دراسات على الفطرين Alternaria و Pestalotiopsis الممرضة لأوراق البطوم في بعض مواقع المنطقة الوسطى من الجبل الأخضر

الملخص EN

Mastic tree, an important evergreen and medicinal plant grown in the forest of Al-Jabal Al-Akhdar, Libya has suffered heavy losses due to leaf diseases.

Various kinds of leaf spots and blight were noted on plant leaves.

The objective of this work was to identify and determine the percent of infection and host range of fungal foliar diseases.

Four fungal species were frequently isolated from the disease symptoms.

Alternaria alternata was the most predominant fungus associated with the brown leaf spot on mastic, followed by Pestalotiopsis fici which was commonly isolated from leaf blight and P.

guepinii and P.

palmarum which were isolated from leaf tip death and silvery gray leaf spots respectively.

Koch´s postulate was verified by inoculating healthy mastic leaves.

Host range studies indicated that all fungi can infect leaves of P.

vera, P.

atlantica, and Ceratonia siliqua.

Results from the field revealed that disease incidence was quite variable between locations and seasons.

The highest percent of infection (6.4- 30.8%) was recorded in Alhamama region, and the lower level of disease incidence (3.4- 12.8%) was observed in Algariga region.

Rate of diseased leaves was about 4.2- 20.6% in spring, while they recorded 2.8- 6.0% in winter.

The records indicate that this is the first report of a fungal leaf disease of mastic shrubs in Libya