Impact of powdery scab (Spongospora subterranea) on the Swiss potato seed production

Size: px

Start display at page:

Download "Impact of powdery scab (Spongospora subterranea) on the Swiss potato seed production"

Victoria Pearson
5 years ago
Views:

1 Federal Department of Economic Affairs FDEA Agroscope Changins-Wädenswil Research Station ACW Impact of powdery scab (Spongospora subterranea) on the Swiss potato seed production Brice Dupuis, Henri Gilliand, Werner Wild 11 July 211

2 Seed potato production in Switzerland NL: 35 ha D : 18 ha F : 15 ha CH: 1 5 ha No selection in Switzerland 11 July 211 Potato seed demand: 25 T / year Import: 2-3 T / year 2

3 Swiss potato seed production actors 6 cooperatives of growers OSP & VSO SEMAG SGD ASS 7 visitors 11 July 211 3

4 Standards Standard for certified seed (%) Control CH EU UNECE Quaranteen diseases Crop Pectobacterium/Dickeya Crop 1 4 1,5 PVY Crop,2 1 1 Lot Powdery scab Lot Rhizoctonia Lot No standard for Powdery scab in Switzerland 11 July 211 4

5 Control of external defects Objectives Early information on seed lot quality concerning infections by Rhizoctonia and Scabs (Spongospora and Streptomyces) Decision support system to eliminate the too infected lots (non-binding test) Duration and size of the sample (5239 lots): 26 : 75 lots of Agata, Agria, Charlotte, Innovator and Lady Claire 27 : 1164 lots all varieties 28 : 1153 lots all varieties 29 : 194 lots all varieties 21 : 178 lots all varieties All Swiss potato seed production 11 July 211 5

6 Material and method Sampling procedure Sampling of 1 to 45 tubers in the field for virus testing (ELISA), part of the certification process Subsample of 1 tubers Washing of the subsample Observation of the subsample Restitution of the subsample to the whole sample for virus testing (ELISA) Observations Number of infected tubers Severity of the attacks 11 July 211 6

7 Rhizoctonia solani Scales Spongospora subterranea Note 1 Note 3-5 Note 7 Note 9 Streptomyces sp.: Superficial common scab Deep pitted common scab 11 July 211 Score 1-3 Score 5 Score 7 Score 9 7

8 Identification of the pathogen: AgriStrip of Bioreba 11 July 211 8

9 Results: disease pressure index and percentage of infected tubers Disease pressure index= (score*nb. tubers) 3 Infecte ed tubers (%) R² = Disease pressure index Good correlation between disease pressure index and percentage of infected tubers 11 July 211 9

10 Results: relative importance of the diseases ulative rainfall (mm) Infected tubers (%) Cum Rhizoctonia (sclerotia) Deep pitted common scab Cumulative rainfall Powdery Scab Superficial common scab Rhizoctonia (sclerotia) Common Powdery scabsscab and RhizoctoniaDeep are pitted the common major problems scab Up to 1,7% Superficial of infected common tubers scab by Average powdery temperature scab in Inf. tub bers (%) & Temp. ( C) 11 July 211 1

11 Results: cultivar susceptibility Number of samples Infected tubers (%) 11 July Lady Rosetta Lady Felicia Innovator Ditta Désirée Charlotte Victoria Nicola Bintje Fontane Agata Markies Lady Claire Agria Lady Christl Susceptible varieties: Lady Christl Agria Lady Claire Markies Less susceptible varieties: Lady Rosetta Lady Felicia Innovator Ditta Désirée

12 Results: impact of the generation R² = Infe ected tubers (%) Num mber of samples F4 S SE1 SE2 SE3 E The generation of the mother seed lot seems to have an influence on the symptoms observed on the progeny tubers 11 July

13 Results: influence of rainfall of the year Infected tubers (%) R² =.3241 Infected tubers (%) Cumulative rainfall (mm) Cumulative rainfall Infected tubers (%) Cumulative rainfall Low correlation between rainfall (April-August) in the area and the status of the Spongospora prevalence for each year and each area Infected tubers (%): R 2 =,3241 Disease pressure index: R 2 =,3621 Atypical situation in 26 (maybe due to the bias induced by the choice of the weather stations) 11 July

14 Infected tubers (%) Infected tubers (%) 1.2 Results: influence of the location 25 SGD and SEM seems to be more infected No clear relation with the cultivated varieties, rainfall 1219and temperature production 5.2 in associated with ware In SGD and SEM area, seed potato potato production OSP & SVO ASS SGD SEM Number of samples Infected tubers (%) OSP & SVO ASS SGD SEM Cumulative rainfall (mm) Infected tubers (%) % susc. var. Mean temperature ( C) OSP & SVO ASS SGD SEM OSP & SVO ASS SGD SEM July

15 Results: Infection outbreaks 6 cooperatives of growers OSP & VSO ASS SGD SEMAG 11 July 211 Outbreaks are spread in the production areas No clearly identified healthy areas 15

16 Federal Department of Economic Affairs FDEA Agroscope Changins-Wädenswil Research Station ACW Thank you for your attention

Summary of the session on national potato production and the powdery scab situation

Summary of the session on national potato production and the powdery scab situation S. Wale, SAC, Ferguson Building, Craibstone Estate, Bucksburn, Aberdeen AB21 9YA, UK Although powdery scab is favoured