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Forty-two isolates of Rhizoctonia spp. were obtained from onion in Amasya, Turkey. Of these, 29% were Rhizoctonia solani (AG-4), 69% were Waitea circinata var. zeae (Rhizoctonia zeae) and 2% were binucleate Rhizoctonia (AG-B). Most of the isolates were recovered from rhizosphere soil. In pathogenicity tests on onion, R. solani AG-4 caused the greatest disease severity, those of W. circinata var. zeae were moderately virulent but binucleate Rhizoctonia isolates were of low virulence. This is the first report of binucleate Rhizoctonia AG-B and W. circinata var. zeae occurring on onion in Turkey.www.blackwell-synergy.com

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Diseases, especially caused by seed borne fungi, are among the factors decreasing yield and quality of wheat. Common bunt is also an important seed borne disease of wheat worldwide. The objective of the study is to determine the effects of clove, ginger, mint, oregano and thyme oils on the fungal load of wheat seeds. In addition, effects of the oils on the germination rates of bunt spores were investigated. Blotter method was used to determine the effects of different concentrations (0.05 -10%) of the oils on fungal load of wheat seeds. After incubation at 22°C for 7 days, seeds were investigated under stereomicroscope and fungi growing on the seeds were recorded. Germination rates of bunt spores were determined after incubation on water agar with different concentrations of oils. Highest doses of clove, mint and oregano oils totally inhibited the fungal growth on wheat seeds, but they also inhibited the germination of seeds. Lower doses failed to inhibit fungi on seeds, however they decreased or totally inhibited the germination of bunt spores. As a result, it was found that plant essential oils could be used against bunt disease of wheat as an alternative to fungicides.

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The effect of electron beam treatment against fungi on naturally contaminated maize seeds depended on irradiation dose, allowing the control of maize fungal load.

Pythium lycopersicum sp. nov. has been isolated from soil samples taken in an agricultural land in the Isparta region of Southern Turkey. This oomycete is characterized by its contiguous sporangia having globose to elongated elements linked with hyphal filaments, ornamented oogonia, and monoclinous antheridia with large antheridial cells. The oomycete is reminiscent of Pythium ornamentatum described by the corresponding author in 1987 from soil samples taken in Algeria. Sequence analyses of the internal transcribed spacer (ITS) regions of rRNA show a close relationship with Pythium oligandrum and other mycoparasites possessing ornamented oogonia. Morphological and molecular features of this isolate justify its description as a new species: P. lycopersicum. When grown together with Botrytis cinerea, this oomycete shows a pronounced antagonism and suppresses the phytopathogen. The morphological details, together with the analysis of the ITS region of its rRNA, and its antagonism with some phytopathogens are discussed in this article.

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