Integrated crop and pest management of winter oilseed rape (Brassica napus L.)

Abstract

The six major pests of winter rape in Europe: cabbage stem flea beetle (Psylliodes chrysocephala), cabbage stem weevil (Ceutorhynchus pallidactylus), rape stem weevil (C. napi), pollen beetle (Meligethes spp.), cabbage seed weevil (C. obstrictus) and brassica pod midge (Dasineura brassicae) are partly, sometimes fully, controlled by natural enemies. Crop management can either support or counteract this natural control. An objective of this European Union project No. QLK5-CT-2001-01447 was to design and test an Integrated Crop Management (ICM) system that aimed to be energy-efficient and high-yielding, giving a good economic net return yet with high natural control of pests and to compare it with a standard STaNdard (STN) farming system aimed to depict a modern way of growing rape. The two systems were compared in joint experiments in five countries. Non-inversion tillage was used to increase parasitisation of pollen beetle and seed weevil and activity-densities of ground beetles. Schedule spraying gave more control of stem weevil larvae than spraying to control thresholds. Differences in yield between the two systems were generally small. Where control thresholds were used, pesticide use was more than halved. Cost of soil tillage and the seed yield achieved were the main factors determining net return. Embedded energy of nitrogen fertiliser was more important than energy used for soil tillage. In the ICM system, total production costs, total energy use, labour and fuel costs were lower despite the need for one additional herbicide treatment; however, energy efficiency and nitrogen utilisation was a little lower indicating a need to better adjust nitrogen supply to yield level. A farming system based on the principles of ICM with non-inversion cultivation of soil can be recommended to farmers as a strategy to improve natural control of economically-important pests of winter oilseed rape, usually increase net return, decrease environmental impact and use less resources.

The potential of crop management practices to reduce pollen beetle damage in oilseed rape

“…Oilseed rape plants have potential to compensate for pollen beetle-related floral bud losses by producing new flower buds carried by either existing or new branches (Tatchell 1983;Nilsson 1994;Williams and Free 1979). Plant density, which can be strongly influenced by crop management through seed rates and sowing date, however, impacts the ability of the crop to compensate for bud losses, with higher planting densities generally leading to more restricted branching as there is less space for compensatory growth (Leach et al 1999;Momoh and Zhou 2001).…”

“…The insecticides that are routinely used to target pollen beetles and other OSR pests have detrimental effects on natural enemy populations and parasitism rates (Hanson et al 2015;Nilsson et al 2015;Jansen and San Martin 2014), meaning that integration of chemical and conservation biological control into IPM strategies is a major challenge (Williams 2004(Williams , 2006. These undesirable side effects, however, may be ameliorated in a several ways.…”

“…An integrated crop management strategy (ICM) for OSR, based on reduced tillage (to enhance parasitoid survival, and to reduce crop establishment-related energy use) and spraying to pest thresholds has been compared with 'standard' agronomic procedures (plough-based tillage and spraying to schedule) as part of an EU project (Nilsson et al 2015). Standard and ICM procedures were compared at sites in Germany, Poland, Sweden and the UK, in terms of their effects on pests, yields, energy use and crop production costs.…”

“…At the within-field scale, however, appropriate crop management also provides opportunities to improve beetle control, as crop management factors may affect plant growth and phenology (Valantin-Morison et al 2007), which in turn influence resource quality. As specific plant quality characteristics, for example relating to bud size or glucosinolate content, are known to play a role in pollen beetle host plant selection (Nilsson 1994;Cook et al 2006;Valantin-Morison et al 2007;Hervé et al 2014a), resource quality-mediated crop management effects are likely to influence pollen beetle abundance and damage in the field. Besides these effects, crop management is also likely to influence insect populations through microclimatic effects, and through variations in plant architecture, which may alter oviposition behaviour and food-seeking efficiency (Valantin-Morison et al 2007).…”

“…In early summer, just prior to harvest, an herbicide (usually glyphosate) is frequently applied as a desiccant to aid ripening, ease harvesting and control perennial weeds for the following crop. Generally, where plough-based establishment has been used, fewer herbicides are needed (Nilsson et al 2015). Similarly, a combination of seed treatment, and autumn and spring fungicide applications are normally required against diseases such as phoma stem canker (blackleg; Leptosphaeria maculans), sclerotinia stem rot (S. sclerotiorum), light leaf spot (Pyrenopeziza brassicae) and verticillium wilt (V. longisporum) (HGCA 2014).…”