Revista Brasileira de Milho e Sorgo (Apr 2004)
CARFENTRAZONE-ETHYL SELECTIVITY FOR NORMAL AND SWEET CORN
Abstract
The objective of this work was to evaluate the selectivity of carfentrazoneethyl, a post emergence herbicide that inhibits a protoporphyrinogen oxidase (Protox) for normal and sweet corn. Experiments were set up at Embrapa Milho e Sorgo, Sete Lagoas, MG under greenhouse conditions. The experiments were carried out in a completely randomized block design with four replications. Evaluations of visual injury symptoms were done at 7 and 14 days after herbicide application (DAA), and of shoot dry matter at 14 DAA. In the first experiment, five normal corn cultivars (SHX 4001, AS 1533, DKB 747, 30 F 98, CD 302), five sweet corn cultivars (HT 1, BR 400, HT 3, BR 401, BR 402), and two carfentrazone-ethyl rates (12.5 and 25.0 g ha-1) were tested. The injury level observed was not greater than 20%. The cultivars 30 F 98 and CD 302 were the most susceptible ones. It was not detected any significant differences to shoot dry matter. In another experiment, the response of the cultivar BRS 3060 to carfentrazone rates (3.13; 6.25; 12.5; 25.0; 50.0; 100.0; 200.0 g ha-1) was tested. Regression analyses were done considering injury levels (7 and 14 DAA) and shoot dry weight (14 DAA) against carfentrazone-ethyl rates. The coefficient of determination of the regressions was higher than 0,74, showing good relationship between rates and injury level or shoot dry weight. The injury level observed was not higher than 40%. Carfentrazone-ethyl at 50 g ha-1 reduced about 7% of the shoot dry weight. The results indicate that carfentrazoneethyl have acceptable selectivity to control weeds on corn.
