Summary.Weed control experiments carried out in tea plantations showed that diuron at doses 2·4, 3·2 and 4·8 lb/ac a.i. resulted in better and more persistent weed control than siamazine.Shoot absorption experiments carried out on three tea jats, dark, medium and light, showed that the tea jats differed in their tolerance to both diuron and simazine, the light one being the most susceptible.A difference IN the expression of phytotoxic effects between leaf and root absorption was observed for diuron only. At equivalent doses, 2‐year‐old plants were in general more susceptible to diuron than to simazine.Diuron and simazine used alone at 2·4, 3·2 and 4·8 lb/ac a.i. or with addition of sodium chlorate at 6 lb/ac to improve the kill of emerged weeds, did not affect yield of either pruned unpruned 6‐year‐oId tea. Dalapon, on the other hand, at 6 lb/ac significantly reduced the yield of unpruned tea but not of pruned lea.Le désherbage chimique du th