Résumé:
The potato (Solanum tuberosum L.) is a tuberous herbaceous plant that belongs to the Solanaceae
family. Several biotic and abiotic factors affecting its production include fungi such as mildew. In this
present work, we proposed to evaluate the antagonistic power of Trichoderma viride against parasite
Phytophthora infestans of potato tubers. We conducted two tests; for the first, in confrontation in-vitro,
the direct confrontation was performed on an agar PDA medium to demonstrate the inhibitory capacity
of T. viride on P. infestans. For the second test, in- vivo confrontation, we realized two methods; the
first was carried out using a mycelia disk on the antagonist and the second was done by injecting the
spore solution of T. viride into the potato tubers after this pathogen was applied. The results of the in vitro test revealed that the confrontation between T. viride and the P. infestans showed the inhibitory
capacity of T. viride, be it directly (68%) or remotely (58%) on the growth medium. Interesting results
were also obtained in- vivo. The injection of the tubercles with a T. viride spore solution reduced the
development of P. infestans with an average penetration of 3.28 mm for the T. viride and of 1.65 mm for
the P. infestans. The findings of the mycelia discs method were similar to the injection method with a
penetration average of 2.62 mm for T. viride and 1.81 mm for P. infestans. The test results in -vitro
showed the efficiency of T. viride against P. infestans; while for in-vivo, it was proved that this
antagonist possesses a very significant inhibitory effect that suppresses the spread of the pathogen
