DETERMINATION OF SOME PATHOGENS OF DATE PALM OFFSHOOTS DEATH PHENOMENON AND THE EFFECT OF ِSALINITY AS A PREDISPOSITION FACTOR FOR DISEASE

Al-Zahra J. Al-Mohamdawi, Abid; S. Juber, Kamil

	DETERMINATION OF SOME PATHOGENS OF DATE PALM OFFSHOOTS DEATH PHENOMENON AND THE EFFECT OF ِSALINITY AS A PREDISPOSITION FACTOR FOR DISEASE
The Iraqi Journal of Agricultural Science
Article 1, Volume 41, Issue 2, 2010, Pages 105-116
Authors
Abid Al-Zahra J. Al-Mohamdawi; Kamil S. Juber
Abstract
This study was conducted to detect date plam offshoots death phenomenon, isolation and identification the fungi associated with declined offshoots in the middle of Iraq, evaluation their pathogencity, The results of field survey covered twelve locations (Baghdad, Kerballa, Babylon, Diala, EL-Qadjsia and EL-anbar) revealed the presence of this phenomenon in all studied locations and the percentage of offshoots death ranged between 13% to 42%. Microbial analysis showed that ten fungal species (Alternaria alternnata, Chalaropsis state of Ceratocystis radicicola, Cylindrocarpon album, C. destructans, C. destructans var. crassum, Drechslera australinsis, Fusarium graminearum, Pythium aphanidermatum , Rhizoctonia solani and Scytilidium thermophilum) belonged to eight genuses associated with declined offshoot, roots in varied percentage of occurency. The isolation of the species belonged to the genus cylindrocarpon was the first in Iraq. The fungus C. destructans was isolated from all tested samples with highest frequency isolation percentage 48.75%, followed by C. destructans var. crassum and C. album which isolated from nine and seven samples 33.88% and 32.50% respectively, while the other fungi isolated from one to six samples with isolation frequency ranged between 5% to 25%. The results also showed that isolates AZ1, AZ2 and AZ3 were more virulence (0, 2 and 3 seeds germinationl). The results of the effect of 8 fungi isolates C.destructaus (AZ1), C. destructans var. crassum(AZ2), C.album (AZ3), C. state of ceratocystis radicicola (AZ4), F.graminearum (AZ5), D.australiensis (AZ6) , A. alternata (AZ7) , P.aphanidermatum (AZ8) on sixty days old date palm seedlings revealed that all tested isolates induced significant increment in disease severity 25-85% as compared with control untreated treatment 0% , and the isolate AZ1 was the superior 85% followed by isolate AZ4 75%. The tested pathogenic fungi also induced significant reduction in all tested plant growth parameters compared to control treatment, and isolate AZ1 was the more effective which reduced the shoots & roots length and fresh & dry weight of shoots to 16, 3.75cm, 2.07 and 0.15 gm respectively, compared to 44.4, 55cm and 6.94 , 2.2gm in control treatment respectively. The results of the interaction between salinity and fungal pathogens showed that the all tested levels of salinity 2, 4 and 8 dc/m increased the virulence of the fungal pathogens compared to that of the fungal pathogens only, also significant reduction in plant growth parameters was recorded.

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