*2.4. Monitoring of Potato Blight*

The experimental plots were set up in a randomized block design in 4 replications. Chemical protection against the plague was not carried out during the growing season of potato. Observations on each cultivar were carried out from the moment of potato emergence, every 10 days until the disease appeared on all cultivars. The time when 25% of the plants are already in the field was assumed as the date of potato emergence. In the period of greater risks of plague (prolonged rainfall or fog), observations were carried out more often (1–2 times a week).

The severity of the plague attack was rated on a scale of 9◦, where 9◦ means single necrotic spots and the destruction of the assimilation surface up to 0.5%, and 1◦ means the complete destruction of the plant. The above data, together with the degree of plant development at the time of observation (according to the BBCH scale), were uploaded to the server thanks to the Pi-monitoring program. Additional information on the location and soil type of the field, cultivated variety and date of emergence of the plants was also entered into the database. After the end of the growing season, the rate of spread of potato blight was determined and calculated as the increase in the damage to tops per unit of time according to van der Plank [26].
