Location: Crop Production Systems ResearchTitle: Airborne remote sensing assessment of the damage to cotton caused by spray drift from aerially applied glyphosate through spray deposition measurements Author
|Bright, Jerry - Roger|
Submitted to: Journal of Biosystems Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/27/2010
Publication Date: 11/1/2010
Citation: Huang, Y., Thomson, S.J., 0rtiz, B.V., Reddy, K.N., Ding, W., Zablotowicz, R.M., Bright Jr, J.R. 2010. Airborne remote sensing assessment of the damage to cotton caused by spray drift from aerially applied glyphosate through spray deposition measurements. Journal of Biosystems Engineering. 107:212-220. Interpretive Summary: Off-target drift of aerially applied herbicide can cause unexpected crop injury. This is of great concern to farmers and aerial applicators. To determine the extent of crop injury due to near-field drift of herbicide, an experiment was conducted through a single aerial application of glyphosate (a broad-spectrum systemic herbicide), over a field planted in replicated blocks of cotton. Spray samplers were placed in the spray swath and in several downwind positions to quantify relative concentration of applied chemical. An Air Tractor 402B agricultural airplane equipped with fifty-four spray nozzles was flown down the center of the field to apply Roundup Weathermax and tracer (Rubidium Chloride) for spray measurement. One, two and three weeks after the experiment aerial Color-Infrared (CIR) imagery were acquired over the crop field using a Global Positioning System (GPS)-triggered Geospatial Systems MS-4100 camera system on the Air Tractor airplane to assessed glyphosate spray drift injury to cotton. The imagery data and agreed with relative spray deposition in predicting cotton damage from glyphosate drift and may be used as a tool to assess crop injury due to drift.
Technical Abstract: Off-target drift of aerially applied glyphosate can cause plant injury, which is of great concern to farmers and aerial applicators. To determine the extent of crop injury due to near-field drift, an experiment was conducted with a single aerial application of glyphosate. For identification of the drift effect on cotton plant, a field was planted in replicated blocks of cotton. Spray samplers were placed in the spray swath and in several downwind orientations to quantify relative concentration of applied chemical. An Air Tractor 402B spray airplane equipped with fifty-four CP-09 nozzles was flown down the center of the field to apply 22 oz/acre of Roundup Weathermax and Rubidium Chloride tracer at a 5 gal/acre spray rate. Relative concentrations of this tracer were quantified at downwind spray samplers. At one week intervals aerial color-infrared imagery was obtained over the field using a Global Positioning System-triggered multispectral MS-4100 camera system. This study’s main focus was to assess glyphosate spray drift injury to cotton using spray drift sampling and the color-infrared imagery. The processed drift and image data were highly correlated (coefficients from -0.38 to -0.97 in 1, 2, and 3 weeks after treatment). The drift and image data were used as the indicators of percent visual injury in regressions with a strong ability of variability explanation (R2 from 0.36 to 0.90 for drift data; from 0.20 to 0.90 for image data in 1, 2, and 3 weeks after treatment). The results indicate that spray drift sampling and airborne remote sensing can be useful for determining cotton injury caused by the drift of aerial applied glyphosate. The results are also helpful for determining the extent of near-field drift sampling, and demonstrated that airborne multispectral imaging can be viable tools for determining the extent of damage relative to derived concentrations of glyphosate.