R. Jonsson et al., VIRULENCE STUDIES OF SWEDISH NET BLOTCH ISOLATES (DRECHSLERA-TERES) AND IDENTIFICATION OF RESISTANT BARLEY LINES, Euphytica, 94(2), 1997, pp. 209-218
Six Swedish and one Canadian single spore isolate of Drechslera teres
f. teres were used to screen 109 barley lines for disease resistance a
nd to select a differential set of barley lines for use in assessing p
athogen virulence. A large variation for net blotch resistance was fou
nd among the 109 barley lines which were classified into four groups,
those showing: 1) only resistant reactions; 2) differential reactions;
3) only intermediate reactions and 4) only susceptible reactions. The
European commercial varieties included, showed susceptibility to all
Swedish isolates, but a few were resistant to the Canadian isolate. Th
e 18- member differential set separated 25 Swedish and two Canadian is
olates of D. teres into 14 pathotypes, three of which made up 59% of t
he isolates. Only one barley differential (CI 9776) was resistant to a
ll net form isolates. Host selection on the pathogen seems to be prese
nt as all six isolates obtained from cv. Golf belonged to the same pat
hotype and 4 of 5 isolates from cv. Karin shared the same virulence pa
ttern. The net form of net blotch (D. teres f. teres) predominated in
the sampled regions and only one of 26 Swedish isolates was of the spo
t form (D. teres f. maculata).