Poster Presentation Science Protecting Plant Health 2017

Ascochyta blight pathogens isolated from Australian native and weed legumes (#220)

Elizabeth C Keirnan 1 , Matthew H Laurence 2 , Jenny A Davidson 3 , Brett A Summerell 2 , Edward C.Y Liew 2 , Eileen S Scott 1
  1. The University of Adelaide, Glen Osmond, SA, 5064, Australia
  2. The Royal Botanic Gardens and Domain Trust, Mrs Macquaries Rd, Sydney, NSW, 2000, Australia
  3. South Australian Research and Development Institute, Adelaide, SA, 5001, Australia

In Australia, ascochyta blight (blackspot) complex is the most common and damaging disease of field pea (Pisum sativum L.), causing yield losses ranging from 15 to 75%.  Internationally, four fungal species are responsible for ascochyta blight of field pea; Didymella pinodes (syn. Peyronellea pinodes), Phoma medicaginis var. pinodella, Ascochyta pisi and Phoma koolunga. P. koolunga (previously identified as Macrophomina phaseolina) was found on field peas with ascochyta blight in South Australia in the early 1980s.

A survey of fungal species associated with foliar disease of native, pasture and weed legumes is in progress, with the aim of understanding the origin(s) and host range of Phoma koolunga. This survey may also provide information on the role and extent to which volunteer plants in cultivated or non-cultivated ecosystems are a source of pathogens in the ascochyta blight complex in Australia. 

For four isolates found to date, infectivity on field pea, cv. Kaspa, was tested by spray-inoculation in a controlled environment growth room. Field pea plants treated with P. koolunga and sterile water served as positive and negative controls respectively.

The results revealed isolates of Didymella pinodes and Ascochyta viciae/A. pisi from a native Senna species, Vicia cracca (bird vetch), Lathyrus tingitanus (tangier pea) and Vicia sativa (common vetch) infected and caused typical ascochyta blight lesions on field pea. The implications of these findings are discussed.