A method for the artificial inoculation of potato tubers with Phytophthorainfestans and polymerase chain reaction assay of latently infected sproutsand stems

This article contains a detailed description of a reliable method for the i noculation of potato tubers with Phytophthora infestans. This technique was developed as a general basic method for greenhouse and field trials to stu dy the development of the primary inoculum source in potato crops. It was a pplied to increase the reproducibility of infections from tubers to sprouts . Afterwards the pathogen was detected in light sprouts and stems at differ ent stadiums of plant growth by the polymerase chain reaction-based test (P CR). From this it follows that Phytophthora infestans is able to grow direc tly up into the stem from the tuber as mycelium. In the course of plant gro wth the concentration of mycelium fell below the detection limit in some of the assayed stems on account of dilution effects, although the symptoms oc curred in the following period. Apparently the pathogen is also able to cau se symptoms in the plant at very low concentrations.