An experiment laid in a Randomized Complete Block Design with 4 blocks and 5 treatments, was done at Kutsaga Research Station in the 2012 / 2013 season to study the impact of time of weeding on tobacco production. The treatments comprised of different times of weed control with a weed free treatment as the control. The variables measured were stalk heights at 5, 6 and 7 weeks after planting and, leaf expansion measurements were also recorded at 9, 10 and 11 weeks. Leaf yield was measured at untying using a digital scale. Results showed that Tobacco stalk heights were affected at 5 W.A.P since significant differences ( ) were noted among the treatments. Suppressive effects of weeds were shown at 6 and 7 W.A.P due to effective competition (RCI > 0) in all other treatments excluding the control. There were significant differences ( ) among the treatments on leaf expansion at 9, 10 and 11 W.A.P. The treatment weeded at 4 W.A.P showed leaf yield that was significantly higher (L.S.S = 270.8) than the treatment weeded at 2 W.A.P. Basing on the 3 reaps recorded, time of weeding had an influence tobacco yield. 1. Introduction Yield of tobacco depends on the implementation of good agronomic practices and good management of insect pests and weeds [1]. Tobacco yield loss due to weed competition is the most important factor that causes yield and quality reduction. Weed infestation of broad-leaved grasses and sedges in tobacco growing areas of Zimbabwe has reduced the primary industry productivity and profitability, and seriously limits the long-term sustainability of the crop [2]. Weeds compete directly with the desired crop for nutrients, water, light, carbon dioxide, and oxygen, and this competition significantly reduces crop yield and quality [3]. Weed suppressive impacts on tobacco are becoming a huge problem for the large commercial famers and small scale farmers. This can be largely attributed to the presence of competitive weeds and lack of capital to improve technologies of controlling them [4]. Wilson [5] estimated a 77% yield reduction and 10% quality reduction due to weed infestation in tobacco at various unknown densities of various weed species. Niell [6] also reported 12% loss due to vigorous weeds at 2-week growth stage and 64% yield loss when weeds were left in the critical weed free period of 2–6 weeks. Tobacco production at low input costs of weed management has been reported by Klingman [7] who observed a significant low gross return per unit area of the land than tobacco at high input cost of weed control. If weed management is not improved,
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