This paper was presented at the Art, Science and Applications of Reflectance Spectroscopy Symposium sponsored by ASD Inc. and IEEE GRSS, February 23-25, 2010 in Boulder, Colorado.

Authors: KeRu Wang¹, ShaoKun Li², Bing Chen¹
Affiliations:
(1) Key Laboratory of Oasis Ecology Agriculture of Xinjiang Corps/Shihezi University, Shihezi ,Xinjiang, China
(2) Institute of Crop Science, Chinese Academy of Agricultural Sciences/The National Key Facilities for Crop Genetic Resources and Improvement, NFCRI, Beijing, China

Abstract

Verticillium wilt and aphids are the major stressors affecting cotton production in Xingjiang, and are becoming increasingly serious. To monitor the disease and insects in cotton quickly and accurately is important for the scientific and effective prevention or reduction of the disease and insect damage to cotton and for protection of the environment. The objective of this paper is to compare characteristics of the spectra of cotton leaves infected with verticillium wilt and aphids, and to offer a theoretical foundation for monitoring cotton disease and insects using remote sensing. The spectral reflectance of single cotton leaves infected with verticillium wilt and aphids was measured in the nursery and in the field during different growth phases. In leaves infected with verticillium, spectral reflectance increased significantly in the visible region (400-700nm) and near-infrared region (700-1300nm) with the increase in disease level. Especially significant was the525-680nm region when disease reached level 2, and this is when it can be best diagnosed with remote sensing. The regions 434-724 nm and 909-1600nm were shown to be band regions sensitive to disease in a single leaf. Cotton infected with aphids was spectrally different from the verticillium infected leaves. The 434-727 nm region is best for distinguishing cotton leaves infected by aphids, and 648 nm can be used as the best single band to detect aphid-infected cotton leaves. Furthermore, analysis of the physiology of leaves infected by verticillium wilt and by aphids show that chlorophyll a, b and chlorophyll a+b in the cotton leaves infected by verticillium wilt decreased and the carotenoid content slightly increased.