Comparison of sampling methodologies for site‐specific management ofAvena sterilis

Abstract

The ability to manage weed infestations in a spatially precise manner requires efficient and accurate methods of mapping weed distributions. A study was conducted to compare four different ground-based methods for collecting georeferenced information on infestations of Avena sterilis in winter wheat and barley. Sampling was performed at harvest by scoring panicle density, either from the ground or from a combine, by counting the number of panicle contacts with a stick moved horizontally over the crop canopy by an observer walking through the field, and by sampling A. sterilis seed rain on the ground. No significant differences were observed among the populations estimated by the four methods. A partial budget analysis of the in-season costs and benefits of spraying patches using these methods showed that visual scoring from the combine was the most appropriate method for the creation of weed management maps to be used for patch spraying in the following season. As a large variety of spatial patterns may be found in fields, the recommended sampling method might be fieldspecific and optimality should be verified for general use. Keywords: sampling methods, weed management, patch spraying, herbicide savings, herbicide dose. BARROSO J, RUIZ D, FERNANDEZ-QUINTANILLA C, LEGUIZAMON ES, HERNAIZ P, RIBEIRO A, DIAZ B, MAXWELL BD & REW LJ (2005) Comparison of sampling methodologies for site-specific management of Avena sterilis. Weed Research 45, 165-174.

Assessing the opportunity for site‐specific management of Avena sterilis in winter barley fields in Spain

“…Herbicide application maps were based on the prescription rules showed in Table 1. Limit values for A. sterilis infestation in site‐specific treatments were conservative, that some areas, especially buffer areas, would receive higher rates than those suggested by Barroso et al. (2005).…”

“…Because of the relatively large year‐to‐year variation in yield loss responses (Torner et al. , 1991; Barroso et al. , 2005) and because of the fact that we were trying to define strategic approaches to weed control, a broad description of yield loss risks was considered more convenient than very specific descriptions.…”

“…Herbicide treatments in the two site‐specific strategies were assigned based on the infestation levels present at harvest in the previous season. Visual scoring from a combine harvester has been shown to be appropriate for the creation of A. sterilis management maps to be used for patch spraying in the following seasons (Barroso et al. , 2005).…”

Spatial stability of Avena sterilis ssp. ludoviciana populations under annual applications of low rates of imazamethabenz

“…, 1992). Avena ludoviciana mapping studies conducted in winter cereal fields in central Spain have shown an aggregated pattern of this species in the absence of herbicide treatments (Barroso et al. , 2001; Ruiz et al.…”

“…It is well established that weeds are generally aggregated in patches within a field (Marshall, 1988;Wiles et al, 1992). Avena ludoviciana mapping studies conducted in winter cereal fields in central Spain have shown an aggregated pattern of this species in the absence of herbicide treatments (Barroso et al, 2001;Ruiz et al, 2002). This fact is important from the point of view of weed management.…”