Grapevine leafroll-associated virus (GLRaV) is a name for a group of viruses that infect grapevine.. Obscure mealybugs (Pseudococcus viburni) feed on the phloem of vines and woody-stemmed plants, especially pear and apple trees and grape vines.Some individuals are vectors for infectious pathogens and can transmit them from plant to plant while feeding; mealybug …