Pear russet caused by pear rust mite, Epitrimerus pyri (Nalepa), in Valais.
Pear russet, caused by feeding by Epitrimerus pyri, was studied in Switzerland during 1989-90. In the most serious cases, 90% of fruit were downgraded because of mite damage. Populations of >100 mites/pear were observed on young fruit. At this time populations were greater on fruit than on leaves.