Evaluation of in vitro antifungal activity of potassium bicarbonate on Rhizoctonia solani AG 4 HG-I, Sclerotinia sclerotiorum and Trichoderma sp.

The effect of increased concentrations of potassium bicarbonate (KHCO3) as a possible alternative to synthetic fungicides for controlling Rhizoctonia solani AG 4 HG-I and Sclerotinia sclerotiorum was evaluated in vitro, in this study. In addition, the effect of potassium bicarbonate on Trichoderma sp., a natural antagonist on R. solani AG 4 HG-I and S. sclerotiorum was determined. Potassium bicarbonate substantially inhibited (P<0.05) the growth of the three fungal strains. Mycelial growth of R. solani AG 4 HG-I significantly decreased as the concentration of bicarbonate increased, especially at concentrations greater than 200 mM. Similarly, mycelial growth of both S. sclerotiorum and Trichoderma sp. dramatically reduced in increasing concentrations of KHCO3. Mycelial growth of either fungi was completely inhibited when exposed to 100 mM bicarbonate. In addition, KHCO3 concentrations higher than 10 mM caused significant (P<0.05) reduction of the sclerotium formation of S. sclerotiorum. Also, sclerotium germination and de novo sclerotium formation were significantly inhibited as the concentrations of KHCO3 increased. As a result, it was concluded that potassium bicarbonate was an alternative chemical agent for  controlling R. solani AG 4 HG-I and S. sclerotiorum. Also, KHCO3 was found to have negative effects on Trichoderma sp.Key words: Antifungal effect, KHCO3, soil borne pathogens, sclerotium germination

A new host for Fusarium algeriense causing crown and root rot on barley in Kyrgyzstan

After maize, wheat and rice, barley is the most widely planted and economically important cereal crop in the Kyrgyzstan’s highlands (Usubaliev et al., 2013) and worldwide. In two barley fields in the Manas district of Bishkek, Kyrgyzstan, diseased plants exhibiting crown and root rot, stunting and brown discolouration on internodes were observed in 2020. Disease incidence was approximately 5% in the two fields

First report of Cylindrocarpon liriodendri on kiwifruit in Turkey

Erper, I.; Tunali, B.; Agusti Brisach, C.; Armengol Fortí, J. (2011). First report of Cylindrocarpon liriodendri on kiwifruit in Turkey. Plant Disease. 95(1):76-77. doi:10.1094/PDIS-09-10-0623S767795

Phytotoxins produced by Pestalotiopsis guepinii, the causal agent of hazelnut twig blight

The main lipophilic phytotoxic metabolite was isolated from the culture filtrates of Pestalotiopsis guepinii, the fungus causing twig blight of hazelnut. The metabolite was spectroscopically identified as pestalopyrone, a pentaketide that it was originally identified as a minor toxin produced by Pestalotiopsis oenotherae. The toxic activity of pestalopyrone was compared with that of nectriapyrone, a structurally related monoterpenoid recently isolated from Phomopsis foeniculi, and that of the new dihydro-derivative of nectriapyrone. The high phytotoxic activity of nectriapyrone and its dihydro-derivative on three non host plants, showed that the double bond of the 1-methylpropenyl group at C-6 of the aromatic ring is inessential for its activity, while the much lower activity of pestalopyrone showed that the methyl group at C-3 of the same ring is an important structural feature. The high molecular weight hydrophilic phytotoxins produced by this fungus are reported for the first time