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Description:
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Clomazone is an effective herbicide widely used for preemergence grass control in rice . However , use of clomazone on sandy textured soils of the western Texas rice belt may cause serious rice injury . When labeled for rice in 2001 , sandy textured soils were excluded . Laboratory experiments were conducted to determine the effect of soil characteristics and water potential on plant -available clomazone and rice injury . A centrifugal double -tube technique was used to determine plant -available concentration in soil solution (ACSS ) , total amount available in soil solution (TASS ) , and Kd values for clomazone on four soils at four water potentials . A rice bioassay was conducted parallel to the plant -available study to correlate biological availability to ACSS , TASS , and Kd . TASS was significantly different in all soils at the 1 % level of significance . The order of increasing TASS for the soils studied was Morey Edna Nada Crowley which correlated well with soil characteristics . Two field experiments at three locations were conducted in 2002 and 2003 to determine the optimum rate range that maximizes weed control and minimizes crop injury across a wide variety of soil textures and planting dates . At Beaumont , Eagle Lake , and Ganado , TX , preemergence application of 0 .41 to 0 .56 , 0 .38 to 0 .43 , and 0 .36 to 0 .42 kg ha -1 clomazone , respectively , provided optimum weed control with minimal rice injury . Data suggests that clomazone is safe to use on rice on sandy textured soils . Injury may occur , but , rates suggested from this research will minimize injury and achieve excellent weed control . As a result , amendments to the herbicide label will allow clomazone use on sandy textured soils giving rice producers more flexibility and access to another effective herbicide . |