Chemical weed control in Kinnow orchard.
Field trials were conducted at Palampur, Himachal Pradesh, in 1983 to test the efficacy of 15 herbicide treatments, applied post-em. as directed sprays to tree basins on 5 July, and manual weeding for the control of weeds (30.9, 28.8 and 14.3% of which consisted of Imperata cylindrica, Desmostachya bipinnata and Saccharum munja, resp.) in 6-year-old Kinnow [mandarins cv. Kinnow] budded on to rough lemon rootstock on clay loam. By 90 d after treatment, monocotyledonous weed populations were reduced from unweeded control values of 9.7 plants/0.25 m2 to 2.8-7.8 plants, maximally by manual weeding or 4.807 + 0.6 kg/ha dalapon + paraquat. Dicotyledonous weeds were reduced most (from controls of 2.1 plants to 1.0 plant) by 0.75 kg diquat ± 0.8 kg 2,4-D; however, not all treatments resulted in effective control of these plants. The DW of total weeds was reduced from 763.3 g/0.25 m2 to between 43.3 and 430.0 g (i.e. with weed control efficiencies (WCE) of 43.6-94.3%), the best treatment being by manual weeding and the most effective herbicide (resulting in 146.6 g weed DW and WCE of 80.7%) being the dalapon + paraquat treatment.