Field trials were conducted to compare on-site visual evaluations with color-infrared photography (CIR), and near-infrared (NIR) videography (video) and hand-held radiometry (HHR) for detecting and mapping dicamba injury in cotton. CIR, video, and HHR detected 48%, 42% and 36%, respectively, of the injured crop area as defined by visual evaluation (injury ratings >0 on a scale of 0 to 9). The remote techniques were unable to differentiate crop injury that did not involve the entire plant canopy. Reflectance measurements in the visible red (R) (630–690 nm) and NIR (760–900 nm) wavelengths were taken and used in herbicide dosage prediction equations. Predicted herbicide dosages were significantly, positively correlated (P≤0.01) with physical measures of herbicide present. These studies suggest that remote detection and mapping of moderate and severe herbicide injury is possible. Further, NIR videography, with near-real-time capability and low cost may be the system of choice for this type of application.

Greenhouse studies were conducted to determine yellow nutsedge response to selective placement of a 5-cm layer of norflurazon-treated soil above, below, or above plus below pregerminated nutsedge tubers. Norflurazon at 1.68 kg ai/ha applied postemergence (POST) as a foliar, soil, or foliar plus soil treatment was also evaluated. Soil concentrations of norflurazon at 1.5 mg/kg (w/w) applied below or above plus below nutsedge tubers reduced yellow nutsedge shoot numbers at least 69%, shoot height at least 71%, shoot dry weights at least 77%, and root tuber dry weights at least 89%. Yellow nutsedge growth reduction with norflurazon was greatest when norflurazon was placed in the soil profile below or above plus below the yellow nutsedge tubers. Placement of norflurazon above yellow nutsedge tubers did not reduce shoot number, height, or dry weight until the foliar portion of plants were removed 39 d after treatment. POST application of norflurazon did not reduce initial yellow nutsedge shoot number regardless of application method. Foliar-only POST application of norflurazon was less effective for reducing numbers of emerged yellow nutsedge than application to soil only or soil plus foliage.