Evaluations of Some Herbicides to Control Weeds in Potato Fields in Libya

Abstract

A study was conducted to evaluate several herbicides applied at different dates in potato crops. Three experiments were performed at Ibn Zaidon Station, Tripoli, Libya. The first experiment was in the Fall of 1989-1990 using Merka variety. The second, in the Spring of the same season using the variety Spunta and, the last experiment was performed on Merka during the Fall season of 1990-1991.

The herbicides treatments were applied pre-emergence, pre-emergence soil incorporated or post-emergence when the plants were at 4-8 leaf stage. The herbicides were applied either separate or combined.

The second experiment indicated that weed density was significantly reduced in the plots treated with bentazon combined with cycloxydim or sethoxydim. This reduction was accompanied by significant yield increase of the potato tubers. The yield was 8.61 and 8.67t/ha from the treatments of bentazon 4-cycloxydim and bentazon 4-sethoxydim, respectively. The yield of weed-free plots was 7.63 t/ha. In the third experiment the yield of the tubers was significantly increased in the plots treated with pendimethalin 4-bentazon 4-fenoxaprop-ethyl, bentazon 4-cycloxydim, and bentazon 4- haloxyfop-ethoxyethyl compared with untreated plots. The yield obtained from the above treatments was 19.7, 19.4, 20.3 and 19.0t/ha, respectively. These yields were not different from that obtained from hand weeding plots, and were consistent with the reduction in weed densities. Significant weed reduction was also observed in the first experiment, but did not change the yield of Merka tubers in the plots including control.

The increase of weed infestation in this study caused a pronounced reduction in the yield of potato tubers. Such decline varied between 10 and 40% of weed-free plots. The reduction depends on weed species present in the experimental fields and planting seasons.