*5.2.1 Powdery mildew of Cucumber*

Powdery mildew of cucumber is caused by either *Erysiphe cichoracearum* or *Leveillula taurica* (Erysiphales) and *Sphaerotheca fuliginea* [76]. Powdery mildew had been identified on cucumber fields in Nigeria [79]. There are reports on the presence of *Leveillula taurica* on cucumber fields in Kenya, Libya, Morocco and

Senegal [80]. Powdery mildew infection is one of the easiest to spot because of the specificity of the symptoms. Transmission of the fungus occurs when conidia are dispersed over long distances by wind, through the movement or planting of infected cucurbits or by alternate hosts. Typical symptoms include white powdery growth in the upper leaf surfaces and stems of infected plants [81]. The lower or young leaves are most affected but mildew can be seen on any upper part of the plant. Infected plants are usually stunted and distorted. Fruits may also experience stunted growth.
