Susceptibility of potato cultivars to powdery scab (caused by Spongospora subterranea)

Transcription

1 Federal Department of Economic Affairs, Education and Research EAER Agroscope Susceptibility of potato cultivars to powdery scab (caused by Spongospora subterranea), Jean-Marie Torche, Theo Ballmer, Thomas Hebeisen I good food, healthy environment

2 Material and method Total number of field trials: 50 Locations: La Fretaz (Bullet, VD) 1 202m a.s.l. Wallestalden (Langnau, BE) 950m a.s.l Reckenholz (Zürich, ZH) 443m a.s.l Years: 2004 to 2015 Cultivars: 212 cultivars tested Cv. Agria, Bintje, Lady Felicia and Lady Claire were used as controls Sampling at harvest Nb. of tubers: 100/variety and trial 2

3 M&M: locations of trials Reckenholz La Frêtaz Wallestalden 3

4 M&M: observations Percentage of tubers with scabs Assessment of the scabs on the tubers 0 = non tumors 1 = 1 or 2 tumors 2 = 3-10 tumors 3 = >10 tumors 4 = >many tumors Calculation of the tubers infection index:. Powdery scab workshop Einsiedeln: 17th July-20th July

5 M&M: selection of trials Tuber symptoms observed out of 50 field trials Rejection of the trials in which: No tubers of Bintje are showing symptoms and/or No tubers of Lady Claire are showing symptoms Rejection of control varieties presenting aberrant results (visual observation of the linerar regression) 5

6 M&M: resistance of the control cv. Classification following a 9 grades scale of resistance: very low (9); very low to low (8); low (7); low to medium (6); medium (5); medium to high (4); high (3); high to very high (2); very high (1) Calculation of the resistance of all control cultivars using the equation of the linear regression of the extreme values of symptoms expression (average of the maximum for all trials) Observation Minimum Maximum Percentage of infected tubers 0% 69% Index

7 M&M: resistance of the control cv. The exemple of cv. Agria: cv. Agria cv. Agria 7

8 M&M: resistance of the control cv. Cultivar Observation Average values Resistance scale Agria Index % Bintje Index % Lady Felicia Index % Lady Claire Index % Maximum Index %

9 M&M: resistance of the tested cv. Step 1: for each trial, use of the linear regression between the resistance scale and the symptoms expression (index and %) of the control cultivars Exemple: trial in the location Reckenholz in the year

10 M&M: resistance of the tested cv. Step 2: Calculation of the resistance of a tested cultivars (for example the cv. Georgina) For this trial: ( )/2 = 4.03 For all trials (n=3): mean value of all trials ( )/3=

11 Results: loss of trials 29 trials (58%) were loss due to low disease pressure The risk of trial loss varies depending on the location: 22% of loss for Wallestalden (2 out of 9 trials) 39% of loss for La Frêtaz (7 out of 18 trials) 87% of loss for Reckenholz (20 out of 23 trials) 11

12 Results: high variability High variability of response from one trial to the other A cultivar has to be tested several years Only the cultivars tested for at least two years were considered (116 out of 212) 12

13 Results: distribution of resistance Very low resistance: 0.9% of the cultivars (n=1) Very low to low resistance: 0.9% of the cultivars (n=1) Low resistance: 3.4% of the cultivars (n=4) Low to medium resistance: 5.2% of the cultivars (n=6) Medium resistance: 8.6% of the cultivars (n=10) Medium to high resistance: 12.1% of the cultivars (n=14) High resistance: 21.6% of the cultivars (n=25) High to very high resistance: 20.7% of the cultivars (n=24) Very high resistance: 25.9% of the cultivars (n=30) Mean of all cultivars: high resistance (n=116) 13

14 Results by class Very low Low to medium Medium Allians (n=3) Agnes (n=2) Caruso (n=2) Clairette (n=3) Crisper (n=3) Very low to low Fabiana (n=3) Dolce Vita (n=3) Amany (n=3) Merida (n=2) Doris (n=2) Oriana (n=2) Erntestolz (n=3) Low Rosa Gold (n=2) Mustang (n=3) Agria (n=21) Novella (n=3) Eurostar (n=3) Pepite (n=2) Georgina (n=3) Printaline (n=2) Sonate (n=3) Talent (n=2) 14

15 Results by class Medium to high Antoinet (n=3) Opaline (n=3) Bintje (n=20) Pirol (n=3) Challenger (n=3) Pomqueen (n=3) Crispy (n=3) Toscana (n=3) Elfe (n=3) Grandeur (n=2) Lady Claire (n=18) Mozart (n=3) Musica (n=3) Naviga (n=3) 15

16 Results by class High Albata (n=3) Esmeralda (n=3) Puccini (n=3) Apolline (n=3) Forza (n=3) Red Fantasy (n=2) Arietis (n=2) Granada (n=3) Roncalla (n=3) Ballerina (n=3) Gwenne (n=2) Salome (n=2) Canelle (n=3) Kiebitz (n=3) Umatilla Russet (n=3) Clarina (n=3) Krone (n=2) Corsa (n=3) Lanorma (n=2) Delianne (n=3) Maria Sarah (n=3) Dinky (n=3) Omega (n=3) Erika (n=2) Ottawa (n=3) 16

17 Results by class High to very high Alert (n=2) Fabiola (n=3) Soraya (n=2) Anoe (n=3) Fridor (n=3) Toluca (n=4) Antonia (n=2) Gala (n=2) Venezia (n=2) Anuschka (n=3) Lady Felicia (n=18) Vivi (n=3) Biogold (n=3) Lady Lenora (n=3) Bridget (n=3) Lady Valora (n=2) Citadelle (n=3) Lolita (n=3) Colomba (n=3) Lucie (n=3) Daniela (n=3) Magnum (n=2) Destiny (n=2) Rumba (n=3) 17

18 Results by class Very high Action (n=3) Kiwi (n=3) Red Lady (n=3) Ambrine (n=2) Lady Amarilla (n=3) Red Scarlett (n=2) Cecile (n=3) Lady Blanca (n=2) Rodriga (n=3) Celtiane (n=3) Leontine (n=3) Romanze (n=2) Diego (n=3) Malou (n=2) Satellite (n=3) Endeavour (n=2) Mariska (n=2) Sirtema (n=3) Galante (n=2) Miss Malina (n=3) Sissi (n=2) Golf (n=3) Pandora (n=2) Susanne (n=3) Gourmetta (n=3) Performer (n=2) Taurus (n=3) Gredine (n=3) Poupette (n=2) Triplo (n=2) 18

19 Conclusions The soil of the locations used for variety trials has to be highly infected by the pathogen in order the minimize the risk of trial loss Not all the years of trial can be used to asses the susceptibility of the cultivars, a minimum of disease pressure is needed The variability of response is high among trials, thus the trials needs to be repeated several times (years) A minimum of 3 to 4 control cultivars are needed to have reliable results New cultivars are overall tolerant to the disease 19

20 Acknowledgments Roger Wütrich Christian Vetterli Walter Herren and many others 20

21 Thank you for your attention Agroscope good food, healthy environment 21