Itchgrass (Rottboellia cochinchinensis) control in corn with primisulfuron
1998
Sodsai Changsaluk
Pot experiment was carried out to study itchgrass control with primisulfuron at 40 g ai/ha. It was found that primisulfuron applied at 1 to 3 weeks after emergence (WAE) was the most effective control of itchgrass and reduced dry weight and plant height, while applied at 4 WAE was not effect on itchgrass dry weight but plant height was reduced. Field experiments were conducted using 8 hybrid corn varieties the result revealed that applying at 2-3 WAE which were at 3-8 leaves stage of maize plants or 3-7 leaves of itchgrass gave the most effective control of itchgrass, 51-88 percent. Pioneer 3021 corn was the most susceptible to primisulfuron but DK 888, Hercules 40 and Tevada 77 corn were tolerant to this herbicide and produced the same amount of grain yield as hand weeding. Pre-emergence application of pendimethalin at 1,650 g ai/ha showed completely control of itchgrass in pot experiment. In field experiment, ammonium sulfate, Latron CS-7 and Sylgard 309 improved primisulfuron at 40 g ai/ha for controlling purple nutsedge. Latron CS-7 in combination with primisulfuron at 30 g ai/ha improved its efficacy for tropical spiderwort (Commelina benghalensis L.) control, but did not injure to corn plants. However Latron CS-7 in combination with primisulfuron at 40 g ai/ha reduced corn yield. Three herbicides; 2,4-D, triclopyr, and fluroxypyr were not increase the activity of primisulfuron at 20 and 40 g ai/ha for itchgrass control, but primisulfuron at 20 g ai/ha in combination with the same herbicides privided better control of purple nutsedge than primisulfuron alone. Furthermore, 2,4-D, triclopyr, and fluroxypyr gave tropical spiderwort, and painted spurge control more effectively than primisulfuron alone but poor itchgrass control. Triclopyr caused high phytotoxic to corn plants, reduced yield, plant height, 10 ears weight and 1,000 grain weight.
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