Zahra Ibrahim El-Gali^*(1) Eman Gebreal Abdul-Raff⁽²⁾ and Kamlla Abdel-Rahim  El-Wahsh⁽¹⁾

(1). Department of Plant Protection, Faculty of Agriculture, Omer AlMuhktar University, Libya.

(2). Faculty of Natural Sources and Ecological sciences, Omer AlMuhktar University, Libya.

(*Corresponding author: Dr. Zahra Ibrahim El-Gali. E. mail: zahra.ibrahim@omu.edu.ly).

Received: 10/05/2019                                Accepted: 10/09/2019

Abstract

This study was conducted during the season 2017/2018 to evaluate the infection%, disease severity of sooty mold on fig, oleander and olive trees in Omer AlMukhtar University periphery, and identification of causal disease and associated insects with it, then confirmation of fungal growth on insect’s honeydew. Visits were weekly carried out from April until November during 2017/2018, and all samples were collected and checked under light microscope and stereomicroscope for insect’s observation, honeydew and fungal growth in laboratory. Also breeding of insect on tree seedlings from egg hatching until honeydew production for fungal culture on it. The results recorded that the highest infection with insects was noticed on olive trees (75.5%), followed by oleander (56.6%), then fig trees (30.3%), respectively, while, disease severity were reached to 69%, 53% and 13.5% on olive, fig and oleander respectively. The results of fungal isolation and insect’s identification showed to finding out Alternaria alternata on leaves and two suckers’ insects were correlated with sooty mold disease. Ceroplastes rusci on fig trees and Saissetia oleae on trees of olive and oleander. The fungus A. alternata had the ability for growth on honeydew on the leaf surface as mycelium and conidia without penetration their tissues.

Keywords:  Sooty mold, Alternaria alternata, Insect scale, Trees, Libya.

Full paper in Arabic: PDF