(G30) FRASER FIR: Abies fraseri (Pursh) Poi. MULTIPLE APPLICATION MANAGEMENT STUDY TO SUPPRESS ELONGATE HEMLOCK SCALE WITH ACEPHATE AND DIMETHOATE ON FRASER FIR CHRISTMAS TREES, 2003 P.R. Heller Department of Entomology Pennsylvania State University University Park, PA 16802 Phone: (814) 865-3008 Fax: (814) 865-3048 E-mail: firstname.lastname@example.org D. Kline E-mail: email@example.com Elongate hemlock scale (EHS): Fiorinia externa (Ferris) This experiment was conducted on 6 to 8 ft EHS infested Fraser fir Christmas trees located in Columbia Co. to determine the efficacy of conventional formulations. A RCB design was used and replicated four times. Treatments were applied at the rate of 100 gpa (315 ml/tree, 120 trees/acre) by using a Solo 432 backpack sprayer. At treatment time one (28 May), the following environmental conditions existed: air temp, 60°F; water pH, 7.0; percent relative humidity, 82; application time, mid morning; and skies were partly sunny. At treatment time two (24 Jun), the following environmental conditions existed: air temp, 83°F; water pH, 7.0; percent relative humidity, 56; application time, mid day; and skies were sunny. At treatment time three (22 Jul), the following environmental conditions existed: air temp, 66°F; water pH, 7.0; percent relative humidity, 94; application time, mid morning; and skies were cloudy. Samples were removed from lower third of the crown of each tree on 6 Aug to determine percent dead scales calculated as the no. EHS living + no. EHS dead = total scales recorded; no. dead/total no. scales × 100 = % dead EHS. A minimum of one twig from the 2003 new lateral growth was removed from each tree at each of four cardinal (North, South, East, West) directions. Twigs were then individually placed in plastic bags, marked, and transported back to the laboratory via ice coolers. Fifty needles were randomly removed from each twig at four cardinal directions. A total of 200 needles were examined from each tree. The total no. of EHS life stages present were counted and examined under a stereo dissecting microscope. EHS life stages located on 2003 needles were recorded as either dead or alive. Data was analyzed by using ANOVA and means were separated with WD (P ≤ 0.05). Dimethoate 267 applied twice (i.e., at crawler hatch and ca. four weeks later) provided an average of 86.5% EHS death, while Dimethoate 267 applied three times (i.e., at crawler hatch, plus, ca. four and eight weeks later) provided an average of 94.9% EHS death. Both treatments were highly significant from untreated check one and two. Orthene 75 TTO applied twice (i.e., at crawler hatch and ca. four weeks later) provided an average of 50.3% EHS death, while Orthene TTO Spray 97 applied three times (i.e., at crawler hatch, plus, four and eight weeks later) provided an average of 66.0% EHS death. Dimethoate 267 treatments, two and three applications, were significantly different from the Orthene TTO Spray 97’s multiple treatments. A single application of either Dimethoate 267 or Orthene TTO Spray 97 failed to control EHS when compared to both untreated checks. Three applications of Dimethoate 267 provided the most significant control of EHS. However, it is important to remember that no treatment provided total eradication of EHS which makes this a challenging armored scale to manage. No phytotoxicity was noted. Avg no. EHS life stages/200 needles Treatment/ Rate formulation amt product/gallon No. living No. dead % dead Untreated check one --- 97.3ab 0.0c 0.0e Untreated check two --- 96.8ab 0.0c 0.0e Dimethoate 267 22.5 ml 84.3bc 3.3b 9.7d Dimethoate 267 22.5 ml 3.0d 25.8a 86.5b Dimethoate 267 22.5 ml 3.0d 40.3a 94.9a Orthene TTO Spray 97 2.268 g 325.3a 2.8bc 0.3e Orthene TTO Spray 97 2.268 g 61.8bc 53.5a 50.3c Orthene TTO Spray 97 2.268 g 29.0c 54.0a 66.0c Means in a column followed by the same letter do not significantly differ (P > 0.05, WD). Data were transformed using an arc sine square root percent transformation; non-transformed data presented. No. EHS living + no. EHS dead = total scales recorded; no. dead/total no. scales × 100 = % dead EHS life stages. Application completed on 28 May 2003 (i.e., total of one treatment per tree replicate; 315 ml/tree). Applications completed on 28 May and 24 Jun 2003 (i.e., total of two treatments per tree replicate). Application completed on 28 May, 24 Jun, and 22 Jul 2003 (i.e., total of three treatments per tree replicate).
Arthropod Management Tests – Oxford University Press
Published: Jan 1, 2005