A. Purwantara et al., VARIATION IN PATHOGENICITY AND VIRULENCE OF PHYTOPHTHORA-CLANDESTINA ON 4 CULTIVARS OF SUBTERRANEAN CLOVER, Australian journal of experimental agriculture, 35(6), 1995, pp. 717-724
The pathogenicity of 6 isolates of Phytophthora clandestina on seedlin
gs of 4 cultivars of subterranean clover was studied. There was a high
ly significant isolate x cultivar interaction in pathogenicity tests o
n axenic seedlings and seedlings grown in pasteurised potting mix or u
ntreated sandy loam soil, indicating the existence of race-cultivar sp
ecificity. The isolates showed differences in virulence against the cu
ltivars. Three isolates (race 0) caused severe disease only on Woogene
llup; 2 isolates (race 1) caused severe disease on Larisa, Trikkala, a
nd Woogenellup, but not on Meteora; one isolate (race 2) caused severe
disease on Meteora and Woogenellup, but not on Larisa and Trikkala. A
s well as differing in virulence (the ability of a race to attack a ra
nge of cultivars), the races also differed in their aggressiveness on
Woogenellup, with race 2 being the most, and race 0 the least, pathoge
nic. The isolates varied in their growth rate on agar medium, but this
was not related to virulence or aggressiveness.