| Abstrakt: |
Isolates of Hypornyces (Fusarium) solani f. pisi collected in South Australia, when single-spored and cultured under the same conditions, were separable into three distinct clones. Pairings of the three clones (SA-1, 2, and 3), and of a fourth collected in New South Wales (NSW-I), with tester clones of known mating type and sex, showed that SA-1 and SA-2 were of one mating type (+), while SA-3 and NSW-1 were of another mating type (–). SA-1 and NSW-1 were hermaphrodites; SA-2 and SA-3 functioned only as males. When SA-1 and NSW-1 were paired in reciprocal crosses, fertile perithecia developed in both cases. Fertile perithecia also developed when SA-2 and SA-3 were used as males to fertilize NSW-1 and SA-1 respectively. A clone of H. solani f. pisi, identical with SA-1 in pathogenicity, cultural appearance, sex, and mating type, was recovered from wind-blown soil in a virgin area approximately 1 mile from a pea field but not from soil taken from districts some distance (30 miles in one case and 200 miles in another) from pea-growing districts. Other isolates identical with SA-1 in cultural appearance, mating type, sex, and pathogenicity were recovered from dust taken from a bag of non-treated, certified New Zealand pea seed imported into South Australia, from field soil collected in pea seed-producing areas of the Pacific North-west of the United States, and from England. The occurrence of compatible clones on different continents appears to be due to an international movement of the fungus on pea seed. |
