Novaluron as an ovicide: A model for evaluation of aerially-applied insectides. Part 2: Field Study

Authors: Martin, Daniel - Dan; Lopez, Juan De Dios; Hoffmann, Wesley; Fritz, Bradley - Brad

Submitted to: National Agricultural Aviation Association Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 12/7/2005
Publication Date: 12/7/2005
Citation: Martin, D.E., Lopez, J., Hoffmann, W.C., Fritz, B.K. 2005. Novaluron as an ovicide: A model for evaluation of aerially-applied insectides. Part 2: Field Study. National Agricultural Aviation Association Meeting. Paper No. AA05-005.

Interpretive Summary:

Technical Abstract: Comprehensive evaluation of efficacy of an aerially-applied insecticide to include optimization of equipment and spray parameters is visualized to consist of three phases: (1) laboratory studies to determine inherent toxicity and appropriate mortality assessment procedures; (2) spray table evaluations to determine optimum deposition characteristics for mortality; and (3) validation of spray table results under field conditions or evaluation of equipment not amenable to spray table evaluation. Novaluron, Diamond® 0.83 EC, was targeted for evaluation of ovicidal efficacy for control of bollworm, Helicoverpa zea (Boddie), on cotton because of the need to use insecticides in addition to synthetic pyrethroids for control of resistant bollworms infesting cotton after being treated on other crops with these insecticides. In this initial field test, novaluron at the lowest label recommended rate was applied with rotary atomizers and CP nozzles at spray rates of 19 l/ha (2 gpa) including addition of Dyne-Amic® adjuvant to 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. Treatments were replicated three times in a completely randomized block design in a Bt cotton field irrigated via central pivot located in the Brazos Valley River. Ovicidal efficacy was determined by collecting plant parts with eggs from treatments and placing them in plastic bags pre-treatment and 0, 1, and 5 days post-treatment. In the laboratory, individual eggs were cut out while attached to the plant part, placed in cups with artificial diet and checked for mortality either as eggs or larvae. Deposition data were based on analyses of 10 mylar plates and 10 water-sensitive papers placed on stands in a diagonal across each plot which was 2.1 ha in size. Deposition data were collected from all 3 replicates; however, efficacy data were collected from only 2 replicates post-treatment because one replicate was found to be conventional cotton serving as refugia and was sprayed with a synthetic pyrethroid shortly after test treatments were applied. 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. Mortality of eggs collected from the untreated check at 0, 1, 5 days post-treatment averaged between 20-25 percent. Egg mortalities statistically different from the check and equal were Lannate (72 and 69%) and Novaluron (67 and 65%) applied with CP nozzles at 19 l/ha (2 gpa) and 47 l/ha (5 gpa), respectively at 0 and 1 days after treatment (DAT). At 5 DAT, the only treatment egg mortality different from the check was Novaluron (42%) applied with rotary atomizers at 19 l/ha (2 gpa). Although this field evaluation was a first effort, results obtained on deposition and efficacy of Novaluron on cotton certainly encourage additional spray table and field evaluations to develop more specific guidelines for aerial application of this material as an ovicide for bollworm on cotton.