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Aphid transmitted potato Aphid transmitted potato virusesvirusesMaintaining our high health statusMaintaining our high health status

Andy Evans

SAC

Jon Pickup

SASA

Summary

What do you do?

Virus Information

Aphid monitoring

Virus EpidemiologyLeafroll, PVY, PVA

Aphicide Recommendations for Virus Management

Conclusions/Questions

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What do you do?

To trigger the start of your Aphicide Programme do you use:

- a) Potato Council/CSL Water Trap data:

- Your own traps

- Data from the web

- b) Suction Trap data

- c) Advice from an Agronomist

- d) Start on a Fixed Date

- e) Other

What do you do?

Do you take into account Proximity of Virus Sources?

- Virus Levels in Seed - Yes/No

- Proximity of Ware Crops – Yes/No

- Other Sources

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What do you do?

Do you have Aphicide Programmes for Different Varieties?

- Yes/No

Virus Information

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Viruses - Seed Potato Classification

Inspection of crops for visual symptoms of virus infection

Leaf samples from plants showing virus symptoms are sent to SASA Virology Lab

Collation of classification data by SASA SPCS staff

Virus symptoms observed at crop inspection

0%

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1969 1972 1975 1978 1981 1984 1987 1990 1993 1996 1999 2002 2005 2008

Are

a of

see

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xhib

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viru

s sy

mpt

oms

Mosaics Leafroll

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SPCS Laboratory Virus Diagnosis

Most testing is carried out by ELISA

SASA Virology Lab staff test leaf samples received for 10 viruses

SPCS Virus incidence 1999-2008

Potato Leaf Roll Virus14%

Potato Virus YO/C9%

Potato Virus YN (VN)26%Potato Virus A

22%

Potato Virus X11%

Potato Virus S1%

Potato Virus M0%

Potato Virus V4%

Tobacco Rattle Virus4%

Tomato Black Ring Virus

1%

Potato Mop Top Virus8%

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Incidence of non-persistent viruses in the Scottish seed potato crop

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1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

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irus

Potato Virus Y Potato Virus A Potato Virus V

Aphid Information

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Aphids monitored by:

Potato Council/CSL yellow water traps

Aphid suction traps

Presence in the crop

Aphid forecasts

Benefits of Aphid monitoring

Can act as an early warning about aphid activity in local areas

Prompt growers/advisers to monitor individual crops for aphids

Inform on aphicide choice

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Information on aphids

The cumulative appearance of aphids throughout the season can be monitored from the Potato Council network of aphid water traps (http://www.potato.org.uk/aphids) and the UK network of aphid suction traps at the following links:-

http://www.rothamsted.ac.uk/insect-survey/http://www.sasa.gov.uk/seed_potatoes/aphids/bulletins/index.cfm

Potato Council/CSL Water Trap Network

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Peach-Potato aphid on SASA website

Peach-Potato aphid Myzus persicae - Weekly Catches in Scottish Suction Traps

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01-Jun 15-Jun 29-Jun 13-Jul 27-Jul 10-Aug 24-Aug 07-Sep

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05-Oct 19-Oct 02-Nov

Peac

h-Po

tato

aph

ids

1985-2007200620072008

Virus Epidemiology

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Leafroll and Myzus persicae

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1969 1975 1981 1987 1993 1999 2005

Peac

h Po

tato

aph

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Peach Potato aphids Leafroll

Predicting Leafroll

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Leafroll Content - Predicted by virus & Peach-Potato aphids in previous year

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1970-92 Data Model Prediction

Regression Model

PLRV(t) = 0.667PLRV(t+1) + 0.382Mp(t-1) - 2.116

Adjusted r2 = 0.868

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Aphid Monitoring Programme

Level 1: Selected crops in 7 ACAs checked for aphidsLevel 2: All seed crops in ACA checked for aphids

2006

20042002

1994

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19961997

20002001

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2008

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100%

1.00% 10.00% 100.00%

Predicted Leafroll Content

Act

ual L

eafr

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nt

1970-92 Data

Model Prediction

Leafroll management

Mean January/February temperature is critical to Myzus persicae activity in the forthcoming growing season.

Winter temperatures in 2008 were 1.3°C warmer than average.

We predicted that M. persicae would be flying by mid-June and in greater numbers than in an average year.

Control should be targeted against M. persicae (a colonising aphid) and should take place from mid-June.

Varieties susceptible to leafroll include Cabaret, Maris Piper, Russet Burbank, Marfona, Kerr's Pink.

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PVY correlates with cereal aphid catches in the preceding year

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1998 2000 2002 2004 2006 2008

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VY

Rose-Grain aphid Grain aphid Potato Virus Y

PVY can be predicted from cereal aphids and virus incidence in the previous year

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4%

6%

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2% 3% 4% 5% 6% 7% 8% 9%

PVY Content - Predicted by virus & aphids in previous year

Act

ual P

VY C

onte

nt

Regression Model

PVY(t) = 0.85PVY(t-1) + 0.40Ca(t-1) - 3.05

Adjusted r2 = 0.71, p = 0.006

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PVY management

Although other species of aphids can and do transmit PVY in Scotland, virus management should be targeted primarily against transmission by the Rose-Grain and Grain aphids.

Virus management requires the control of non-colonising cereal aphids and may need to take place from late-June.

Varieties susceptible to PVY include King Edward, Harmony, Shepody, Maris Peer, Nicola.

It is difficult to make long term predictions of mid-season cereal aphid activity.

Field transmission of PVA & PVY - 2006

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30-May 13-Jun 27-Jun 11-Jul 25-Jul 08-Aug 22-Aug

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PVA

PVY

Aphid Vector Pressure

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Field transmission of PVA & PVY - 2008

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27-May 10-Jun 24-Jun 08-Jul 22-Jul 05-Aug 19-Aug

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PVA

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Aphid Vector Pressure

PVA Management

What aphid species are transmitting PVA?

Can occur early in the season

Desiree, Russet Burbank, Cabaret, Estima, Hermes and Marfona particularly at risk from PVA

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Aphicide Recommendations

Minimising Virus Risk

Location of the seed crop and proximity to potential sources of virus

- Site seed isolated from ware, veg brassicas, field margins, beetle banks

Roguing, groundkeepers, weeds, dumps, home-saved seed

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Approved Aphicides

-No-fid, Stalwartnicotine

2Teppeki, RouteOne Skiflonicamid

2 (1 on ware)Biscaya*thiacloprid*

3 (2 on ware)Plenum WGpymetrozine

2 (1 on ware)Insyst*acetamiprid*

2 (1 on ware)Actara*thiamethoxam*

-Aphox, Agriguard Pirimicarb, Agrotech Pirimicarb 50 WG, Arena, Barclay Pirimisect, Clayton Pirimicarb 50, Clayton Pirimicarb 50 SG, Cleancrop Miricide, Greencrop Glenroe, Landgold Pirimicarb 50, MilentusPirimicarb, Noble Pirimicarb, Phantom, Pirimate, RouteOne Primro 50 WG, Standon Pirimicarb 50

pirimicarb

4Barbarossa, Clayton Lambada, Clayton Lanark, Clayton Sparta, Clayton Zen, Clean crop Corsair, CleancropSilo, Dalda 5, Hallmark Zeon, Ingot Z, IT Lambda, Lambda C, Landgold Lambda-Z, Markgate 50, RouteOne Lambda C, Warrior

lambda-cyhalothrin

8Dovetail, Clayton Groove, Morticelambda-cyhalothrin + pirimicarb

Max No. of applications

ProductsActive ingredient(s)

Specific recommendations

PVA susceptible cultivars (Desiree, Estima, Golden Wonder, Hermes, Kerr’s Pink, Marfona,Red Pontiac and Russet Burbank) - aphicide treatment from crop emergence. lambda-cyhalothin + pirimicarb mixtures are recommended for the first few treatments as they contain a pyrethroid and a carbamate component. Once potato aphids and peach-potato aphids appear then a tank-mix of lambda-cyhalothrin withpymetrozine, thiacloprid, thiamethoxam, acetamiprid or flonicamid should be used as this will ensure that any aphicide resistant peach-potato aphids will be controlled.

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Specific recommendations (2)

Seed crops that are sited near to vegetablebrassicas, stubble from last seasons vegetablebrassicas, or potato dumps - a tank-mix of lambda-cyhalothrin with pymetrozine, thiacloprid, thiamethoxam, acetamiprid or flonicamid This will ensure that any aphicide resistant peach-potato aphids that may be harboured onthe nearby brassica crops or stubble will becontrolled. The first treatments should begin when aphidsappear.

Specific recommendations (3)

On other seed crops, lambda-cyhalothrin +pirimicarb or tank-mixes of lambda-cyhalothrinwith pymetrozine, thiacloprid, thiamethoxam,acetamiprid or flonicamid should be used assoon as aphids begin to appear. No more than two applications of a neonicotinoid product (thiamethoxam, thiacloprid, acetamiprid) should be applied over a season to an individual crop.

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Starting Your Aphicide Programme

The appearance of aphids in local water traps or suction traps should trigger start of spraying.

Any delay could be costly in terms of virus transmission

Maintaining Your Aphicide Programme

Once spraying has started, maintain 7-10 day spray intervals

Alternate actives mixed with pyrethroid – i.e. don’t stick with pyrethroid-carbamate throughout the programme

Frequency of applications can be reduced later in the season as mature plant resistance will kick in

Late season Nicotine (e.g. No-Fid, Stalwart) can be used with pyrethroid

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Ware crops

Aphid control on ware crops near to seed is recommended – may require a couple of treatments – start when aphids appearOn ware crops isolated from seed, apply aphicides when aphid numbers show a big jump from one occasion to the next – e.g. from 4 per leaf to 12 per leaf. Any aphicide can be applied but resistance problems could occur with pyrethroid and carbamate products

Should you do things differently?

Is the information currently available reliable enough to initiate aphid control?

Do you need to consider the virus risk when implementing an aphid control programme?

Should you use different control programmes for different varieties?

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Should you do things differently?

Is the information currently available reliable enough to initiate aphid control?

Do you need to consider the virus risk when implementing an aphid control programme?

Should you use different control programmes for different varieties?

Should we do things differently?

Do we need more research on virus epidemiology, e.g. PVA?

Should more varieties require post-harvest virus testing prior to classification, i.e. as with Estima?

Anything else?

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Jon Pickup

Head of Virology & Zoology

SASAjon.pickup@sasa.gsi.gov.uk

Andy Evans

Advisory Zoologist

SACAndy.Evans@sac.ac.uk