Submitted to: International Conference on Precision Agriculture Abstracts & Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 3/2/2002
Publication Date: 7/14/2002
Citation: RIEDELL, W.E., LANGHAM, M.A., OSBORNE, S.L., HESLER, L.S. REMOTE SENSING OF BARLEY YELLOW DWARF AND WHEAT STREAK MOSAIC DISEASE IN WINTER WHEAT CANOPIES. INTERNATIONAL CONFERENCE ON PRECISION AGRICULTURE ABSTRACTS & PROCEEDINGS. 2002.
Technical Abstract: A 3-yr field experiment was conducted at Brookings SD during the 1998- 1999, 1999-2000, and 2000-2001 growing seasons. Wire mesh cages (1-m long x 1-m wide x 0.5-m tall) were placed in the field when the fall- planted winter wheat ('Crimson') reached the second leaf stage. BYDV (barley yellow dwarf virus) treatments were established by distributing viruliferous bird cherry-oat aphids evenly across all plants contained in the cage. WSMV treatments were applied with a controlled infection technique using a high-pressure spray that contained WSMV and silica carbide powder (600 mesh). Control plants received no virus infections. Canopy reflectance (350 to 1100 nm) was measured at the flag leaf development stage. Reflectance spectra, relative to a 25 % reference panel standard, were calculated by dividing canopy radiance by reference radiance at each wavelength. Reflectance sensitivity (which identifies specific wavelengths where disease treatments affected leaf reflectance) was computed by dividing the reflectance difference (obtained by subtracting the canopy reflectance of control plants from that of virus-treated plants) by the control reflectance at each wavelength. Grain yield and yield components were measured at crop maturity. Reflectance spectra from control plant canopies over the 3 years of the experiment showed chlorophyll absorption bands in the 420 to 460 nm and 610 to 630 nm regions, chlorophyll reflectance/transmittance in the 480 to 510 nm region, red-near infrared transition in the 630 to 690 nm region with the near infrared plateau starting at about 690 nm. For BYDV treatments in 1999 and 2001, reflectance spectra had lower reflectance