Redroot pigweed (Amaranthus retroflexus L.) is a nuisance weed that affects\ncotton (Gossypium hirsutum L.) growth and yield worldwide. Being able to\ndistinguish redroot pigweed from cotton would help producers and crop\nconsultants better implement strategies used to suppress and control it.\nHyperspectral reflectance properties of weed and crop canopies have been\nused to differentiate between them. Currently, no information is available on\nthe application of hyperspectral data to distinguish redroot pigweed from\ncotton with different leaf shapes. Positive results will further support the exploration\nof remote sensing technology for distinguishing redroot pigweed\nfrom cotton. The objectives were to compare canopy hyperspectral reflectance\nof redroot pigweed to canopy hyperspectral reflectance of okra and super\nokra leaf cotton and to identify regions of the spectrum in which differences\nexist in their reflectance properties. Hyperspectral reflectance measurements\nof redroot pigweed and cotton were obtained with a spectroradimeter\non May 6 and June 27, 2019. Plants grown in a greenhouse were used\nfor this study. One-hundred and sixty-two 10-nm bands (400 - 2350 nm\nspectral range) were evaluated with analysis of variance (p less than equal to 0.05) and Dunnettâ??s\ntest (p less than equal to 0.05) to determine the wavebands that were useful for separating\nredroot pigweed from okra leaf and super okra leaf cotton. The following\nbands were consistent in distinguishing redroot pigweed and okra leaf\ncotton on both dates: 420 nm, 510 - 650 nm, 690 - 740 nm, and 2000 - 2010\nnm; whereas, 400 - 500 nm, 1480 - 1780 nm, and 1990 - 2350 nm were identified\nfor both dates for separating redroot pigweed from super okra leaf cotton.\nCommercial imaging systems used on ground-based or airborne platforms\ncan be easily tuned into the spectral bands listed in this study, thus\nproviding managers with a tool to use for identifying redroot pigweed in cotton\nproduction systems.
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