CHEMICAL CONTROL OF UNDERGROWTHS IN ONION SEEDBED (Allium cepa) IN CERRO PUNTA, PANAMA. 1998.

Abstract

The onion (Allium cepa) is a cultivation that is characterized by its poor competition with the undergrowths, those which cause reduction of the quantity, size and quality of the trasplanted seed. This is due to that this cultivation requires more time in seedbed; therefore, its behavior is very slow and permits that the undergrowths compete by light and nourishment of the soil. In countries as Mexico, they have been evaluated herbicides as linuron, oxifluorfen and oxadiazon, using water volumens of 300 liters by hectare, finding good results. In Panama, the use of herbicides in seedbed has not been successful, since the only one that it has answered to the expectations of the producing of onion has been the metazole, which has been discontinued; therefore, the producer has appealed to the utilization of paraquat before the germination of the onion seed, followed of the manual control (20 to 30 wages-day/hectare) increasing the managing costs of the seedbed, of the production, as well as the quality of the seed. For this reason, the present investigation had as objective the herbicides and dose selection more effective in the chemical control of undergrowths in onion seedbed. In the Experimental Station of the IDIAP in Cerro Punta, was established a trial with a Complete Blocks design at random, with three repetitions and 10 treatments, applied with the undergrowths presence of two to three leaves, using the variety Gladalan Brown. Of the evaluated treatments, the most promissory were the linuron (250 and 500 g of i.a./hectare); the oxadiazon (190 and 380 g of i.a./hectare) and the oxifluorfen (120 g of i.a./hectare), with a 100% of control over the present undergrowths.