Determination of differences in crop injury from aerial application of glyphosate using vegetation indices

• Published in: Computers and electronics in agriculture Vol. 77; no. 2; pp. 204 - 213
• Main Authors: Ortiz, B.V., Thomson, S.J., Huang, Y., Reddy, K.N., Ding, W.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-07-2011; Elsevier
• Subjects: Aerials; Agronomy. Soil science and plant productions; Biological and medical sciences; Canonical correlation analysis; Chlorophylls; Correlation analysis; Crops; Fundamental and applied biological sciences. Psychology; Glyphosate; Injuries; Injury analysis; Parasitic plants. Weeds; Phytopathology. Animal pests. Plant and forest protection; Remote sensing; Semivariogram; Vegetation; Vegetation Indices; Weeds; Vegetation Indices; Semivariogram; Glyphosate; Canonical correlation analysis; Remote sensing; Vegetation index; Pesticides; Organic phosphonate; Systemic; Herbicide; Canonical correlation; Correlation analysis; Damage; Aerial application
• ISSN: 0168-1699; 1872-7107
• DOI: 10.1016/j.compag.2011.05.004

► The level of crop injury from glyphosate aerial drift was assessed using multispectral vegetation indices. ► Seven vegetation indices were evaluated for glyphosate injury identification using a canonical correlation analysis. ► The Chlorophyll Vegetation Index (CVI) best correlated with field-measured plant injury data. ► Levels of crop injury were assessed by observing residual values calculated from the CVI images.
Crop injury caused by off-target drift of herbicide can seriously reduce growth and yield and is of great concern to farmers and aerial applicators. Farmers can benefit from identifying an indirect method for assessing the level of crop injury. This study evaluates the combined use of statistical methods and vegetation indices (VIs) derived from multispectral images to assess the level of crop injury. An experiment was conducted in 2009 to determine glyphosate injury differences among the cotton, corn, and soybean crops. The crops were planted in eight rows spaced 102
cm apart and 80
m long with four replications. Seven VIs were calculated from multispectral images collected at 7 and 21
days after the glyphosate application (DAA). At each image collection date, visual injury estimates were assessed and data were collected for plant height, chlorophyll content, and shoot dry weight. From the seven VIs evaluated as surrogate for glyphosate injury identification using a canonical correlation analysis (CCA), the Chlorophyll Vegetation Index (CVI) showed the highest correlation with field-measured plant injury data. CVI image values were subtracted from the CVI average values of the non-injured area to generate CVI residual images (CVI
res
). Frequency distribution histograms of CVI
res
image values were calculated to assess the level of injury between crops. These data suggested that injury increased from 7DAA to 21DAA with corn exhibiting higher severity of injury than cotton or soybean, while only moderate injury was observed for cotton. The techniques evaluated in this study are promising for estimating the level of glyphosate herbicide drift, which can be used to make appropriate management decisions considering crop proximity.