Leaf-yellowing in combination with corm necrosis in freesia caused by bean yellow mosaic virus: Factors involved in syndrome development

In freesia cv. Aurora grown in the field for cutflower production, a disease occurred with symptoms of leaf-yellowing in combination with corm necrosis (LYCN). It is shown that this disease is caused by bean yellow mosaic virus (BYMV).No differences in symptoms of LYCN were observed between the freesia cultivars Aurora, Imperial and Rose Marie. Most BYMV isolates gave rise to LYCN; the isolates from crocus andIxia sp. did not. LYCN was stimulated by a high BYMV concentration in the inoculum, a temperature above 20°C, inoculation soon after emergence of the freesias, and by the absence of freesia mosaic virus. Freesias with mosaic symptoms and infected with a cross-protecting BYMV strain, did not show symptoms of leaf-yellowing and/or corm necrosis after inoculation with BYMV-Cm. The presence of the unknown agent causing leaf necrosis in freesias did not have an influence on symptom development after infection with BYMV.