ABSTRACT

Olive tree is one of the most cultivated trees over the Palestinian territories, it is

considered as the mainstay of rain-fed agriculture in Palestine. Recently and due to the

impact of the global warming, olive trees were infected with an outbreak of many pests

and pathogens. In the last decades, both olive fruit fly

Bactrocera

oleae

(Diptera, Tephritidae)

and peacock leaf spot

Spilocaea

oleagina

were reported with an unusual percentage of

infections over the olive trees. During 2015-2016, and throughout the field surveys to

investigate any unusual diseased symptoms on olives; some trees exhibited pale yellowing

on the newly formed branches, symptoms associated with viral infections such as OLYaV.

Some other trees were noticed to get yellowing and later on developed branch dieback and

stem canker and cracking syndromes. When the outer bark was removed, the affected

tissue appeared dark brown, in contrast to the yellowish green of healthy inner bark.

These symptoms were observed on both young and old trees in the northern part of

Palestine. Field and laboratory investigation revealed a heavy infestation with larvae of

Resseliella oleisuga

Targ. (Diptera: Cecidomyiidae). The infestation rate reported ranged

from 75 to 92 in some olive orchards. Pathogens were isolated and identified based on

cultural morphology. Climate changes due to the global warming might be the cause of

this outbreak; probably due to the changes in the environmental conditions favored by

the insects. To our knowledge, this is the first time this insect was reported to be widely

spread of olive trees and causing damage in Palestine. In this study several associated

primary, secondary, and saprophytic diseases were detected from the infected samples.

Mainly

Botryosphaeria

spp,

Alternaria solani

Sor.,

Aspergillus

niger

v. Tieghem,

Cladosporium herbarum

Fr.,

Fusarium solani

(Mart.) App.,

Penicillium digitatum

Sacc.,

Penicillium

italicum

Wehmer,

Rhizopus stolonifer

(Her.) Vuill.