Independent Variety Trials (IVT)

Blight trialsIn addition to DUS and VCU trials, SASA Variety Testing, in collaboration with its partners Biomathematics and Statistics Scotland (BioSS), James Hutton Limited (JHL) and SAC Consulting Ltd., undertake Independent Variety Trials (IVT) on behalf of the Agriculture and Horticulture Development Board (AHDB). The potato Industry considers it very desirable to compile a comprehensive, independent data set of varietal ratings for diseases considered to be of most importance for UK potato production.  To this end, AHDB Potatoes fund a set of tests for some diseases not covered by the official National List programme but nevertheless fully integrated with the statutory testing system.  A full list of the disease resistances tested can be found on the potato disease testing page.  

 

Agents/breeders of varieties entering the second year of UK National List are invited to enter their varieties for IVT testing.  In addition, agents/breeders of varieties found on the European Union Common Catalogue intended for production in GB are also invited to enter their varieties. The results of all tests are published on the AHDB Potatoes' Potato Variety Database hosted by SASA.

 

Disease Testing

Diseases 

Dry Rot (NL test): (Fusarium coeruleum and F. sulphureum, separate test conducted for each pathogen):  tubers are wounded and inoculated with a suspension of spores and incubated at 12-15oC. The degree of internal rotting is assessed.

Foliage Late Blight (NL test): greenhouse-grown plants at or near flowering are sprayed with a known R-gene complex isolate(s) of Phytophthora infestans.  Leaf area blighted is scored after 7 days incubation.

Foliage Field Late Blight (IVT test):  test plants grown in small field plots are exposed to spores of known R-gene complex isolate(s) from adjacent infected plants of a susceptible variety.  Leaf area blighted is assessed on at least 3 ocassions.

Tuber Late Blight (NL test):  the rose-end of field-grown tubers is sprayed with a known R-gene complex isolate(s) of Phytophthora infestans.  The number of blighted tubers is counted after 10-14 days incubation.

Common Scab (NL test):   tubers are planted in pots containing artificially infested compost and kept dry during tuber initiation. Severity of common scab is assessed on daughter tubers.

Powdery Scab (NL test):  tubers are planted in pots in compost infested with scab peelings and kept wet during tuber initiation.  Severity of powdery scab is assessed on daughter tubers.

Blackleg (NL test):   tubers are inoculated at heel end with Pectobacterium atrosepticum and planted in an irrigated field trial. The incidence of blackleg is assessed at least 3 times during the growing season.

Black Dot (IVT test):  tubers are planted in a greenhouse in pots filled with a compost infested with mycelia and spores of Colletotrichum coccodes.  The severity of black dot is assessed on daughter tubers after 6 weeks incubation.

Black Scurf (IVT test):  tubers are planted in a greenhouse in pots filled with a compost infested with mycelia of at least 3 isolates of Rhizoctonia solani.  The severity of black scurf is assessed on daughter tubers.

Silver Scurf (IVT test):  tubers are planted in artificially infested compost of Helminthosporium solani and planted in a polytunnel.  The severity of silver scurf is assessed on daughter tubers after 4-5 months incubation at 12-15oC.

Skin Spot (IVT test):  tubers are dipped in a suspension of spores and mycelia of Polyscytalum pustulans and planted outdoors in compost in pots.  The  severity of skin spot is assessed on daughter tubers after 5-6 months incubation at 5-8oC.

Pests

Potato Cyst Nematode (Globodera spp.) (NL test, Separate tests are conducted for G.rostochiensis pathotype Ro1 and G.pallida pathotypes 2/3 and 1):  tubers are planted in pots in  compost infested with a standard concentration of PCN eggs.  Cyst multiplication on roots is assessed. View

Damage

Damage, external (splitting) and internal (bruising) (NL test):  a standard force is applied to the heel end of field grown tubers.  Tubers for ‘splitting’ test are stored at 4-6oC and the incidence of splitting at the point of impact is recorded. Tubers for ‘bruising’ test are stored at 9-11oC and the depth of damage at point of impact measured.

Tuber Quality

External tuber defects:  The weight of tubers >35 mm and < 35 mm is recorded in kg, unmarketable tubers are divided into 10 categories: growth cracks, greens, mis-shapes,mechanical damage, cutworms, common scab >25% surface area covered, late blight, wet rots and other faults. The weight of each category is recorded in kg.

Internal tuber defects:  The number of tubers with hollow heart, internal blemishes or other defects is recorded by cutting, initially, 25 tubers. If any faults are found in this sample, a further 25 tubers are cut.

View the official Value for Cultivation and Use (VCU) protocols and procedures documents on the Gov.uk website.

New Varieties

Disease, pest and damage susceptibility ratings obtained during National List Trials for new varieties are available on the AHDB Potatoes' Potato Variety Database together with results from Independent Variety Trial tests. Additional information on these varieties may also be found on the European Cultivated Potato Database.

Varieties added to the UK National List in 2015

Sorrento
Golden Beauty
Golden Sun 
Jubilee 
Libertie 

Varieties added to the UK National List in 2016

Cammeo 
Raleigh 
Mayan Rose
Scapa 
Reiver 

Varieties added to the UK National List in 2017

FL2339
Radebe
Elland
Charlton
Tribute