Conventional- and conservation-tillage systems influence emergence periodicity of annual weed species in canola

Abstract

Variation in spring emergence periodicity (both before and after crop seeding) of summer annual weeds is a potentially exploitable attribute that may be applied to weed management in canola. Tillage intensity, which is decreasing in the Great Plains of North America, may influence emergence periodicity of summer annual weeds. Emergence periodicity of common lambsquarters, field pennycress, green foxtail, redroot pigweed, wild buckwheat, wild mustard, and wild oat were monitored during the spring of 2000 in 17 producers' canola fields across southern Manitoba, Canada. The fields represented a region of approximately 2 million ha and included a broad range of soil types, agronomic practices, environmental conditions, and seedbank distributions. Fields were grouped into one of two broad tillage classifications (conventional or conservation). For most species, except redroot pigweed and wild mustard, conservation tillage promoted earlier emergence than conventional tillage in terms of both thermal and chronological time. The differences were significant even though there was only a limited range of tillage intensity for the two tillage classes within this region. Onset of canola crop emergence preceded that of all but one weed species in the conservation-tillage fields and five weed species in the conventional-tillage fields. This suggests that canola seeded in conservation- vs. conventional-tillage systems may have a competitive advantage by way of an earlier relative time of crop emergence. The influence of tillage system on weed emergence periodicity is likely due to the influence of tillage on the vertical origin of weed seedling recruitment because measurements of soil temperature and soil moisture did not help to fully explain the differences in emergence periodicity between tillage systems. The results from this study will facilitate weed control timing decisions in canola and provide validation data for weed emergence models.

Emergence dynamics of barnyardgrass and jimsonweed from two depths when switching from conventional to reduced and no-till conditions

“…Conversely, chisel plowing retains them nearer the surface facilitating germination and emergence, thereby increasing the requirement of management inputs to control them (Ball, 1992;Vasileiadis et al, 2007). Other studies indicate that weeds increase after several years of reduced tillage because of increased seed accumulation at the soil surface, the lack of disruption of underground vegetative reproductive organs (Cardina et al, 1991;Bàrberi et al, 1998) and changes in timing of weed emergence compared with inversion tillage (Bullied et al, 2003). Indeed, the timing of weed seedling emergence in the field varies depending on, individual species germination requirements, seed burial depth, soil disturbance (Roberts & Feast, 1972) and environmental conditions (Forcella, 1992).…”

The biology of Canadian weeds. 138. Kochia scoparia (L.) Schrad.

“…Its rapid early germination is important for exploiting the limited spring soil moisture in arid to semiarid regions (Eberlein and Fore 1984;Dyer et al 1993b). In a field study in southern Manitoba, about 80% of kochia seedlings had emerged before even 10% of the seedlings of eight other annual weed species common to the Prairies typically emerge ( Bullied et al 2003;Schwinghamer and Van Acker 2008). Kochia emergence, however, is deterred if soil water availability is low, which may occur more frequently in saline soils.…”

Germinação de Borreria densiflora var. latifolia sob condições controladas de luz e temperatura

“…Ainda, o conhecimento de fatores como luz e temperatura e sua interação, os quais influenciam os processos de germinação e dormência, abre a possibilidade para o desenvolvimento de modelos que predizem a emergência, uma ferramenta útil para otimizar as decisões de manejo de plantas daninhas, não só a respeito da tática de emprego (controle mecânico ou químico, tipo de herbicida, resisual, etc. ), como também da oportunidade, para implementar tal medida (Bullied et al, 2003;Myers et al, 2004). Observações recentes de campo relatam a ocorrência de altas infestações da planta daninha vassourinha-de-botão e a dificuldade de ser controlada em áreas produtoras de soja, no norte do Estado do Tocantins, e em áreas produtoras de cana-de-açúcar, nos Estados de Goiás e Maranhão.…”