Late blight, caused by Phytophthora infestans, is one of the most destructive potato diseases in the world. In Yemen, identification of P. infestans still depends on a visual survey and external examination of late blight symptoms.
In Yemen, the characterization of the P. infestans population is still largely unknown, and most of the previous studies on P. infestans seemed to rely on a visual scan survey and external examination of late blight symptoms, including Kamal and Agbari14. A recent study tried to isolate and identify P. infestans using morphological characterization and molecular identification.
Visual observation of late blight symptoms, which are often water-soaked, brownish-black, and irregularly shaped lesions on the edges of the leaf, and white growth (sporulation) evident on the abaxial surface of the leaf lesions, is the first step toward the detection of P. infestans at early stages of infection.