Occurrence of Late Blight (Septoria apiicola Speg.) on Celery (Apium graveolens L.) in Egypt

Celery (Apium graveolens L., family Umbelliferae) is an important, annual crop cultivated mainly as medicinal plant as
well as vegetable plant in Egypt. The seeds and essential oil are very important and expensive yield components due to their usages as spice, in medicinal products and in folk medicine. Recently, the area cultivated is expanded in Beni-Suief Governorate as a result of the increase in exportation demand. Late blight (=Septoria leaf spot) caused by Septoria apiicola Speg. is a worldwide major foliage disease causing losses of 50-90% in commercial celery fields. In Egypt, symptoms of the disease started to appear at the end of March and during April 2015 on growing fieldplants in Beba and Somusta Counties, Beni-Suief Governorate. Symptoms appear as small, circular, water soaked spots on the leaves
(about 1.3 to 1.8 mm, av. 1.6 mm - diam.), often surrounded by a faint chlorotic margins (Fig.1.). After 21 to 36 days, the spots turned dark to nearly black and became filled with minute black pycnidia (Fig.1.), which were closed, pear-shaped cups partly embedded in the infected plant tissues (Fig.2.). These symptoms were usually observed on all
the foliage plant parts at the last month of the growing season and percentages of infected plants reached 60-100% in severely infected fields with disease severity ranged between 43-90%. Moreover, about 5% plants of the total growing area were completely destroyed. According to the available literature, this is the first report of this disease in Egypt.