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Abstract
This study was done under laboratory and greenhouse conditions in the Plant Pathology Department Faculty of Agriculture, Cairo University and Plant Pathology Research Institute, Agricultural Research Center, Giza, Egypt.
Roses (Rosa hybrida L.) are grown as garden plants, for the cut-flower industry, and as a source of natural fragrances. Many modern cut-flower rose cultivars were selected for long vase life, flower shape, and color. Intensive breeding has also generated garden cultivars that have an intense “rose” scent.
1. Biological Characters
a. Virus isolation and propagation
Prunus necrotic ringspot virus (PNRSV) was isolated from naturally infected rose plants collected from the experimental farm (Faculty of Agriculture, Cairo University). The causal virus induced necrotic ringspot on leaves, bud failure, color breaking and streaked petals at the later stage of virus infection yellowing of infected leaves was noticed. Prunus necrotic ringspot virus was biologically purified through several purification techniques and it was purified from infected Gompherena globosa.
b. Host range studies
Host range studies revealed that, PNRSV infected at least eight plant species and cultivars belonging to five families.
Prunus necrotic ringspot virus PNRSV was mechanically transmitted easily to rose plants and to other differential host plants.
c. Virus incidence in rose fields.