CFI is suitable for recognition of downy-mildew-infected leaf
discs of butterhead and batavia lettuce cultivars/lines. For identification
of downy mildew susceptible cultivars by CFI, the time from
dai 10 to 14 was suitable. In plants of susceptible cultivars successful
infection let to a significant decrease of Fv/Fm of up to 0.35 relative
units. In infected leaf discs of resistant cultivars, means of Fv/
Fm per Petri dish declined by only 0.1 at maximum until dai 14.