Table 1.

Example of the assessment of durability of the fire blight (FB) control measure investigated.

Durability of FB Control Measure
Effect	Negligible				Low				High				Very High
Development of resistance in Erwinia following intensive use of the product	No resistance or tolerance development				Less than 10% of the strains would develop resistance or tolerance to the product after more than 20 years				More than 50% of the strains become resistant in 10–20 years				All FB strains become resistant in the next 5 to 10 years
Probability of damage occurrence a	1	2	3	4	1	2	3	4	1	2	3	4	1	2	3	4

^a: Probability scale used: (1) damage possible, but under comparable conditions has never occurred (=highly unlikely); (2) damage possible in individual cases under particularly unfavorable conditions; (3) damage under comparable conditions already known (occurrence in 10%–50% of the cases); (4) occurrence of damage frequent (>50% certainty).