Evaluation location: Andalucía, Spain
Pisum spp. was screened for rust resistance under field conditions at Cordoba, Spain, during the season 2002-2003. Each accession was represented by a 1.5 m long single row that was 0.7 mapart, with 25 plants per row. The first 50 cm of each test row were sown with the susceptible pea cv. Messire to serve both as a control and spreader of the disease. The plot was inoculated twice from mid-March, at 2-week intervals, to ensure high and uniform levels of rust infection. Inoculation consisted of spraying an aqueous suspension of urediospores from a single pustule isolate Up-Co01 of U. pisi collected at Co' rdoba. The urediospores were suspended in tap water (6 x 10 fourth spores mL -1), to which Tween-20 (0.03%, v/v) was added as a wetting agent.
When rust development started uring 2004-2005 season, disease severity was assessed at 2-week intervals by a visual estimation of the leaf area covered with rust pustules (%). These data were used to calculate the area under the disease progress curve (AUDPC), using the following formula in the Field Crops Research 114(2009) 198-203 article.
The susceptible control cultivar Messire had a AUDPC of 1062.5 and 45% leaf area covered with pustules.