Aphid control in leafy salads: trials in SCEPTREplus

Transcription

1 Aphid control in leafy salads: trials in SCEPTREplus Rosemary Collier, Andrew Jukes, Marian Elliott Warwick Crop Centre, School of Life Sciences, University of Warwick

2 Aphids the problem Four species regularly infest lettuce: Nasonovia ribisnigri major contaminant Myzus persicae virus transmission? Macrosiphum euphorbiae how important? Pemphigus bursarius lettuce root aphid Two specialists and two generalists Other species within the remit of leafy salads?

3 Currant lettuce aphid (Nasonovia ribisnigri) Major contaminant Host plant resistance commercial varieties available But resistance-breaking strains of aphid are around No evidence of insecticide resistance having an impact on a field scale? Difficult to access the aphids as they are well-hidden systemic insecticides more effective

4 Peach-potato aphid (Myzus persicae) Generalist - so completes its life-cycle on a range of crops Sometimes a contaminant and may be the main vector of virus Viruses can be significant in terms of loss of yield and quality unclear which aphid-transmitted viruses are likely to be a major threat (FV 427) Effective approaches to controlling virus transmission might be different to those for controlling contaminants Insecticide resistance is a major factor to be considered in management

5 Peach-potato aphid Steve Foster Esterase resistance (to OPs etc) has virtually disappeared now the selection pressure has been reduced

6 Peach-potato aphid Steve Foster

7 Peach-potato aphid Steve Foster

8 Dynamic situation - changes in Myzus persicae clones in Scotland Data from Gaynor Malloch (James Hutton Institute) & Brian Fenton (SRUC)

9 Lettuce root aphid (Pemphigus bursarius) Affects yield rather than quality Well-controlled by neonicotinoid seed treatments Sources of host plant resistance available but not in current varieties? Immigration predictable day-degree forecast

10 Monitoring and forecasting

11 Accumulated day-degrees above 4.4 C Monitoring and forecasting Day-degree forecasts currant lettuce-aphid, lettuce root aphid Feb 15-Feb 1-Mar 15-Mar 29-Mar 12-Apr 26-Apr 10-May 24-May 7-Jun 21-Jun 5-Jul 19-Jul Cornwall Nottinghamshire Yorkshire Kent South Lincs Suffolk Start of currant-lettuce aphid migration Peak of currant-lettuce aphid migration Start of lettuce-root aphid migration

12 Insecticide use on lettuce 2015 Pesticide Usage Survey Report 270 Outdoor Vegetable Crops In the United Kingdom 2015

13 Spray hectares Insecticide use on lettuce Pesticide Usage Survey Report 270 Outdoor Vegetable Crops In the United Kingdom ?

14 SCEPTRE trials and FV 445 (carrots) SCEPTRE Code Cabbage aphid Currant-lettuce aphid Willow-carrot aphid AHDB9964 Biological YES NO? NO NO NO NO NO NO NO AHDB9968 Biological NO YES NO NO NO YES AHDB9948 Conventional YES YES NO? YES YES YES AHDB9966 Conventional YES YES YES YES? YES YES YES AHDB9943 Conventional YES YES YES YES NO? YES YES YES YES AHDB9930 Conventional YES YES AHDB9933 Conventional YES AHDB9951 Conventional YES NO no efficacy YES statistically-significant control? unclear result

15 Laboratory trials spring 2018 Conventional insecticides Code Water volume L/ha Timing Untreated AHDB D1 Benevia 10OD 300 D1 AHDB D1 AHDB D1 AHDB D1 AHDB D1 AHDB D1 AHDB D1 Myzus persicae Clone P most abundant clone at present Bio-insecticides Code Water volume L/ha Timing Untreated AHDB D1 AHDB D1 D7 AHDB D1 D7 AHDB D1 D7 AHDB D1 D7 Spruzit 400 D1 D7 AHDB D1 D7 Majestik 400 D1 D7 AHDB D1 D7 SB Plant Invigorator 400 D1 D7 AHDB D1 D7 AHDB D1 D7 AHDB D1 D7 AHDB D1 D7

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17 Mean number of live aphids Biopesticides - number of live aphids following one spray (first two replicates) Day 1 Day 3 Day 6

18 Biopesticides - number of live aphids following two sprays (first two replicates) N.B. treatments where 100% killed by first spray excluded Mean number of live aphids Day 1 Day 3 Day 6 Day 1 Day 3 Day 6

19 Mean number of live aphids Insecticides - number of live aphids following one spray (first two replicates) Everything that was treated was dead by Day 3 Re-inoculate plants on Day 7 If all killed again then re-inoculate on Day 14 0 Day 1 Day 3

20 Next steps More replicates of peach-potato aphid tests Move onto currant-lettuce aphid, willow-carrot aphid and cabbage aphid Information will be used to design trials for other crop/aphid combinations

21 Thank you to: AHDB Companies supporting SCEPTREplus The SCEPTREplus team Steve Foster, Gaynor Malloch, Brian Fenton Rothamsted Insect Survey The team at Wellesbourne