[Weed control in cassava [Thailand] by screening of pre-emergence herbicides, pre-and postplant application of dalapon, certain pre-emergence herbicides applied, certain newly developed herbicides]
Umporn Suwunnamek | Chamlong Chiamchamnancha | Sinchai Swasdichai (Kasetsart Univ., Bangkok (Thailand). Faculty of Agriculture)
The results of the experiment on the screening of pre-emergence herbicides in cassava indicated the following: (1) chemicals which were found safe on cassava with moderate control of weeds were napropamide at 1.5-3 kg ai/ha, linuron 2, thiobencarb 0.75-1.5, thiobencarb + prometryn (10:1) 1.5, cyanazine 0.75-1.5, methoprotryn 3, alachlor 0.75-1.5 and butachlor 1.5 kg ai/ha. (2) chemicals which were slightly phytotoxic to the plants at the beginning but found safe at harvest without yield reduction were metholachlor at 1-2 and fluometuron 2-4 kg ai/ha. The treatments provided a good weed control. (3) chemicals which were found safe at the beginning but tended to be slightly toxic to the plants of harvest-were nitrofen at 2-4, diuron 0.75 and butachlor at 3 kg ai/ha. The case of trifluralin was probably due to the method of application (soil incorporation) interfered with the root growth; and (4) oxadiazon at 0.8 and diuron at 1.5 kg ai/ha resulted in moderately toxic effect to the plants and tended to reduce yield
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