New approaches to managing cabbage stem flea … approaches to managing cabbage stem flea beetles in oilseed rape Simon Kightley NIAB This project has received funding from the European

New approaches to managing cabbage stem flea beetles in oilseed rape

Simon Kightley

NIAB

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 634179.

EMPHASIS Effective Management of Pests and Harmful Alien Species - Integrated Solutions

Psylliodes chrysocephala

Psylliodes chrysocephala

Public enemy

Number one!

The background

• ADAS (1984) describe CSFB as a damaging pest in Berkshire, Buckinghamshire, Cambridgeshire, Essex and Northamptonshire, Oxfordshire and parts of Warwickshire

• Subsequently controlled with Gamma HCH seed treatments until banned in 1999

• One season with no effective seed treatment

• Subsequently controlled by neonicotinoid seed treatments until banned in 2014

2014/15, 2015/16 & 2016/17

Three years of contrasting experiences……..

2014/15, 2015/16 & 2016/17

Three years of contrasting experiences……..

And most of them very unpleasant and

depressing!

2014/15 • Neonic ban coinciding with high CSFB

numbers after increasingly warm winters (3oC is critical for egg laying and larval development)

• Poor conditions for establishment in central East Anglia – cool, dry, early September

• Extensive predation by CSFB adults on later sown crops

• No successful establishment in trials after 27th August in Cambridge area – but no farm survey

Adult damage to crop establishment before, during and after emergence

Trial losses in Autumn 2014

Key Successful establishment Successful farm crop Partial establishment Complete failure

NIAB, Staughton drilled 17-20 Aug

NIAB, Hardwick Drilled 8 Sept

LSPB, Girton 27-29 Aug

LSPB, Impington 4-8 Sept

Saaten Union, Cowlinge 2-4 Sept

Saaten Union, Wickhambrook 24 Aug

KWS, Barley 29 Aug Re-drilled 17 Sept Failed

NIAB, Bottisham Farm crop 15 Aug, good Early sowing 19 Aug, OK Main sowing 29-31, failed Site written off (4080 plots)

NIAB, Trumpington 2 Sept Effective write off. Site maintained by transplants for disease obs.

NIAB HQ 22 Aug - OK 4 fields 2-7 Sept Fragments only remaining, supplemented by transplants

ADAS Boxworth Drilled 22 Aug; Re-drilled 8 Sept. Failed

Trial losses in Autumn 2014

Key Successful establishment Successful farm crop Partial establishment Complete failure

NIAB, Staughton drilled 17-20 Aug

NIAB, Hardwick Drilled 8 Sept

LSPB, Girton 27-29 Aug

LSPB, Impington 4-8 Sept

Saaten Union, Cowlinge 2-4 Sept

Saaten Union, Wickhambrook 24 Aug

KWS, Barley 29 Aug Re-drilled 17 Sept Failed

NIAB, Bottisham Farm crop 15 Aug, good Early sowing 19 Aug, OK Main sowing 29-31, failed Site written off (4080 plots)

NIAB, Trumpington 2 Sept Effective write off. Site maintained by transplants for disease obs.

NIAB HQ 22 Aug - OK 4 fields 2-7 Sept Fragments only remaining, supplemented by transplants

ADAS Boxworth Drilled 22 Aug; Re-drilled 8 Sept. Failed

The warning signs had been there.

Teversham – Autumn 2012

Cruiser treated seed – Further up the field, breeders’ trials, with untreated seed, survived well.

2015/16 • Much better conditions for establishment – good

rainfall, warmer

• High adult beetle numbers

• Losses of commercial crops (see survey)

• Warm winter prolonged egg laying and larval development

• Many larval infested crops branched and stunted

• Backward, pigeon grazed crops affected by late frosts

• Low yielding year

2016/17

• Dry September


• Losses of commercial crops (see survey)

• Cool October/November reduced egg laying/larval development

• Few larvae reported in petioles

• Surviving crops developed well in normal April period

• Reduced CSFB pressure for Autumn 2017?

The pest

• What do we really know about the pest?

• Is it out of control?

• Insecticide resistance

Cabbage stem flea beetle (Psylliodes chrysocephala) (Dr Sam Cook – Rothamsted Research)

Life cycle : univoltine

Late Aug- Oct

Adults move into new crop, mate feed on leaves causing ‘shot-

holing Aug - Feb

Eggs laid at base of plant when warm & humid

Late Aug – March

Larvae feed in leaf petioles, 3rd instars feed in

stem Dec – May

Larvae drop to the ground ; Pupate in

the soil for c. 3 months

May-July

Adults emerge, feed on leaves,

pods

July – Sept

Aestivate in sheltered areas

Larval feeding damage

• Has really only come to the fore in spring 2016

• High levels of infestation widely reported • Apparently healthy crops failing to grow

away, in cool, grey, early spring conditions


Larval damage to growing point

Short, highly branched plants Delayed flowering Increased vulnerability to other pests (pigeons, pollen beetles)


• Larvae are pretty well immune to sprays once they are feeding inside the plant

• Assessing yield loss is highly speculative • Yield loss likely to be worse in low

populations – just a numbers game

What we don’t know

• Dispersal distance of the adults

• Whether a couple of hard winters might knock the population right back

• What sort of rape-growing moratorium and over what sort of area would be needed to do any good: County? Region?

Dispersal by grain trailer

Encouraging news from Sweden?

Harvest year – 1975-2014

CSFB population cycles in Skåne (Southern Sweden)

Larv

ae p

er p

lant

Source: Jordbruks verket - Sweden

Update from Skåne

Harvest year – 1983-2015

Larv

ae p

er p

lant

CSFB population cycles in Skåne (Southern Sweden)

Source : Jordbruks verket - Sweden

2015/16

Improved strategies for Autumn 2015

For trials: • Early-sown neonicotinoid seed-treated surround

crops (Experimental Licence) • Treated seed in pathways (tramlines) and in strips

through trials • Fine seedbed preparation • Starter fertiliser • Early use of neonic insecticide spray (Insyst) • Regular and frequent pyrethroid insecticide

sprays (Not good for beneficial insects!!!) • Irrigation (where available) • Insect netting

Help from the UK Government!

Acknowledgement of the serious threat to the oilseed rape crop:

• A derogation for limited use of neonic seed treatment in worst affected counties

• A derogation for use of neonic insecticide crop sprays

Demonstration plots - 2016


Established under fine-mesh, insect netting

Better establishment

• Better soil moisture and warmer temperatures than autumn 2014.

• Better luck with establishment locally.

BUT

• More widespread reports of farm crop failures

• More reports of neonicotinoid seed treatments failing to control CSFB

• Observations of pre-emergence herbicides holding crop back

• Huge problem with larvae

Pre-emergence herbicide effect

• Observations that our Clearfield trial at Hinxton, grown without pre-ems, got away better than the rest of our trials

• We used:

– BANASTAR (dimethenamid-p, metazachlor, quinmerac)

– CIRRUS (clomazone)

NIAB TAG Crowd Sourcing Survey

Using farmer on-line responses to map the range and severity of the flea beetle problem:

• Is it spreading?

• Is it date dependent?

• Is it weather dependent?

• Is it affected by establishment method?

• Do ‘neonic’ seed treatments still work?

• East Anglia/Bucks./Herts. is the main area affected by cabbage stem flea beetles. • Later sowings most at risk.

• Neonicotinoid seed treatments were no guarantee of protection. • Regret not asking for reduced or zero plantings.

Survey responses

Data summary

0

2

4

6

8

10

Nu

mb

er o

f re

spo

nse

s/d

ay

Sowing date

Crop damage intensityInsignificant Low Moderate Severe Very Severe

Combined damage score No. of obs.

Variety typeMixed 25.3 30Conventional 25.4 78Hybrid 27.7 73Establishment methodAutocast 15.4 7Plough 21.4 33Non-inversion 24.1 63Subcast 27.7 32Direct drill 33.5 46Seed treatmentOther 22.3 65None 26.3 95Neonicotinoid 36.2 21

A summary of other data










Also new for Autumn 2015

Experiments with companion crops

Trial locations

Sutton Scotney, Hampshire

Morley, Norfolk

Hinxton, Cambridge

Seed rate x companion crop experiment

Companion crop

OSR seed rate/m2 60 80 100 120

No companion crop N60 N80 N100 N120 Mixture A A60 A80 A100 A120 Mixture B B60 B80 B100 B120 Mixture C C60 C80 C100 C120

OSR variety: CHARGER A = Insect deterrent: Fenugreek B = Insect attractant: Pak choi/Chinese cabbage/salad rocket/linseed C = Insect neutral: Berseem clover/crimson clover/Persian clover/common vetch Replicates: 4 Sites: 3 – Cambridge (Hinxton), Morley, Sutton Scotney

Companion cropping

Generalised plot layout

12 m

2 m

The aim was to achieve well defined rows of oilseed rape in a carpet of non-hardy, companion species plants.

Separate sowings of: 12 rows companions, 4 rows oilseed rape

Companion cropping (Sutton Scotney)

Fenugreek Rocket, Pak Choi,

Chinese cabbage, Linseed

Common vetch Crimson clover Berseem clover Persian clover

Companions – a closer look

Fenugreek Brassica - linseed mix

Legume mix

Damage observations (1 good; 5 bad)

29/09 15/10 29/09 15/10OSR 60 3.8 4.3OSR 80 3.5 3.8OSR 100 3.3 3.5OSR 120 3.8 3.3 3.6 3.7A OSR 60 4.0 3.3A OSR 80 3.5 2.8A OSR 100 3.5 3.3A OSR 120 3.5 3.0 3.6 3.1B OSR 60 2.3 1.0B OSR 80 2.0 1.0B OSR 100 2.3 1.0B OSR 120 2.5 1.0 2.3 1.0C OSR 60 3.5 2.8C OSR 80 3.3 2.5C OSR 100 3.0 2.5C OSR 120 3.3 2.5 3.3 2.6

Trt x sdrt Trt meansCambridge obs.

Treatment name

Treatments:

OSR only

OSR and Fenugreek

OSR and exotic brassica/ linseed mix

OSR and legume mix

Damage observations (1 good; 5 bad)

29/09 15/10 29/09 15/10OSR 60 3.8 4.3OSR 80 3.5 3.8OSR 100 3.3 3.5OSR 120 3.8 3.3 3.6 3.7A OSR 60 4.0 3.3A OSR 80 3.5 2.8A OSR 100 3.5 3.3A OSR 120 3.5 3.0 3.6 3.1B OSR 60 2.3 1.0B OSR 80 2.0 1.0B OSR 100 2.3 1.0B OSR 120 2.5 1.0 2.3 1.0C OSR 60 3.5 2.8C OSR 80 3.3 2.5C OSR 100 3.0 2.5C OSR 120 3.3 2.5 3.3 2.6

Trt x sdrt Trt meansCambridge obs.

Treatment name

TreatmentName 12/1 26/1 12/1 26/1OSR 60 3.5 3.5OSR 80 3.3 3.3OSR 100 3.5 3.5OSR 120 3.5 3.3 3.5 3.4A OSR 60 3.3 3.0A OSR 80 3.3 2.8A OSR 100 3.5 3.0A OSR 120 3.3 3.0 3.4 3.0B OSR 60 3.0 3.0B OSR 80 3.0 2.8B OSR 100 3.0 3.0B OSR 120 3.0 2.3 3.0 2.8C OSR 60 3.3 3.0C OSR 80 3.3 2.8C OSR 100 3.3 2.5C OSR 120 3.3 2.8 3.3 2.8

Morley obs.Trt x sdrt Trt means

-5

0

5

10

15

20

25

30

35

40

45

Pe

rce

nta

ge

da

ma

ge

(n

ea

rest

5%

)

Percentage CSFB damage

Fenugreek Brassica and linseed mix Legume mix OSR

Working with Reading University and Rothamsted Research (Duncan Coston)

Control of companion species

• No killing frosts in 2015/16 winter

• Several herbicide applications were tried but were rather ineffective post-Christmas and limited by label regulations

• Brassica/linseed mix was particularly resilient – crowded-out the OSR

Yield - No CSFB pressure

3.0

3.3

3.5

3.8

4.0

Yie

ld (t

/ha)

Yield (t/ha) Sutton Scotney - 2016

Yield - light CSFB pressure

1.0

1.3

1.5

1.8

2.0

Yie

ld (t

/ha)

Yield (t/ha) Morley - 2016

Yield - high CSFB pressure

Cambridge

NO YIELD!

Back to beetle biology

• New attempts to monitor beetle dispersal and migration in the approach to harvest 2016

• We favour yellow stick traps

Monitoring the next generation of CSFB

The beetles were staying in the crop

In the canopy On the ground

Pod damage

Conclusions from 2016

• Establishment is helped by early sowing, good seedbeds, warmth and rain.

• This does not guard against subsequent larval infestation.

• Neonics were a tool but no longer the answer. • Early sown, treated/sprayed trap cropping can

help. • Companion cropping can play a part. • Pre-emergence herbicides can hold crop back • And yes, back to higher seed rates!

And so to 2016/17

• Some breeders moving their nurseries away from the Cambridge area

• We maintained a large presence of research and commercial breeders’ and agrochemical trials at Hinxton (Cambs) – 34 ha

• Weather : DRY. A few showers to germinate the seed but not enough for good growth

• The drought affected much of south-east England and has complicated the flea beetle story

Government help withdrawn!

• No derogation for neonic seed treatments

• No derogation for neonic insecticide sprays

2016/17 • Dry September


• More losses of commercial crops (see survey)

• BUT:

• Cool October/November reduced egg laying/larval development

• Fewer larvae reported in petioles

• Surviving crops developed well in normal April flowering period

• Reduced CSFB pressure for Autumn 2017?

Monitoring the migration

05

101520253035

5 6 8 9 12 13 15 16 19 20 23 26 27

Ave

rag

e C

SF

B p

er t

rap

Date in September

CSFB trapping - Brooms Barn, 2016

Monitoring the migration



More success for insect netting

Crowd sourcing - Autumn 2016

Companions for 2016/17

CropMix

code

1000 seed

weightseeds/m2

seed wt/m2

Plot size

Packet size

OSR 4.5 60 0.27 20 5.4OSR 4.5 90 0.41 20 8.1OSR 4.5 120 0.54 20 10.8CompanionsFenugreek A 12.0 250 3.00 20 60.0Pak choi B 1.9 80 0.15 20 3.0Chinese kale B 4.0 80 0.32 20 6.4Choi sum B 2.4 80 0.19 20 3.8Rocket C 1.4 125 0.18 20 3.5White mustard C 7.4 125 0.93 20 18.5Buck wheat D 33.4 250 8.35 20 167.0

14/12 2016 Cambridge - Fenugreek

14/12 2016 Cambridge – Brassica mix

14/12 2016 Cambridge – Buck wheat

With oilseed rape plots in foreground

14/12/2016 Cambridge – Mustard

and 34 ha of weeds and desolation

But what have we here?!

Autumn 2016 – Morley - damage Trt. No.

WOR sdrt Companion mix 09/09 14/09 19/09 26/09 07/10 12/10

1 60 - 1.0 2.7 2.7 3.3 2.0 1.02 90 - 1.0 3.0 2.7 3.7 2.3 1.33 120 - 1.0 3.0 3.0 3.3 2.3 1.04 60 Fenugreek 1.0 2.7 2.7 2.7 2.0 1.05 90 Fenugreek 1.0 2.7 2.3 2.7 2.0 1.06 120 Fenugreek 1.0 2.0 2.3 3.0 2.0 1.07 60 Chinese brassicas 1.0 2.7 3.0 3.3 2.7 2.38 90 Chinese brassicas 1.0 2.3 3.0 3.3 2.7 2.09 120 Chinese brassicas 1.0 2.7 3.0 3.7 3.0 1.710 60 Mustard & Rocket 1.0 1.7 1.7 2.0 2.3 1.011 90 Mustard & Rocket 1.0 1.7 2.0 2.0 2.3 1.312 120 Mustard& Rocket 1.0 2.0 2.0 2.0 2.0 1.313 60 Buck wheat 1.0 1.7 2.0 3.0 3.0 1.014 90 Buck wheat 1.0 2.7 3.0 3.0 2.7 1.015 120 Buck wheat 1.0 2.7 2.7 3.0 3.0 1.0

1.0 2.4 2.5 2.9 2.4 1.3Averaged over treatments

Observations on the 2017 companions

• All except Rocket (Eruca sativa) proved susceptible to the frost

• The white mustard/rocket mix appeared to have potential for protecting the crop

• But:

• If controlled after the winter, will stunt the OSR and reduce yield potential

• Much work still to do

Good companion-bad companion

White mustard

Salad rocket

OSR stunted in mustard mix

Overall conclusions

• Cabbage stem flea beetles remain a huge threat to the oilseed rape crop

• Threat is greater for later sowings

• Attention to improved conditions for rapid germination is important

• No immediate promise of chemical control

• Successive cold winters may help

• Companion crops have potential and white mustard seems to be the best candidate

• More work needed

Thank you for listening!

Documents

New approaches to managing cabbage stem flea … approaches to managing cabbage stem flea beetles in oilseed rape Simon Kightley NIAB This project has received funding from the European