Citrus variegated chlorosis (CVC): Symptoms may occur in twigs, leaves and fruits. The plants do not usually die. Symptoms can manifest on trees from nursery age to over ten years old. Symptoms in older trees (15 years) are generally restricted to a few branches. Symptoms are more obvious on 3–6-year-old trees and mainly on sweet orange cultivars. The characteristic symptoms are small interveinal chlorotic yellow spots, resembling zinc deficiency, on the upper side of mature leaves, which correspond to slightly raised gummy lesions, light to dark brown on the underside of leaves. On a newly affected tree, symptoms generally appear in sectors, whereas old infections are more uniform throughout the canopy. Fruits are much smaller than normal, very firm and ripen earlier. The growth rate of affected trees is greatly reduced and twigs and branches may wilt. When chronic, the disease can cause stunting and dieback of twigs (Laranjeira et al. 2002, Crop Protection Compendium 2005, EPPO 2005).
Pierce’s disease of grapevine (PD): on Vitis spp, the typical symptom is leaf scorching in conjunction with areas of chlorosis, progressing into necrosis at the leaf margins. However, the disease is also commonly associated with defoliation, shoot dwarfing, dehydration of fruit clusters, cane stunting, irregular maturation of cork of infected canes (leading “green islands”), and eventual plant death (Krivanek et al. 2005).
Coffee leaf scorch (CLS)