Buenos Aires, Argentina
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Scursoni J.A.,Catedra de Produccion Vegetal | Satorre E.H.,Catedra de Cerealicultura
Crop Protection | Year: 2010

From their introduction in 1996, glyphosate resistant (GR) soybean cultivars have been rapidly adopted by farmers in Argentina and in other countries in the world. The high rate of adoption of this technology seems to be based on the simplicity of use provided by a single herbicide (glyphosate), its high efficacy to control many weeds and, the low costs of the technology relative to that used in conventional crops. During 2001-2002, 2002-2003 and 2003-2004 soybean growing seasons, field surveys and field experiments were performed with the aim of studying the effect of different glyphosate management strategies on the diversity of soybean weed communities, weed control, individual survival, fecundity and crop yield. In addition, the emergence pattern of three important weeds, Digitaria sanguinalis, Cyperus rotundus and Anoda cristata, was also studied. Both field surveys and field experiments were carried out on no-till soybean crops sown immediately after wheat or barley harvest (double cropped system). Experiments were set up in commercial soybean crops and consisted of different times of a single glyphosate application, two glyphosate applications and also the application of glyphosate plus a residual herbicide imazethapyr. A. cristata, D. sanguinalis, Stellaria media, Chenopodium album and Cyperus sp. were the most prevalent weeds recorded at pre-harvest of the soybean crops, showing regional constancy higher than 80% in both years. In three out of four field experiments, crop yield was not increased when glyphosate was applied twice compared with a single application of the herbicide. In addition there was a lower negative effect on weed species richness when glyphosate was applied once during the crop cycle than with two applications of glyphosate or glyphosate plus imazethapyr. D. sanguinalis escaped the glyphosate early treatment because of the long weed emergence period, while A. cristata and C. rotundus survived treatments due to their high individual tolerance. The results suggest that it is possible to manage glyphosate application to get high crop yield with a low impact on weed diversity, depending on the weed species and their abundance. © 2010 Elsevier Ltd.

Scursoni J.A.,Catedra de Produccion Vegetal | Cortada A.,Vivero Humus SA | Rezzano C.,National University of Rio Negro | Martinez E.,Instituto Nacional de Tecnologia Agropecuaria | And 3 more authors.
Crop Protection | Year: 2013

Raspberry (Rubus idaeus L.) is the most important crop in the (Andean Shire), an area situated at the south of Rio Negro Province in the south of Argentina. Organic berries production in this area increased significantly in the last ten years. Weed management in raspberry organic crops is performed by tillage. Excessive tillage can reduce weed species diversity and increase both soil erosion and production costs. Field experiments were carried out with summer and fall fruiting raspberry varieties within the periods 2005-06 and 2006-07 with the aim of studying the effect of different weeding times on (i) raspberry yield, (ii) fruit quality and (iii) weed community richness and abundance. The fruit harvest was carried out two or three times a week during all harvest period for each variety. In addition, fruit quality was assessed at different harvest times. From spring to the end of harvest weed cover and weed species richness were measured for each treatment. The results showed that the most frequent weed removal did not exceed the yield obtained with three weeding operations carried out during spring and summer. This meant an important reduction in cost production, with the advantage of maintaining weed diversity. The presence of weeds did not affect fruit quality. Summer fruiting variety was more competitive than fall fruiting variety. © 2012 Elsevier Ltd.

Scursoni J.A.,Catedra de Produccion Vegetal | Martin A.,Catedra de Produccion Vegetal | Catanzaro M.P.,Catedra de Produccion Vegetal | Quiroga J.,Catedra de Produccion Vegetal | Goldar F.,Catedra de Produccion Vegetal
Crop Protection | Year: 2011

Wild oat (Avena fatua L.) is the most troublesome weed in cereal crops in Argentina. With the aim of studying the effects of different herbicides, doses, and wild oat growth stage at application on weed control and crop yield, field experiments were conducted in wheat and barley crops during three growing seasons in the south of Buenos Aires Province, Argentina. Treatments were post-emergence applications of new herbicide, pinoxaden + cloquintocet mexyl (5%-1.25%), at doses that ranged from 20 g to 60 g a.i. pinoxaden ha -1, applied at two to three leaves and the beginning of tillering of wild oat. In addition, standard treatments were included and applied at the same wild oat growth stages. Diclofop methyl at 511 g a.i. ha -1 and fenoxaprop-p-ethyl at 55 g a.i. ha -1 were applied in barley. In wheat, diclofop methyl was replaced by clodinafop-propargyl + cloquintocet mexyl (24%-6%) at 36 g a.i. clodinafop-propargyl + 9 g cloquintocet mexyl ha -1 and in 2008/09 wheat experiments, iodosulfuron plus metsulfuron methyl (5%-60%) at 3.75 g a.i. ha -1 + 3 g a.i. ha -1 also was included. In both crops, pinoxaden at 30 g a.i. ha -1 and at higher rates, fenoxaprop-p-ethyl and clodinafop-propargyl gave the best control of wild oat. In 2006/07 wheat crops, treatments applied at tiller initiation provided better control than the early timing averaged across herbicides. However, wheat yield generally was greater with early application. In barley, wild oat control and crop yield were similar regarding time of application. Variations in crop yield were correlated with grain number m -2 both in wheat and barley, but relationships between both grain number and spikes m -2 and with grains per spike were identified only in wheat. © 2010 Elsevier Ltd.

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