Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 21, 2010
Publication Date: August 27, 2010
Citation: Martin, D.E., Lopez, J., Lan, Y., Fritz, B.K., Hoffmann, W.C., Duke, S.E. 2010. Novaluron as an ovicide for bollworm on cotton: Deposition and efficacy of field-scale aerial applications. Journal of Cotton Science. 14:99-106. Interpretive Summary: The bollworm/tobacco budworm pest complex continues to plague cotton producers especially on non-Bt cotton grown to meet Bt refugia requirements or in areas where non-Bt cotton predominates. In these cases, insecticidal control remains an important crop protection component especially in cotton-growing areas where insecticides are used to control these pests on other crops. Appropriate insecticide selection and optimum application are important for efficient use of insecticides in these cases. Novaluron, an insecticide that is compatible with integrated pest management (IPM), was found to effectively prevent larval hatch from bollworm eggs when applied by aerial application technologies that improved spray coverage. This information will help producers enhance IPM programs for sustainable cotton production.
Technical Abstract: Novaluron, Diamond 0.83 EC, was evaluated for deposition on cotton and ovicidal efficacy against bollworm, Helicoverpa zea (Boddie), because of the need to use insecticides with modes of action different than synthetic pyrethroids. Novaluron at the lowest label recommended rate was aerially-applied with rotary atomizers and CP nozzles at spray rates of 19 l/ha (2 gpa) including addition of Aero Dyne-Amic adjuvant for one CP nozzle treatment, and CP nozzles at 47 l/ha (5 gpa). These treatments were compared to methomyl, Lannate LV, applied with CP nozzles at 19 l/ha (2 gpa) and an untreated check. Application equipment was setup to provide a Dv0.5 of 175 microns. Ovicidal efficacy was determined by collecting eggs from treatments at 0, 1, and 5 days after treatment (DAT). Test results showed greater deposition from the 47 l/ha application versus the 19 l/ha application and significantly greater deposition with the use of the adjuvant Aero Dyne-Amic. Total mortality (%) which included dead eggs (fertile, no larval hatch) and dead larvae (hatched, no feeding) was significantly higher than the untreated check (32.4%) on 0 DAT for 4 treatments: novaluron applied with rotary atomizers (74.7) and CP nozzles (69.1, 72.2) at 19(2) and 47(5) l/ha (gpa), respectively, and methomyl (78.4). At 1 DAT, total mortalities were: 69.2 % (novaluron/rotary atomizers) and 68.1 % (CP nozzles at 47 l/ha), and although differences were not statistically significant, the efficacy trend was the same except for a decrease with methomyl. These data show that novaluron is an effective ovicide for bollworm on cotton especially if aerially-applied with rotary atomizers at 19 l/ha or CP nozzles at 47 l/ha.