Determination of Densities and Frequencies of Problematic Weed Species in Onion Planting Areas of Ankara and Çorum Provinces

This study was conducted in 2019 order to determine the weed species, their densities and frequency of occurrences onion production areas Ankara Çorum Provinces. The surveys were carried out 78 fields, 55 23 Çorum. As a result surveys, 75 two which are parasite, belonging 28 families 64 genera, determined fields Province. with most species listed as Asteraceae (11), Poaceae (9), Fabaceae (6), Chenopodiaceae (5) Apiaceae (5). Other between 1-3 species. Of these weeds, Convolvulus arvensis L. (1.2 plants/m2), Xantium strumarium (0.50 Amaranthus retroflexus (0.40 Cuscuta sp. (0.37 parazited onion/m2), A. blitoides S. Watson (0.36 plants/m2) 5 intense According occurrence, first five as; C. (90.90%), X. (65.45%), (54.54), Chenopodium album (52.72%), albus (47.27%). In cultivation Province, 61 one is 24 51 genera determined. Poaceae,(8) Apiacea (5), Polygonaceae (4), (4); for other families, Considering per m2 common (0.80 Anethum graveolen (0.56 (0.41 Chrozophora tinctoria (L.) Raf. (0.32 spinosum (0.31 terms incidence are; (86.95), refroflexus (56.52%), Cirsium arvense Scop. (52.17%), (52.17%).