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Öz Bu çalışmada odun sirkesinin toprak düzenleyici ve hastalık önleyici olarak tarımsal amaçlı kullanılabilirliğinin ortaya konulması amaçlanmıştır. Çalışmanın birinci aşamasında sera denemesi kurularak farklı uygulama şekillerinde odun sirkesinin buğday bitkisi gelişimi ile bazı toprak özellikleri üzerine etkisi araştırılmış, ikinci aşaması olan Biyosit denemesinde ise farklı dozlarda (% 0.5, 1, 1.5, 2, 3 ve 4) odun sirkesinin şeker pancarı yaprak lekesi hastalığı etmeni Cercospora beticola'ya karşı etkinliği in-vitro çalışmasıyla ortaya konulmuştur. Sera denemesinde yetiştirilen buğday bitkisinin yaş ve kuru ağırlıkları ile azot ve fosfor kapsamları, toprağın toplam azot, NH 4 +-N ve NO 3-N değerleri en düşük kontrolde, en yüksek ise odun sirkesi ile kaplanmış tohum+yapraktan uygulanan odun sirkesinde belirlenmiştir (p < 0,05). Sera denemesinde tüm odun sirkesi uygulamaları toprakların pH, EC, OM, kireç, P ve K değerlerini kontrole göre değiştirmiş olmasına rağmen sadece fosfor kapsamı önemli derecede (p < 0,05) artmıştır. Biyosit denemesi sonuçlarına göre, odun sirkesi uygulamaları, % 0,5 dozda uygulanan hariç C. beticola gelişimini in-vitro koşullarda tamamen engellemiştir. Odun sirkesinin % 0,5 uygulama dozunda ise yüksek virülensliğe sahip C. beticola izolatlarının gelişimini % 77,4 ve % 91,1 oranında engelleyebildiği tespit edilmiştir. Bir başka ifade ile odun sirkesinin düşük doz uygulamalarının bile virülensliği yüksek olan C. beticola izolatlarının gelişimini büyük oranda engelleyebildiği görülmüştür. Çalışmada elde edilen veriler doğrultusunda odun sirkesinin biyosit olarak in-vivo koşullarda denenmesinin yararlı sonuçlar verebileceği kanısına varılmıştır.

The pathotypes of Cercospora beticola, causal agent of sugar beet leaf spot disease, were identified by application of pathogenicity test using 100 isolates obtained from the provinces with intensive sugar beet cultivation. For the identification of pathotypes, five sugar beet cultivars were used each with different resistance factors. Cultivar reactions were determined by inoculation of cultivars with the isolates under controlled conditions and measuring disease severity on the 15 t h day according to the 1-9 KWS Scale. Based on the reactions of the five cultivars, a total of 15 pathotypes were detected. All employed sugar beet cultivars were resistant to Pathotype no:1 comprising most of the isolates. Genetic diversity of the causal agent was characterized by AFLP reaction. The products acquired at the end of AFLP reaction were detected by means of Beckman CEQ 8800 DNA Capillary Series Analysis and the results obtained were evaluated according to the similarity index UPGMA. For the genetic analysis of C. beticola isolates, 9874 polymorphic fragments of sizes between 100 and 500 bp were analysed which were generated by nine primers. The dendrogram derived from AFLP analysis depicted the existence of five different subgroups. The polymorphism rate among isolates was 91.13% and the dendrogram distribution of the pathotypes obtained by pathogenicity indicated that pathotypes were not discriminated and did not compose any groups.

In July 2009, a leaf blotch disease was observed on sorghum in Sakarya Province, Turkey. Disease incidence and severity were rated at 45% and 25 to 75%, respectively. Typical symptoms included elliptical, straw-colored, necrotic lesions with darker margins. The lesions eventually coalesced, resulting in drying of leaves. A fungus was isolated from the lesions on potato dextrose agar (PDA) incubated under near ultraviolet light for 12 h daily at 22°C for 2 weeks. Flexuous conidiophores of the fungus were solitary or produced in small groups. They were geniculate with numerous well-defined scars, medium to dark brown, ≥300 μm long, and 4 to 9 μm thick. Five to eight or more conidia were produced on the apices of the conidiophores. The conidia were straight, oblong or cylindrical, rounded at the ends, golden brown at maturity except for a small area just above the dark scar, pseudoseptate, and 20 to 31 × 7.5 to 12.5 μm (1). The causal fungus was identified as Bipolaris spicifera (Bain) Subram. (teleomorph Cochliobolus spicifer Nelson). The identification was confirmed with specific PCR primers (Bipol-1 F: 5′-CAGTTGCAATCAGCGTCAGT-3′, R: 5′-AAGACAAAAACGCCCAACAC-3′, Bipol-2 F: 5′-GTGTTGGGCGTTTTTGTCTT-3′, R: 5′-CCTACCTGATCCGAGGTCAA-3′, Bipol-3 F: 5′-GATGAAGAACGCAGCGAAAT-3′, R: 5′-AAGACAAAAACGCCCAACAC-3′). These primers were designed by the authors using Primer3 primer design software and sequences of B. spicifera found in GenBank. PCR products were amplified from nuclear DNA of the cultured fungus and were sequenced after cleaning with a Beckman 8000 CEQ DNA sequencer. Sequences amplified using Bipol-1 and Bipol-2 showed 99 to 100% similarity with B. spicifera sequences from GenBank. The DNA sequence amplified using Bipol-2 was deposited in GenBank (Accession No. HQ538774). B. spicifera has been reported previously as pathogenic in Africa, North and South America, Asia, Australia, Oceania, and the West Indies on Agrostis, Avena, Cymbopogon, Cynodon, Dactylis, Desmostachya, Eleusine, Holcus, Hordeum, Oryza, Panicum, Pennisetum, Phleum, Poa, Saccharum, Sorghum, Triticum, and Zea spp. (3). Pathogenicity tests were conducted on sorghum (Sorghum bicolor (L.) Moench) and Sorghum × sudangrass hybrid cultivars. From PDA cultures, conidia were collected in sterile distilled water with a concentration of 3% Tween 20. Twenty-five plants (five per pot) were inoculated by spraying the conidia (105 ml–1) onto 21-day-old plants, which were then maintained at 25 ± 2°C in a greenhouse following 48 h in a humid chamber. The test was repeated once. Control plants were sprayed with sterile distilled water. Typical symptoms (2) were obtained from all inoculated plants 7 days after inoculation. No symptoms developed on the control plants. The pathogen was reisolated from inoculated leaves to fulfill Koch's postulates. To our knowledge, this is the first report of B. spicifera on sorghum in Turkey. References: (1) M. B. Ellis. Dematiaceous Hyphomycetes. Commonwealth Mycological Institute, Kew, Surrey, England, 1971. (2) H. Koo et al. Plant Pathol. J. 19:133, 2003. (3) A. Sivanesan. Mycologia Papers 158:1, 1987.

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