I'm assuming this refers to apples or pears.

"Russeting on apples is a particular type of skin, slightly rough, usually with a greenish-brown to yellowish-brown colour. Many apple cultivars have some natural russeting, but some are almost entirely covered in it, notably the Egremont Russet. Russet apples often exhibit a scent and flavour reminiscent of nuts, and are often very sweet. Despite this, modern apple breeders rarely accept russeting in new apple cultivars. The amount of russeting can be affected by various factors including, weather, disease or pest damage and agrochemical applications (e.g., insecticides, fungicides and growth regulators)."

I think this may be an unsuccessful attempt at spelling the English "russet", but I'll try and find a Spanish reference. The English Wikipedia article links to the Spanish "manzana reineta", but this simply refers to russet varieties without mentioning that it may be an undesirable phenomenon.