Monitoring physiological races of Podosphaera xanthii (syn. Sphaerotheca fuliginea), the causal agent of powdery mildew in cucurbits: factors affecting race identification and the importance for research and commerce

摘要: Identification of the physiological races ofPodosphaera xanthii (syn.Sphaerotheca fuliginea), causal agent powdery mildew in cucurbits, is based upon differing responses various melon cultigens to pathogen. Eight pathogen have been identified date USA, Africa, Europe and around Mediterranean Sea, four new were reported from greenhouse melons major growing area Japan. Plant may be affected by environmental factors such as light intensity, temperature humidity, well age nutritional status plants. The same affect accuracy reliability race identification. In an attempt overcome those obstacles, genetic diversity ofP. was studied using molecular markers. Unfortunately, no correlation found between DNA polymorphism biological tests. usefulness identification a guide for grower selecting appropriate cultivars limited because changes or shifts population are common. Such among seasons, geographic regions hosts, also within single during season. On other hand, important basic research especially commercial seed industry, which requires declaring type level resistance its products.