Occurrence of species of Aspergillus and Penicillium in roots of wheat and ryegrass and their effect on root rot caused by Gaeumannomyces graminis var. tritici [Lolium rigidum; Triticum aestivum]
1988
Dewan, M.M. | Sivasithamparam, K. (Western Australia Univ., Nedlands (Australia). School of Agriculture)
Frequency of occurrence of species of Aspergillus and Penicillium were higher in roots subjected to washing only and plated onto PDA or PDA amended with lactic acid. In general, species of these two genera were common at the stem extension stage. P.nigricans, P.janthinellum, P.griseofulvum, P.fuscum, Eupenicillium sp. and P.turbatum were isolated at a higher frequency than other species. When introduced at 1 percent inoculum level A.terreus, P.fuscum, P.griseofulvum and P.nigricans caused severe damage to wheat and ryegrass seedlings. When these isolates were screened for antagonism towards Gaeumannomyces graminis var. tritici (Ggt) on agar the strongest antagonism was shown by P.griseofulvum, A.terreus, P.nigricans, P.fuscum and P.janthinellum. The presence of A.terreus, P.griseofulvum or P.fuscum with Ggt decreased root rot of wheat and ryegrass caused by Ggt in sterilised and non-sterilised soil, while P.nigricans showed a similar effect in non-sterilised soil only. However, none of the isolates tested would be suitable as biological control agents.
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