Spatial and temporal analysis of Convolvulus arvensis L. populations over four growing seasons

Abstract

Intensive field surveys of Convolvulus arvensis were conducted over the course of four growing seasons (1999)(2000)(2001)(2002) in a 1.6 ha section of a field located in Andalusia, southern Spain, cropped with wheat in 1999 and 2001 and with sunflower in 2000 and 2002. In order to characterise the spatial and temporal variability of C. arvensis density, geostatistical techniques were used. Data from the study were used to design precise herbicide spraying. The density and spatial distribution of C. arvensis varied widely with years and crops. In general, weed density was higher in wheat years (30.41 and 53.72, in 1999 and 2001, respectively) than in sunflower ones (20.67 and 24.03, in 2000 and 2002, respectively). C. arvensis density data showed strong and moderate spatial dependence. The C. arvensis density maps achieved by kriging were used to estimate the percentage of surface susceptible to be treated with a site-specific herbicide treatment based on an estimated economic threshold (ET) for each year of study. The C. arvensis infested areas varied considerably between years and crops. About 33 and 64% of the total infested area were moderately infested (density > 14 plant m −2 ) in wheat in 1999 and 2001, respectively, and about 17 and 19% in sunflower years (2000 and 2002, respectively). During the years cropped with sunflower the percentage of the total area infested with C. arvensis was reduced and therefore the area exceeding the economic threshold (AEET). So, if a given herbicide were applied just only to the areas exceeding the economic threshold, the average reduction in herbicide cost achieved in sunflower years could be around 81%. These approaches demonstrated the importance of growing different crops in weed management outcome, and could be useful to farmers and researchers in formulating a multiple-season weed management plan, especially since C. arvensis has been shown to have relatively stable patches over time and crop rotations in no-tillage systems.

Anthropogenic forcing on the spatial dynamics of an agricultural weed: the case of the common sunflower

“…The spatial correlogram (or related methods) is a common way to describe spatial patterns in plant ecology (Donald 1994; Legendre & Legendre 1998; Jurado‐Expósito et al . 2004).…”

Correlación Espacial Entre Malas Hierbas en Una Pradera Y Su Relación Con La Conductividad Eléctrica Aparente Del Suelo (Ce a )

“…Distintos autores han encontrado diferentes patrones espaciales de desarrollo vegetativo para las malas hierbas, no habiendo una constante que permita decir que característica del manejo de suelo es la que más incluye sobre su manifestación en el campo (Colbach et al, 2000;Jurado-Expósito et al, 2004, 2009. Shiratsuchi et al (2004) describen que el comportamiento de las especies de malas hierbas en campo no ocurre de manera uniforme, en este sentido Lass & Callihan (1993) y Colliver et al (1996) proponen que el muestreo de las malas hierbas en campo sea realizado junto con un mapeado del contorno de las zonas de mayor ocurrencia de las especies de malas hierbas, generando mapas de polígonos de infestación.…”

Spatial and temporal distribution of weeds in no-tillage system

“…Table 2. Parameters of the theoretical semivariograms and cross validation analysis referring to the modeling of spatial dependence of horseweed plants present in the studied area A study conducted by Jurado-Expósito et al (2004), in which geostatistical techniques and population maps obtained through kriging were used to estimate the cover percentage for local application, aiming at the control of Convolvulus arvensis L., allowed a reduction of 81% of the costs with herbicide. The mapping of weed populations promotes, besides the economic benefit, a reduction in the impacts caused by the application of agrochemicals on both the environment and the person who performs the application.…”