grapevine leafroll-associated viruses grapevine leafroll-associated viruses grapevine leafroll-associated virus (glrav) is a name for a group of viruses that infect grapevine. grapevine leafroll-associated viruses scientific classification (unranked): virus realm: riboviria kingdom: orthornavirae phylum: kitrinoviricota class: alsuviricetes order: martellivirales family: closteroviridae groups included grapevine leafroll-associated virus 1 grapevine leafroll-associated virus 2 grapevine leafroll-associated virus 3 grapevine leafroll-associated virus 4 grapevine leafroll-associated virus 7 grapevine leafroll-associated virus 13 cladistically included but traditionally excluded taxa other viruses in closteroviridae 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-spread grapevine leafroll associated virus type iii (grlav-3), in particular, has wreaked havoc among the grapes of new zealand, reducing the crop yield of infected vineyards by up to 60%. the biggest problems in grapevine leafroll disease are reduced grape yield, altered grape ripening, and altered grape chemistry.: 623 leafroll viruses are associated with rugose wood condition of grapevine.