Effectiveness of A Soil-Injected Systemic Insecticide for Controlling Sucking Insects on Red Pine, 1978

Experiments to evaluate the effectiveness of the systemic insecticide, Cygon 400, applied by soil injection for controlling two bark-dwelling, sucking insects of red pine were conducted at the New Haven Country Club in Hamden, Connecticut. In July, 24 ornamental red pines of a similar height (7-8 m) and DBH (23-28 cm) were examined and found to be heavily infested with Matsucoccusresinosae and Pineusstrobi. On Aug2, two branches were sampled from the lower crown of each tree and the number of scales and aphids occurring beneath 100 bark flakes on the preferred 3-year-old growth and the number dead per 100 individuals were determined for each branch by microscopic examination. On Aug4, during peak abundance of summer generation cysts (second instar nymphs) of M. resinosae and immature hiemcprogrediens of P. strobi, 16 of the trees were randomly divided into 4 treatment groups and administered different doses of Cygon 400 mixed to a concentration of 0.5 lb ai ( I pt concentrate) per 100 gal water. Doses, chosen to approximate 0,1 2, and 3 gals per I inch DBH were 0, .05,. 10 and . 15 lb ai per tree. For the 4 trees in each treatment an equal volume of insecticide was delivered through an injection needle to a depth of .5 m at 10 positions encircling the tree at the drip line using a John Bean pump operating at a pressure of 200 psi. Trees were sampled 7,14, and 21 days following treatment and density and mortality of M. resinosae and P. strobi were determined as before. On Sepl3, following peak egg hatch of the fall generation of M. resinosae, 16 trees including 8 which had been given a 30 gal dose of Cygon 400 on Aug4 and 8 which had not been treated were sampled as before to determine density and mortality of recently settled first instar nymphs. On Sepl5, 4 of the previously treated trees and 4 of the untreated ones were anministered a 30 gal dose of Cygon 400 as before. Trees were sampled 21 days following treatment. Data were subjected to analyses of variance.