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Tesis:

Tratamientos localizados contra poblaciones de Avena sterilis L. presentes en cultivo de cereal en la región centro de España.

  • Autor: BARROSO PEREZ, Judit

  • Título: Tratamientos localizados contra poblaciones de Avena sterilis L. presentes en cultivo de cereal en la región centro de España.

  • Fecha: 2004

  • Materia: Sin materia definida

  • Escuela: E.T.S. DE INGENIEROS AGRONOMOS

  • Departamentos: PRODUCCION VEGETAL: FITOTECNIA

  • Acceso electrónico:

  • Director/a 1º: FERNANDEZ QUINTANILLA GALLASTEGUI, César

  • Resumen: Avena sterilis L. is present in many fieldis throughout the Mediterranean region. Typically occurring in patchy distributions at the fíeid scale. lf weeds are patchy, the environmental impact of weed control and imput costs can be reduced through site specific weed management (SSWM). However, the effectiveness of different sampling methods, the temporal and spatial stability of weed distributions all affect the cost effectiveness of SSWM in central Spain. These factors were quantified as part of this proyect. Field experiments were conducted to compare: lour methods used to detect Avena sterilis patches; to determine their temporal and spatial patch dynamic; and to evaluate a trí-annual plan of site specific Avena sterilis management. Evaluation of the sampling methods was conducted over two seasons in two fields of approximately two hectares each. Although the four sampling methods evaJuated (Scoring panicie density from the ground, Scoring panicie density from the combine, Counting panicie contacts and Counting seed rain on the ground) showed similar descriptions of the spatial distribution of Avena sterilis, the cost of collecting the data deiffered widely (from 9 euros/ha to 750 euros/ha). The sampling cost was found to be critical in determining the herbicíde application strategy and the optimum sampling method. Defining the location of weed patches from the combine was calculated to be a relatively inexpensive and reliable method for the creation of weed management maps to be used for patch spraying in the folíowing season. The spatial distribution of Avena sterilis was sampled in two fieldis in a cropping system based on a winter barley monoculture with minimum tillage practices. Half rate of imazamethabenz Avena sterilis specific herbicíde was applied annually to the fields. One field (0.5 ha) was sampled over a five year period using a 1 Om x 1 Om grid and the other (1.8 ha) was sampled over a three year period using a l2m x 25m. Using the Syrjala test of stability the distribution of Avena sterilis was persistent but not stable in bath fíelds. The populations decreased faster when the infestation went from high or moderate density, than when it werit from a low density. Under the conditions present in the experiment, it was possible to reduce heavy weed patches (up to 1200 seedlings/m2) down to relatively safe leveis (18 seedlings/m2). However, under adeverse environmental conditions, half rates of the herbicide failed to control the weed populations adequately. The evaluation of the tri-annual A, sterílis management plan and its comparison with the two broadcast application strategies was made in a field of approximately two hectares following a complete factorial experimental design with four blocks and six repetítions per block. The results varied slightly within the years but, in general, the highest control levels were obtained with the broadcast application treatments at full dose. Using half doses reduced Avena sterilis control. This effect was minly atiributed to the poor performance of low doses with high weed densities. The site specific approach resulted in the highest variability in the control, with some control failures in areas of low density of Avena sterilis. In acidition, the profitability of site specific Avena sterilis management was examined by a simulation model. Net retums of site specific Avena sterílis management were ibund to be influenoed by the interaction among the percentage of field infested, the pattern distribution and the weed sampling andilor herbicide spraying resolution. Net returns increased when both the proportion of field infested and the number of patches decreased. The highest net returns were obtained with the coarsest resolutions (12 m) due to the high current technology costs. Future research efforts should focus on diminishing this technology cost to make finer weed detection/herbicide treatment profitable, and so improving the SSWM profitability.