Non-chemical control of cabbage stem flea beetle

All pests and crops are responsive to the environment. Understanding this response provides opportunities for integrated pest management (IPM). Our research has identified the key components of a cabbage stem flea beetle (CSFB) IPM strategy and used a traffic-light code to indicate the current reliability for control in oilseed rape.
Integrated pest management of cabbage stem flea beetle in oilseed rape (research page) Read the news release about this research Find out about the follow-up project (2020-23) Cabbage stem flea beetle home page

CSFB IPM traffic-light key

Most reliable control, some further research required

Moderate control, further research needed

Uncertain/unproven control, significant further research essential

All periods

 Natural enemies – It is important to account for natural pest enemies. Pesticide applications (especially broad-spectrum pyrethroids) and intensive tillage are likely to have a negative impact on natural enemy populations 

 Novel insecticides/biopesticides – Although this may become part of the solution, the impact of potential approaches is currently far from clear

Pre-sowing

Trap crops – Oilseed rape volunteers can act as a trap crop and divert CSFB away from adjacent cash crops. In trials, the approach reduced adult CSFB infestation (by up to 88%) and damage (by up to 76%). It also resulted in higher plant populations (by up to 56%) and reduced larval populations (by up to 69%). However, benefits were variable and not always observed. It is likely that relatively large areas of adjacent trap crops are more likely to deliver benefits, especially if left in place until after the bulk of CSFB migration has occurred. Sown trap crops and cover crops may also be effective

Seed treatments – When available, these are likely to provide moderate control and cost more than pyrethroids

Varieties – There is no clear evidence to suggest that varieties differ in susceptibility or attractiveness to CSFB. This area, along with other characteristics (e.g. associated with vigour), needs further investigation

Stubble management – Fields in which oilseed rape has not been grown recently or nearby are likely to have relatively low CSFB starting pressures. The presence of cereal stubble/straw could make it harder for the pest to locate emerging oilseed rape, but robust trial data is sparse

Sowing

Soil moisture – Sufficient soil moisture levels during crop emergence are particularly critical

Sow date – Early sowing increases the likelihood that the crop will emerge before CSFB migration begins. Late sowing (second half of September) may result in the crop emerging after the migration peak – such crops are also associated with reduced larval pressures

Seed rate – Generally, in terms of yield, increasing the seed rate beyond that needed to achieve optimal plant populations – 25–40 plants/m2 – results in little benefit, unless conditions are dry during establishment. Interestingly, higher seed rates are associated with greater larval numbers per hectare, which could build pest populations across seasons

Companion crops – Anecdotal reports suggest several companion crop species could play a role in CSFB management, through attracting the pest, improving soil or masking the crop from CSFB. Limited research has also detected significantly less damage in crops (two-leaf and five-leaf stage) companion-cropped with either a berseem/clover mix or mustard

Establishment method – Low-soil-disturbance-establishment methods are associated with more moisture-retentive soils and higher levels of natural pest enemies. There is little robust evidence to show that this translates to a definitive reduction in CSFB damage, but anecdotal evidence and limited trial results are encouraging

Establishment

Organic amendments – The addition of organic amendments around establishment could reduce CSFB damage, but reports are largely anecdotal and supporting trial data is sparse. Effects observed could be due to improvements in crop growth or the reduction of CSFB infestation (e.g. by masking the crop or deterring the pest)

Autumn/winter

Managed defoliation – CSFB larvae are far more likely to be present in leaf petioles than in the stem. Managed defoliation reduced larval numbers significantly in trials (by 23–55%), with late defoliation, before stem extension, most effective. Linked on-farm trials found that sheep grazing and topping reduced larval numbers by 51% and 25%, respectively. However, researchers did not detect significant yield increases in crops with reduced larval populations. Interestingly, defoliation also decreased the severity of phoma stem canker to levels equivalent to a fungicide spray

Spring

Enhance crop tolerance – Crop management that enhances crop resilience (e.g. through nutrition and plant growth regulation) could make the crop more tolerate to larval damage. However, robust evidence is lacking

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