Utilising certified seed is an important principle in providing a potato crop with the greatest opportunity to grow to its full potential free of disease. Within Australia economically important tuber blemish diseases affecting potato tuber quality include Black scurf, Common scab, Powdery scab and Root knot nematode, caused by infections with the pathogens, Rhizoctonia solani, Streptomyces scabies, Spongospora subterranea f. sp. subterranea, and Meloidogyne spp. respectively. All of these pathogens may be carried on seed-tubers providing inoculum for disease in the subsequent crops, and are assessed in potato seed-tuber certification schemes world-wide. Typically seedlots are certified by visual subjective assessments of disease but recently developed quantitative polymerase chain reaction (qPCR) tools that detect and enumerate pathogen DNA provide an additional measure of seed tuber health. We compared both visual and qPCR assessments of potato seedlots passing through the Tasmanian potato certification scheme over a three year period. Further, selected tubers carrying tuber-borne inoculum loads of the three pathogens were grown in pathogen-free potting soil to establish whether the concentration of pathogen DNA from the tuber peel was associated with progeny crop disease. Outcomes suggest that visual assessment, in most circumstances provides an accurate measure of tuber seed health for certification; however qPCR was able to clearly differentiate difficult to distinguish diseases and identify levels of pathogen DNA present on symptomless tubers. Additionally, it was shown that planting tubers with high pathogen inoculum loads led to enhanced progeny disease compared to planting 'certified' tubers.
Funding
Horticulture Innovation Australia
History
Publication title
Acta Horticulturae
Volume
1118
Editors
JR Schultheis
Pagination
117-123
ISSN
0567-7572
Department/School
Tasmanian Institute of Agriculture (TIA)
Publisher
International Society for Horticultural Science
Place of publication
Belgium
Event title
XXIX International Horticultural Congress on Horticulture: Sustaining Lives, Livelihoods and Landscapes: International Symposium on Root and Tuber Crops: Sustaining Lives and Livelihoods into the Future
Event Venue
Brisbane, Australia
Date of Event (Start Date)
2014-08-17
Date of Event (End Date)
2014-08-22
Rights statement
Copyright 2016 The International Society for Horticultural Science