Phenology of hedge parsley (Torilis arvensis) based on growing day degree in Kermanshah

Hedge parsley(Torilis arvensis)is an annual weed from Apiaceae family, which is considered as a weed of summer crops in Iran. This experiment was conducted to investigate the phenology of this weed at the research farm of the Faculty of Agriculture, Razi University of Kermanshah. Weed seeds were cultivated every two weeks from February 21, 2018 to May 1, 2018. The phenological stages were recorded from emergence to the end of seeding stage, including emergence, stemming, flowering and starting and completing the seeding. At the end of the experiment, the period of each phenological stage was calculated based on the day and the growing degree day. The results showed that the shortest and longest stages of development of this weed were from flowering to starting the seeding (7.6 days) and emergence to stemming (50.4 days). The results also showed that Torilis arvensis is a spring weed that completes its phonological stages in 178 days (equal to 1975.6 growing degree days). The results show that the best time to control this weed is late spring (before flowering).