The relationships of weeds and their distributions with ecological factors in hazelnut orchards in Ordu

Ordu Province ranks first in the world and in Türkiye in terms of hazelnut production. In this study, the prevalence and density of problematic weed species in hazelnut orchards in the province of Ordu and the influence of ecological factors on the distribution of weed populations was investigated. In this direction, the study was carried out in 2021-2022 in two different survey periods in a total of 75 different hazelnut orchards, divided into three agro-ecological regions according to the geographical location of the orchards (height and distance to the coast) to represent the research zone. The weed species identified during the surveys were associated with climate and soil characteristics and the data obtained were analyzed by using the CANOCO (Program for Analysis and Visualization of Multiple Ecological Data) and SPSS (Statistical Package for the Social Sciences) package programs together with multivariate analyses and related distribution characteristics. To reveal the effects of soil and climate characteristics on weeds, the data obtained were evaluated by the Canonical Correspondence Analysis (CCA) method. A total of 194 weed species belonging to 49 families were detected as a result of the two-year surveys. The weed species with the highest frequency (%) and density (plants/m2) in the first period (April-May) was Bellis perennis L. and in the second period (August-September) was Urtica dioica L. Rumex crispus L. and U. dioica, which were considered by producers to be the most problematic, especially due to their high frequency and density, were positively correlated with organic matter, while Pteridium aquilinum (L.) Kuhn and Dryopteris filix-mas (L.) Schott were identified as indicator species because they were negatively correlated with lime, Ca, EC and pH.