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Occurrence and characterization of fungi and oomycetes transmitted via potting mixtures and organic manures |
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| Authors: | AM Al-Sadi FA Al-SaidAH Al-Jabri IH Al-MahmooliAH Al-Hinai AWAM de Cock |
| Institution: | a Department of Crop Sciences, College of Agricultural and Marine Sciences, Sultan Qaboos University, P.O. Box 34, Al Khod 123, Sultanate of Oman b Center for Environmental Studies and Research, Sultan Qaboos University, Oman c CBS-KNAW, Fungal Biodiversity Center, P.O. Box 85167, 3508 AD Utrecht, Netherlands |
| Abstract: | A study was conducted to investigate the most common fungal and oomycete pathogens introduced into farms in Oman via potting mixtures and organic manures. A total of 37 commercial types of potting mixtures (2 local and 35 imported from overseas), 4 commercial types of organic manures and 11 non-commercial types of organic manures were included in the study. Identification of the isolated species was based on morphological characteristics, except for the most common species which were further identified using sequences of the internal transcribed spacer region of the ribosomal DNA (ITS rDNA). Fusarium spp. (14%), Pythium aphanidermatum (3%), Alternaria spp. (5%), Helminthosporium spp. (5%) and Cladosporium spp. (3%) were recovered at different frequencies from samples of potting mixtures. Fusarium solani (40%) and Fusarium equiseti (47%) were recovered at high frequencies from samples of organic manures. Isolations from organic manures also yielded Pythium periplocum (7%), Rhizoctonia solani (7%), Fusarium lichenicola (7%), Helminthosporium spp. (27%) and Alternaria spp. (27%). Trichoderma spp., Penicillium spp., Aspergillus spp. and Rhizopus spp. were found to be common in samples of potting mixtures and organic manures. Investigating sensitivity to hymexazol among 9 isolates of F. equiseti and 13 isolates of F. solani revealed variations among different isolates. The EC50 values ranged from 1 to over 1200 (avg. 192 μg ml−1) for F. equiseti isolates and from 135 to 789 (avg. 324 μg ml−1) for F. solani isolates, indicating presence of resistance to this important fungicide among some Fusarium isolates. This appears to be the first report of contamination with R. solani, P. periplocum, F. solani, F. equiseti and F. lichenicola of organic manures. This study appears to report for the first time F. lichenicola in Oman and appears to be the first report of occurrence of resistance to hymexazol among F. equiseti and F. solani isolates. |
| Keywords: | Fertilizer Fusarium ITS region Pythium Tachigaren |
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