ABSTRACT: Italian ryegrass (Lolium multiflorum Lam.) is a troublesome weed widely found in temperate Brazilian fields with several herbicide-resistant populations. Soil seed bank is the main source of future infestations and can be strongly affected by agricultural practices, such as crop rotation and tillage system. Therefore, this study evaluated the long-term effects of different crop rotation and tillage systems on the seed bank of Italian ryegrass. Data were collected in 2012 and 2013 in a field managed since 1985 under conventional-tillage and no-tillage and subjected to three cropping systems (monoculture, total, and partial rotation) compared to the control plot. The samples were collected at three soil depths (0-5, 5-10, and 10-20 cm) using a cylindrical soil sampler, and infestations in the field were evaluated with a sample frame of 1 m2. All cropping systems reduced the soil seed bank of Italian ryegrass, regardless of soil management and sampling depths comparing to the control plot. Total and partial rotation were more effective than soil tillage to reduce the seed bank. A larger number of seeds was observed on the surface layer (0-5 cm) for all cropping systems with more uniform distribution in the soil profile in conventional-tillage. Infestation of Italian ryegrass was greater for monoculture under no-tillage in both years, whereas in total and partial rotation, regardless of soil tillage, infestations remained below 40 seedlings m−2. Thus, strategies to reduce the soil seed bank and infestations of Italian ryegrass should focus on cropping systems with crop rotation and no-tillage.

A amostragem é um dos procedimentos básicos indispensáveis ao manejo integrado de pragas. Neste experimento, comparou-se a capacidade de coleta de dois métodos de amostragem da lagarta-da-soja (Anticarsia gemmatalis Hueb., 1818) e do percevejo-verde-pequeno (Piezodorus guildinii Westw., 1837) na cultura da soja semeada em três espaçamentos entre linhas (0,30; 0,40 e 0,50m). Foi utilizado o delineamento inteiramente casualizado, com dez repetições (amostragens), em esquema fatorial 2x3; utilizaram-se dois métodos de amostragem (pano-de-batida e pano-vertical) e três espaçamentos entre linhas. A população de lagarta-da-soja e de percevejo-verde-pequeno foi avaliada nos estádios V8 e R6, respectivamente. Para lagartas, os resultados indicam maior eficiência do pano-vertical em relação pano-de-batida. Nos menores espaçamentos, o pano-vertical não deixou clara sua maior capacidade de coleta de percevejos, como observado para lagartas. Estes resultados demonstram que são necessárias pesquisas visando a aprofundar a avaliação dos métodos de amostragens de pragas da soja cultivada em diferentes espaçamentos.

Sampling is a key component in the Integrated Pest Management. In this studit was compared the colleting capacity of two sampling methods for caterpillar (Anticarsia gemmatalis Hueb., 1818) and stink bug (Piezodorus guildinii Westw., 1837). An experiment was carried out in soybean sown in three spacing (0.30, 0.40 and 0.50m). The experiment design was a completely randomized design with ten repetitions (sampling) in a 2x3 factorial. The population of velvetbean caterpillar and stink bug was evaluated in two sampling methods (beating cloth and vertical beat sheet) and three row spacing, at V8 and R6 stages, for caterpillar and stink bug, respectively. Results showed greater efficiency of the vertical beat sheet compared with beating cloth in colleting caterpillar. In the smaller spacing, the vertical beating cloth did not clarify its greater capacity of colleting bugs, as observed for caterpillars. These results show that more studies are necessary to evaluate sampling methods of insects in soybean using different plant spacing.