Potential for site specific management of Lolium rigidum (annual ryegrass) in Southern Australia.
type: CreativeWork
description: Weed spatial distribution is typically patchy and Lolium rigidum (annual ryegrass) distribution is no exception. The potential for site specific management of annual ryegrass was assessed to increase farmers’ financial returns through reduced herbicide costs while maintaining weed control in commercial paddocks near Bute and Tarlee, SA. Commercially available sensors N-Sensor, Greenseeker, Crop Circle and digital RGB camera were assessed for their ability to detect annual ryegrass patches in growing lentil, pea, canola and wheat crops at various growth stages. The best platform for annual ryegrass detection was the digital camera with an Excess Red – Excess Green algorithm applied to the image to delineate plant matter from background soil. The best relationship for this system was an R² of 0.85 and 0.86 in Ronnies and Stones North paddock respectively when the lentils and peas were at the 10-12 node stage and the annual ryegrass was at early-mid tillering. The N-Sensor was used to map annual ryegrass in lentil, pea and canola crops with R² values from 0.15 to 0.88. Poor correlations were related to misclassification due to the presence of other weed species or variability in crop growth. When these effects were accounted for, the correlations improved with R2 from 0.27 to 0.86. Four paddocks were monitored in three seasons between 2006 and 2009 to determine stability of annual ryegrass populations at fixed locations. Annual ryegrass populations were relatively stable with high density locations typically staying high between seasons and low density locations typically staying low. The relationships between seasons ranged from R² 0.53 to 0.94. Of the locations that changed ranking from being relatively low density to relatively high between seasons many could be explained by their proximity to the patch boundary. Herbicide efficacy dependence on population density was assessed by counting a wide range of annual ryegrass densities and recounting the surviving plants …
abstract: Weed spatial distribution is typically patchy and Lolium rigidum (annual ryegrass) distribution is no exception. The potential for site specific management of annual ryegrass was assessed to increase farmers’ financial returns through reduced herbicide costs while maintaining weed control in commercial paddocks near Bute and Tarlee, SA. Commercially available sensors N-Sensor, Greenseeker, Crop Circle and digital RGB camera were assessed for their ability to detect annual ryegrass patches in growing lentil, pea, canola and wheat crops at various growth stages. The best platform for annual ryegrass detection was the digital camera with an Excess Red – Excess Green algorithm applied to the image to delineate plant matter from background soil. The best relationship for this system was an R² of 0.85 and 0.86 in Ronnies and Stones North paddock respectively when the lentils and peas were at the 10-12 node stage and the annual ryegrass was at early-mid tillering. The N-Sensor was used to map annual ryegrass in lentil, pea and canola crops with R² values from 0.15 to 0.88. Poor correlations were related to misclassification due to the presence of other weed species or variability in crop growth. When these effects were accounted for, the correlations improved with R2 from 0.27 to 0.86. Four paddocks were monitored in three seasons between 2006 and 2009 to determine stability of annual ryegrass populations at fixed locations. Annual ryegrass populations were relatively stable with high density locations typically staying high between seasons and low density locations typically staying low. The relationships between seasons ranged from R² 0.53 to 0.94. Of the locations that changed ranking from being relatively low density to relatively high between seasons many could be explained by their proximity to the patch boundary. Herbicide efficacy dependence on population density was assessed by counting a wide range of annual ryegrass densities and recounting the surviving plants …
author: Trengove, Samuel Peter
keywords: annual ryegrass; precision agriculture; site specific weed management; herbicides; patches
date published: 2014
date modified: 2026-07-24T00:50:44Z
provider: University of Adelaide
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Adelaide

PropertyValue
property ID: Handle
value: http://hdl.handle.net/2440/91309