Potato tubers cv. Bintje were washed, disinfected for
5 min in a 5% sodium hypochlorite solution, thoroughly
washed with water and left to sprout. After sprouting
60 tubers were planted in pots (9 cm diam.) filled
with sterilised river sand and kept in a growth chamber
where the temperature was recorded every hour using
a data logger (Testo 175-T1; Testo) during the time
of the experiment. Three weeks after planting, when
roots had developed, each pot was inoculated with 500
freshly hatched J2 (