**2. Review of literatures**

### **2.1 Cucumber mosaic virus**

#### *2.1.1 Symptoms*

The pathological symptoms of *Cucumovirus Cucumber Mosaic Virus* are described, which are characterized by the yellowing and mottling that spreads on cucumber leaves and also on the fruits (**Figure 1**), which is a yellow mottling that affects all leaves and after infection the leaves are deformed in addition to stunting, which is accompanied by gradual plant degradation and curling of the leaves, as well as surface roughness. The outer layer of the leaf and the appearance of small prominent growths, these growths are clearly between the small veins [11]. Mosaic cucumber is from the Cucumovirus group that works on the appearance of mosaics and mottles on their families. Gibbs and Harrison [12] stated that this virus causes green mosaic or alternating green and yellow colors with each other on cucumbers.

The virus causes symptoms of bundling veins and deformation of the leaves, in addition to the appearance of mosaic and the curvature of modern leaves, and the necks of the leaves are reduced and accompanied by deformation of the fruits on

**FIgure 1.** *CMV pathological symptoms.*
