TY - JOUR

T1 - Interactions between pre- and post-emergence weed harrowing in spring cereals.

AU - Brandsæter, L.O.

AU - Mangerud, K.

AU - Rasmussen, Jesper

PY - 2012

Y1 - 2012

N2 - Pre- and post-emergence weed harrowing were studied in spring cereals in different environments and with two types of harrows in Norway during 2004–2006. The objectives were to investigate interactions between pre- and post-emergence weed harrowing and the importance of harrow type. We hypothesised that pre- and post-emergence harrowing interact positively, that a combination gives more stable weed control effects than pre- and post-emergence weed harrowing used alone, and that a harrow type with bent tines is more aggressive and suitable on hard-packed soils than a harrow with strait tines. The results only supported the last of these hypotheses. Post-emergence weed harrowing controlled a certain percentage of the present weeds, and this percentage was not dependent on pre-emergence weed harrowing. On average, pre-emergence harrowing reduced weed density by 26% and weed biomass by 22%, while the average effect of post-emergence harrowing was 47% on weed density and 41% on weed biomass. The combined effect of pre- and post-emergence weed harrowing was 61% on weed density and 54% on weed biomass. The combination did not give more stable weed control effects than pre- and post-emergence weed harrowing used alone. Pre-emergence harrowing increased the average crop yield by 6.2%, post-emergence harrowing by 4.0% and the combined effect was 10%. Crop yield was mainly increased on hard-packed soils. Weed and crop responses varied strongly among experiments, but the efficacy of pre- and post-emergence weed harrowing was positively correlated across experiments. Weed species composition was of minor importance regarding weed control. The study indicates that one aggressive post-emergence cultivation may be as good as one pre-emergence and one less aggressive post-emergence cultivation. However, little is known about the interactions between cultivation at different crop and weed growth stages.

AB - Pre- and post-emergence weed harrowing were studied in spring cereals in different environments and with two types of harrows in Norway during 2004–2006. The objectives were to investigate interactions between pre- and post-emergence weed harrowing and the importance of harrow type. We hypothesised that pre- and post-emergence harrowing interact positively, that a combination gives more stable weed control effects than pre- and post-emergence weed harrowing used alone, and that a harrow type with bent tines is more aggressive and suitable on hard-packed soils than a harrow with strait tines. The results only supported the last of these hypotheses. Post-emergence weed harrowing controlled a certain percentage of the present weeds, and this percentage was not dependent on pre-emergence weed harrowing. On average, pre-emergence harrowing reduced weed density by 26% and weed biomass by 22%, while the average effect of post-emergence harrowing was 47% on weed density and 41% on weed biomass. The combined effect of pre- and post-emergence weed harrowing was 61% on weed density and 54% on weed biomass. The combination did not give more stable weed control effects than pre- and post-emergence weed harrowing used alone. Pre-emergence harrowing increased the average crop yield by 6.2%, post-emergence harrowing by 4.0% and the combined effect was 10%. Crop yield was mainly increased on hard-packed soils. Weed and crop responses varied strongly among experiments, but the efficacy of pre- and post-emergence weed harrowing was positively correlated across experiments. Weed species composition was of minor importance regarding weed control. The study indicates that one aggressive post-emergence cultivation may be as good as one pre-emergence and one less aggressive post-emergence cultivation. However, little is known about the interactions between cultivation at different crop and weed growth stages.

U2 - 10.1111/j.1365-3180.2012.00925.x

DO - 10.1111/j.1365-3180.2012.00925.x

M3 - Journal article

VL - 52

SP - 338

EP - 347

JO - Weed Research

JF - Weed Research

SN - 0043-1737

IS - 4

ER -