Effect of common cocklebur (Xanthium strumarium L.) extracts to some fungal and bacterial plant pathogens

Common cocklebur (Xanthium strumarium L.) is one of the major weeds in the World due to toxic components it contains and damage to crops. In this study, it was aimed to investigate the effects of toxic substances in the structure of common cocklebur on two fungi and two bacteria, which are plant pathogens, and to contribute to the biopesticide studies, which are alternative to chemical control. The seeds of common cocklebur were collected from their habitat in July – September 2016 in Van, and then the laboratory studies were carried out in 2017. Some of the collected seeds were planted in pots to obtain the vegetative parts of the plant, while the rest of the vegetative parts was collected from their habitat during the seedling period. The collected plant materials are washed, dried, and then ground to be used for extracting. 0, 10, 20, and 40% concentrations of water and methanol extracts obtained from the ground seeds, and vegetative parts of the common cocklebur were prepared. Also, the effects on Fusarium wilt pathogen Fusarium oxysporum f.sp. melonis, and root rot pathogen Rhizoctonia solani AG-3 as fungi, and fire blight pathogen Erwinia amylovora, and branch cancer in stone-fruits pathogen Pseudomonas syringae pv. siyringae as bacteria were investigated. In this study, the two bacteria were affected by none of the extracts of the common cocklebur. While fungi were not affected by water extracts, however, they were affected by methanol extracts. While the methanol extracts obtained from the seeds did not affect R. solani AG-3, the methanol extract obtained from the vegetative parts inhibited the development of the fungus by 52%. While the methanol extracts from the vegetative parts did not affect the F. oxysporum f.sp. melonis, the methanol extracts from the seeds inhibited the development of the fungus by 29%. In conclusion, it has been found that the methanol extracts obtained from common cocklebur may affect specific fungal pathogens but not bacterial pathogens. Keywords: Common cocklebur, Erwinia amylovora, Fusarium oxysporum f.sp. melonis, plant extract, Pseudomonas syringae pv. Siyringae, Rhizoctonia solani, Xanthium strumarium.