Determination of the important weed species, their intencities and frequencies in hazelnut cultivated area of Düzce provice

Hazelnut has an important role in terms of crop production in the Düzce. Weeds are one of the important plant protection problems in hazelnut production. This research was conducted between April and July in 2021 in hazelnut gardens of Düzce City in order to investigate the weed species, intensity and the frequency of occurrence. To do this, surveys were realized on an area covering 50 gardens in 8 towns of Düzce City. As a result, 103 weed species of 31 families were investigated. Among these, Potentilla reptans with 35,46 plants/m², Poa pratensis with 12,15 plants/m², Bromus hordeaceus subsp. hordeaceus with 11,97 plants/m², Cynosurus cristatus with 10,52 plants/m², Bromus sterilis with 8,97 plants/m², Hordeum bulbosum with 8,43 plants/m², Trifolium pratense var. pratense with 6,17 plants/m², Holcus lanatus with 5,87 plants/m², Alopecurus myosuroides subsp. myosuroides with 5,84 plants/m², Trifolium campestre with 5,75 plants/m² were the most frequently investigated 10 species. Related to frequency first 10 weed species determined in surveys were; Potentilla reptans (%81,80), Oenanthe silaifolia (%78,34), Lapsana communis (%60,72), Convolvulus arvensis (%51,37), Rubus tereticaulis (%43,87), Geranium pyrenaicum (%38,2), Trifolium campestre (%37,1), Trifolium pratense var. pratense (%32,13), Conyza canadensis (%31,81), Urtica dioica subsp. dioica (%31,72).