 90 days after using the brush technique. A low volume, high velocity spray was generated by slightly opening the shutoff on the discharge end of the garden hose. It was amazing to watch the spray clear away the adelgids wherever it touched them directly. Not only was the trunk swept clean but the limbs, needles, and buds were cleaned as well. Since direct contact with the high velocity spray was necessary, the tree's various parts were sprayed from several angles to get complete coverage. The spray did no damage to the bark, needles, or buds. Figure 2 on the right shows the same section of trunk after spraying.