Mg. Cromey et Slh. Viljanenrollinson, VIRULENCE OF PUCCINIA-HORDEI ON BARLEY IN NEW-ZEALAND FROM 1990 TO 1993, New Zealand journal of crop and horticultural science, 23(2), 1995, pp. 115-119
Leaf rust of barley (Hordeum vulgare L.), caused by Puccinia hordei Ot
th. is common in New Zealand. It is particularly prevalent in the Cant
erbury region of the South Island. In a virulence survey carried out b
etween 1990 and 1993 to determine the extent of pathogenic variation i
n the population of P. hordei in New Zealand, four virulence patterns
were detected amongst 187 isolates from barley. All isolates were viru
lent on the genes Pa, Pa-2, Pa-4, Pa-6, Pa-9, and Pa-12, and avirulent
on Pa-7. Eighteen, 10, and 99% of isolates were virulent on the genes
Pa-3, Pa-5, and Pa-8 respectively. No isolates were virulent on the c
ombination of Pa-3 and Pa-5. It is postulated that the barley cultivar
'Liberty' relies on the gene Pa-3 for its resistance to leaf rust. Th
is is the first record of virulence on Pa-3 and Pa-12 in New Zealand.
The cultivars 'Liberty' and 'Triumph' (which contains Pa-12) provided
selection pressure for the spread of pathotypes with these two virulen
ces respectively.