Hawthorn Insect Control, Trial One, Ft. Collins, Colorado, 1995

Abstract

Abstract Plots were established at the WD. Holley Plant Environmental Research Center located on the campus of Colorado State University. Two trees, approximately 8-20 ft (4 inch dbh) and established at the site for approximately 10 years were utilized in the experiment. Individual branches were sprayed with different compounds to run-off. Each branch was treated as a single experimental unit, with a complete replication being a group of branches with similar orientation on the tree. Plot design was a RCB with 5 replications. Treatments were applied on 5 May by spraying terminal branch segments with a pump-mister sprayer to the point of run-off. Although weather was clear at the time of application, soil moisture was high at the site due to prior rainfall and VS inch of rain fell at the site within 24 h of application. Treatments were evaluated on 7 Jun by counting the number of mealybugs present on 19.5 inches of terminal branch segment. Aphid ratings were taken on the same date by assessing the damage and curling caused by an infestation of a woolly aphid. An eleven point rating system was used to rate leaf curling damage by the aphids per 19.5 inches of terminal branch segment. The rating scale was as follows: 0 = No leaves curled, 1 = 1-5 leaves with light curling, 2 = 6-10 leaves with light curling, 3 = 10+ leaves with light curling, 4 = 1-5 leaves with moderate curling, 5 = 1-5 leaves with moderate curling, 6 = 6-10 leaves with moderate curling, 7 = 10+ leaves with moderate curling, 8 = 1-5 leaves with severe curling, 9 = 6-10 leaves with severe curling, 10 = 10+ leaves with severe curling.