Blackleg: Reducing its impact in the seed supply chain

Transcription

1 Blackleg: Reducing its impact in the seed supply chain Triona Davey 1, Greig Cahill 1, Monika Krol 1, Karen Fraser 1, Claire Hodge 2 & Gerry Saddler 1 1, SASA & 2, AHDB Potatoes

2 Outline Recent blackleg trends in Scotland Outputs from AHDB Potatoes/Scottish Government Funded Blackleg Research Initial infection and disease development In field spread Geographic clustering Outputs from Pre Basic PB growers blackleg survey Survey aims and business overview Varieties to blame? Current understanding and recommendations

3 Seed area not holding grade From Maureen McCreath, SASA

4 Blackleg by field generation (FG) From Maureen McCreath, SASA

5 Percentage of PB stocks infected by Pectobacterium atrosepticum (Pba) 2013/ /15 PB1 14 (57)* 2 (50) PB2 50 (6) 33 (9) PB3 44 (9) 60 (20) PB4 100 (3) 100 (7) *, Number of crops tested in brackets

6 AHDB Potatoes/SG Funded R&D: Participants Ian Toth, Sonia Humphris & Pete Skelsey James Hutton Institute (Dundee) Gerry Saddler, Greig Cahill & Monika Krol SASA (Edinburgh) Stuart Wale SRUC (Aberdeen) John Elphinstone Fera (York)

7 Diversity of Pba isolates from different sources (2013) Location and seed stock Scotland Farm 2 Variety 1 PB 2 Harvester before lifting Blackleg plants Harvester after lifting Harvested tubers Scotland Farm 2 Variety 2 PB 2 Scotland Farm 2 Variety 3 PB 2 Scotland Farm 3 Variety 4 PB 2 Scotland Farm 4 Variety 5 PB 2 Scotland Farm 5 Variety 6 PB 2 VNTR profiles: From: John Elphinstone, Fera

8 Blackleg progress in PB crops From: Stuart Wale, SRUC

9 Movement of Pba within fields Using experimental plots, track the movement of Pba from infected to healthy plants by monitoring the canopy and below ground during the growing season

10 Experimental field plots Pba can spread from diseased plants in a field to other plants in that field Isolates on plants are found both above and below ground Highest numbers of Pba appear on roots and stems, where they may multiply and infect Even with a heavy inoculum from artificially infected blackleg plants, natural Pba and other Pectobacterium species contaminate plants at increasingly high levels and can cause disease Harvested tubers have both surface (including lenticels) (2/3) and systemic (1/3) contamination Low disease incidence was observed in daughter crop

11 Number of crops vs levels of disease Incidence of blackleg (a c, ) appears to cluster but high levels of disease do not appear to be associated with certain regions crops affected From: Pete Skelsey, JHI

12 Blackleg Survey of PB Growers Location of PB interviewees for AHDB Potatoes Blackleg study Aim: Investigate social changes/industry practices with a view to identifying contributing factors which may be leading to a rise in blackleg, particularly in PB growers. Methodology: One to one interviews based on a series of questions around social, financial and economic change Analysis: In total 30 growers interviewed (28 from Scotland, 1 from Northern Ireland & 1 from England) QDA Miner qualitative data analysis software used to identify key themes

13 Trends in Scottish PB Production

14 What are the main factors driving disease development in crops?

15 Ranking of varieties: blackleg by area Rank Lionheart Premiere Swift Charlotte Charlotte 2 Premiere Maris Bard Fontane Winston Maris Bard 3 Charlotte Winston Premiere Desiree Estima 4 Sagitta Slaney Sylvana Hermes Winston 5 Winston Cara Charlotte Estima Valor 6 Slaney Markies Desiree Cabaret Desiree 7 Markies Hermes Hermes Valor Maris Peer 8 Maris Peer Desiree Estima Cara Cabaret 9 Hermes Estima Maris Peer Maris Piper Hermes 10 Desiree Maris Piper Maris Piper Maris Peer Maris Piper

16 Current understanding The initial (principal?) infection source in PB crops remains elusive There are a number of likely contenders. machinery, adjacent crops (wind & rain), ground water, etc. In Scotland 95% of blackleg cases attributable to Pba. No evidence of new pathogenic groups Once a stock becomes infected seed is the main infection route Environmental conditions amplify the disease effect likely we will always have good and bad blackleg years Some evidence that loss of sulphuric acid has had an impact Could business size be an issue? There is no evidence to suggest that the recent increase is attributable to the current portfolio of varieties

17 Recommendations Hygiene is expensive and time consuming but can reduce/remove some sources of infection Plant/harvest in the dry. Dry down quickly and store under cool conditions Consider separating early generation PB crops from older material Isolation of PB fields may reduce contamination from outside sources (space / polytunnels?) Keep irrigation of all seed crops to a minimum Harvest high grade stocks as early as possible Avoid build up of condensation when bringing material out of store/in transport prior to planting

18 Acknowledgments Fera John Elphinstone JHI Ian Toth, Pete Skelsey & Sonia Humphris SRUC Stuart Wale Funding from AHDB Potatoes and the Scottish Government