Impact of Some Herbicides on Potato Weeds and on Yield

Mouzahem Al Dahoul 
General Commission for Scientific Agricultural Research-
Salamiyah Research Center
Tishreen University, Faculty of Agriculture


An experiment was conducted during 2004/2005 spring and 2003/2004 autumn; on potato crop at Hama Research Center. A number of herbicides were used in this experiment pre-plantation and emergence:
Prometryne: 750 g  a.i /ha, Linuron: 1250 g  a.i /ha, Isoxaflutol: first treatment 67.5g  a.i / ha; Isoxaflutol: second treatment 90 g  a.i /ha; mixture of Isoxaflutol and Linuron: 37.5 + 750 g  a.i /ha, Cyanazine: 800 g  a.i /ha ; mixture of Cyanazine and Linuron: 800 + 750 g  a.i /ha, and Oxadiazon: 1250 g  a.i /ha, and one herbicide used post-plantation and post-emergence: Ammonium glyphosinate with 400 g  a.i /ha. Weeds were manually removed three times and weedy control experiment as well. Broadleaved weeds were dominant with rare narrow leaved weeds.
The result in spring and autumn showed that the number and dry weight of weeds 1 m² were not effective with potato varieties. All herbicide treatments were better than the weedy control experiment with significance; in decrease number and dry weight of weeds per 1 m². An excellent results in controlling broad weeds during spring was achieved 60 days post-treatment with herbicides; to (Oxadiazon, Isoxaflutol if used alone with two rates or mixed with Linuron); with dry weeds weight activity 99, 89, 92, and 80% respectively.  Isoxaflutol herbicide if used alone with two rates or mixed with Linuron was better than herbicides during autumn, with dry weeds weight activity (60 days post treatment with herbicides) 92, 93, and 90% respectively. In spring and autumn; Ammonium glyphosinate herbicide was achieved lower activity compared with all herbicides.
Phytotoxicity of herbicides was noticed on varieties Sponta and Diamont during both spring and autumn; especially herbicide Isoxaflutol in autumn was very light to light faded later.
Sponta was better yielded than variety Diamont in both spring and autumn with significantly differences in spring. Potatoes in all herbicide treated experiments gave better significance yields than the potatoes in weedy control experiment. Yield of potatoes from all treatments without Cyanazine and manually weeded treatment in spring were close without significantly differences, and all the better herbicides were Oxadiazon, Isoxaflutol if used alone with two rates or mixed with Linuron. In autumn, only yield of potatoes from Oxadiazon and manually weeded treatment were close without significantly differences.
Size tubers in both spring and autumn; number and weight of small tubers (less than 35 mm diameter) for all treatments and weedy control experiment were close without significantly differences. Number and weight of medium and big tubers (between 35 – 55 mm diameter for medium tubers, high of 55 mm diameter for big tubers) for all treatments in spring and autumn better than weedy control experiment with significantly differences, and all the better herbicides were Oxadiazon, mixtures of Cyanazine and Linuron), (Isoxaflutol and Linuron) gave number and weight of medium tubers in course; more than the rest herbicides.
Weeds control manually or chemically rose potato net yield comparative with weedy control experiment in spring and autumn, potato net yield for herbicides  ( Oxadiazon, Isoxaflutol}} if used alone with two rate or mixed with Linuron ) better than manually weeded treatment in spring, but in autumn only herbicide Oxadiazon closed to weeded treatment .
Key words: Herbicides, number of weeds, dry weight of weeds, phytotoxicity, weeds, yield, number of tubers, weight of tubers.