Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/2/2003
Publication Date: 9/1/2003
Citation: Sudbrink, D.L., Harris, F.A., Robbins, J.T., English, P.J., Willers, J.L. 2003. Evaluation of remote sensing to identify variability in cotton plant growth and correlation with larval densities of beet armyworm and cabbage looper (Lepidoptera: Noctuidae). Florida Entomologist. 86:290-294. Interpretive Summary: Beet armyworm is an occasional pest in the Midsouth that can become severe under some environmental conditions. Infestations of beet armyworm in cotton are associated with canopy development and varying levels of plant nutrients such as low levels of potassium and high levels of zinc. Cabbage looper is another occasional pest only reaching damaging levels late-season. High plant densities and vigorously growing plants are typically attractive for this pest. Remote sensing is a promising technology that may provide early detection of localized infestations of many cotton pests, because it can provide information about plant vigor and canopy structure. Therefore, the objective of this study was to evaluate remote sensing technology to identify factors in cotton growth and development related to infestations of these two cotton pests.
Technical Abstract: Field experiments were conducted from 2000 to 2002 in the Mississippi Delta to evaluate remote sensing technologies for identifying factors in cotton growth and development related to infestations of beet armyworm and cabbage looper. Larval defoliation of plants was monitored using remote sensing techniques including aerial and hand-held sensors as well as visual measurements of damage. Percent reflectance differed for beet armyworm infested leaves compared to uninfested leaves. In two whole field studies, more beet armyworm hits were found in zones of less vigorous and open canopy, which corresponded to lower normalized difference vegetation index (NDVI) values calculated from remotely sensed imagery. Percent light penetration of canopy was greater for plots damaged by looper larvae than for less damaged plots where looper larvae were controlled with insecticide, but NDVI values were not different.