Aphid transmitted potato viruses

Transcription

1 Aphid transmitted potato viruses Maintaining our high health status Jon Pickup SASA Andy Evans SAC Summary What do you do? Virus Information Aphid monitoring Virus Epidemiology Leafroll, PVY, PVA Aphicide Recommendations for Virus Management Conclusions/Questions 1

2 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 2

3 What do you do? Do you have Aphicide Programmes for Different Varieties? - Yes/No Virus Information 3

4 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 Area of seed crop exhibiting virus symptoms 80% 70% 60% Mosaics Leafroll 50% 40% 30% 20% 10% 0%

5 SPCS Laboratory Virus Diagnosis SASA Virology Lab staff test leaf samples received for 10 viruses Most testing is carried out by ELISA SPCS Virus incidence Tobacco Rattle Virus 4% Tomato Black Ring Virus 1% Potato Virus X 11% Potato Virus S 1% Potato Virus M 0% Potato Virus V 4% Potato Mop Top Virus 8% Potato Leaf Roll Virus 14% Potato Virus YO/C 9% Potato Virus A 22% Potato Virus YN (VN) 26% 5

6 Incidence of non-persistent viruses in the Scottish seed potato crop Crops with virus 10% 9% 8% 7% 6% 5% 4% 3% 2% 1% 0% Potato Virus Y Potato Virus A Potato Virus V Aphid Information 6

7 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 7

8 Information on aphids The cumulative appearance of aphids throughout the season can be monitored from the Potato Council network of aphid water traps ( and the UK network of aphid suction traps at the following links:- tins/index.cfm Potato Council/CSL Water Trap Network 8

9 Peach-Potato aphid on SASA website Peach-Potato aphids Peach-Potato aphid Myzus persicae - Weekly Catches in Scottish Suction Traps Apr 04- May 18- May 01-Jun 15-Jun 29-Jun 13-Jul 27-Jul 10-Aug 24-Aug 07- Sep 21- Sep 05-Oct 19-Oct 02-Nov Virus Epidemiology 9

10 Leafroll and Myzus persicae Peach Potato aphids % 70% 60% 50% 40% 30% 20% 10% 0% Crops with Leafroll Peach Potato aphids Leafroll Predicting Leafroll 100% Data Model Prediction Actual Leafroll Content 10% 1% Regression Model PLRV(t) = 0.667PLRV(t+1) Mp(t-1) Adjusted r2 = % 1% 10% 100% Leafroll Content - Predicted by virus & Peach-Potato aphids in previous year 10

11 Aphid Monitoring Programme 100% Level 1: Selected crops in 7 ACAs checked for aphids Level 2: All seed crops in ACA checked for aphids Actual Leafroll Content 10% 1% Data Model Prediction 0% 1.00% 10.00% % Predicted Leafroll Content 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. 11

12 PVY correlates with cereal aphid catches in the preceding year Mean Scottish suction trap catch Rose-Grain aphid Grain aphid Potato Virus Y 10% 8% 6% 4% 2% 0% Crops with PVY PVY can be predicted from cereal aphids and virus incidence in the previous year Actual PVY Content 10% 8% 6% 4% 2% Regression Model PVY(t) = 0.85PVY(t-1) Ca(t-1) Adjusted r2 = 0.71, p = % 2% 3% 4% 5% 6% 7% 8% 9% PVY Content - Predicted by virus & aphids in previous year 12

13 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 noncolonising 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 midseason cereal aphid activity. Field transmission of PVA & PVY Aphid Vector Pressure PVA PVY Aphid Vector Pressure 70% 60% 50% 40% 30% 20% 10% Virus transmission 0 30-May 13-Jun 27-Jun 11-Jul 25-Jul 08-Aug 22-Aug 0% 13

14 Field transmission of PVA & PVY Aphid Vector Pressure PVA PVY Aphid Vector Pressure 70% 60% 50% 40% 30% 20% 10% Virus transmission 0 0% 27-May 10-Jun 24-Jun 08-Jul 22-Jul 05-Aug 19-Aug 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 14

15 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, homesaved seed 15

16 Approved Aphicides Active ingredient(s) Products Max No. of applications lambda-cyhalothrin + pirimicarb lambda-cyhalothrin pirimicarb thiamethoxam* acetamiprid* pymetrozine thiacloprid* flonicamid nicotine Dovetail, Clayton Groove, Mortice Barbarossa, Clayton Lambada, Clayton Lanark, Clayton Sparta, Clayton Zen, Clean crop Corsair, Cleancrop Silo, Dalda 5, Hallmark Zeon, Ingot Z, IT Lambda, Lambda C, Landgold Lambda-Z, Markgate 50, RouteOne Lambda C, Warrior Aphox, Agriguard Pirimicarb, Agrotech Pirimicarb 50 WG, Arena, Barclay Pirimisect, Clayton Pirimicarb 50, Clayton Pirimicarb 50 SG, Cleancrop Miricide, Greencrop Glenroe, Landgold Pirimicarb 50, Milentus Pirimicarb, Noble Pirimicarb, Phantom, Pirimate, RouteOne Primro 50 WG, Standon Pirimicarb 50 Actara* Insyst* Plenum WG Biscaya* Teppeki, RouteOne Ski No-fid, Stalwart (1 on ware) 2 (1 on ware) 3 (2 on ware) 2 (1 on ware) 2 - 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 with pymetrozine, thiacloprid, thiamethoxam, acetamiprid or flonicamid should be used as this will ensure that any aphicide resistant peachpotato aphids will be controlled. 16

17 Specific recommendations (2) Seed crops that are sited near to vegetable brassicas, stubble from last seasons vegetable brassicas, 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 on the nearby brassica crops or stubble will be controlled. The first treatments should begin when aphids appear. Specific recommendations (3) On other seed crops, lambda-cyhalothrin + pirimicarb or tank-mixes of lambda-cyhalothrin with pymetrozine, thiacloprid, thiamethoxam, acetamiprid or flonicamid should be used as soon 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. 17

18 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 18

19 Ware crops Aphid control on ware crops near to seed is recommended may require a couple of treatments start when aphids appear On 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? 19

20 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? 20

21 Jon Pickup Head of Virology & Zoology SASA Andy Evans Advisory Zoologist SAC 21