Effects of different culture media on the growth and in vitro preservation of Phytophthora infestans

Abstract

Prospecting for Phytophthora infestans, the causative agent of downy mildew, was carried out in the field in six potato-producing localities in the Berkane region and four in the suburbs of Oujda. Samples of potato tubers were also brought from five cold storage rooms. Out of a total of 49 samples collected, including 34 from leaves and 15 from tubers, only 23 isolates were identified, including 22 from leaves and one from tubers. The direct sporocyst passage method was the most reliable and successful compared to other methods. Frozen PP culture medium was used for the isolation and purification of P. infestans. Five culture media (PDA, DFPDT, PP, CMA and NYDA) were used to monitor the various parameters characterizing the fungus, including color, appearance, diameter of mycelial colonies, daily rate of mycelial growth, the survival of the mycelium at 4°C and at 20°C and the rate of sporulation. All these parameters are rather better in the DFPDT, PP and PDA media, average in NYDA and weak in CMA.

Keywords: Phytophthora infestans, potato, culture medium, isolation, Oriental, Moroccontal, Morocco