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

Abstract

Summary Long‐term experiments were conducted in two winter barley fields in central Spain to determine the spatial stability of Avena sterilis ssp. ludoviciana populations under annual applications of low rates of imazamethabenz herbicide. Weed density was sampled every year (over 5 years in the first field and over 3 years in the second) on the same grid locations prior to herbicide application. Although weed patches were stable in their location, weed density decreased in most of the years. In the first field, the populations decreased exponentially over the 5‐year period. The rates of population decline were dependent on the initial density of the population, being higher for the central core of the patches and lower for the low‐density areas. Under the conditions present in this experiment, it was possible to reduce heavy weed patches (up to 1200 seedlings m−2) down to relatively safe levels (18 seedlings m−2) in a period of 3 years using a density‐specific control programme, applying low rates of herbicides when weed densities were below a given level (1000 seedlings m−2). However, under adverse environmental conditions, half rates of the herbicide failed to control the weed populations adequately. The stability of the location of patches of A. sterilis ssp. ludoviciana suggest that weed seedling distributions mapped in one year are good predictors of future seedling distributions. However, the actual densities established each year will depend on the control level achieved the previous year and the climatic conditions present during the establishment period.

Spatial and temporal dynamics of Sorghum halepense patches in maize crops

“…The results obtained in this study have several important implications for SSWM of S. halepense. Previous studies have shown that the economic feasibility of using SSWM systems is conditioned by the frequency of re-mapping (Van Wychen et al, 2002;Barroso et al, 2004). Our results indicate that S. halepense patches are generally very compact and they expand slowly in a highly predictable way (in the same direction of field traffic).…”

“…Previous studies have shown that the economic feasibility of using SSWM systems is conditioned by the frequency of re‐mapping (Van Wychen et al. , 2002; Barroso et al. , 2004).…”

Are weed patches stable in location? Application of an explicitly two‐dimensional methodology

“…This straightforward and easy to understand method requires that the existence and spatial delineation of the patches is determined first. The method of Syrjala (1996), applied to weeds by Barroso et al. (2004), can be used to test whether patterns observed in 2 years are similar or not.…”

“…This straightforward and easy to understand method requires that the existence and spatial delineation of the patches is determined first. The method of Syrjala (1996), applied to weeds by Barroso et al (2004), can be used to test whether patterns observed in 2 years are similar or not. As this method provides only a yes ⁄ no answer, further exploration of the type of similarity or dissimilarity would seem useful to characterise the data more fully after this test has produced an outcome.…”

A computer vision approach for weeds identification through Support Vector Machines

“…Other approaches have used colour indices to distinguish vegetation material from background [9], Unlike the above approach our method tries to identify and classify a special weed seed, the avena sterilis ssp. Ludoviciana, which is one of the most widely distributed and abundant weed of cereals in Spain and other regions with Mediterranean climate and causes substantial losses in these crops [10,11]. The main problem concerning its classification is that during the herbicide treatment its colour and texture are undistinguishable with respect to the seed cereal (barley).…”