Scots Pine, D. Zimmermani Control, Illinois, 1977-78

A 5-acre nursery of Scots pine trees of 4-6 ft in height planted 4 feet apart and consisting of 14 rows with ca 100 trees per row was selected in Whiteside County, Illinois because of the high incidence of Zimmerman pine moth damage. On September 10, 1976, 9 trees that had symptoms of Zimmerman pine moth infestations were tagged in each of 14 rows. During May 1977 and 1978 the hardened sap exudate from previous infestations was scraped off all tagged trees. Each insecticide treatment was applied onto the same 18 trees (9 trees in each of 2 adjoining rows) for 2 consecutive years. Fall treatments: On September 14, 1976 and September 4, 1977 insecticide sprays were applied until runoff onto the branches and trunks of the trees using a 100 gallon hydraulic sprayer. Spring treatments: On April 17, 1977 and April 27, 1978 other trees in adjoining rows were treated as described in the fall applications, using the same insecticides.