Control of Italian ryegrass by pre- and post-emergence herbicides in barley

In two glasshouse experiments, range of herbicides was applied as pre-or post-emergence to examine their effect in controlling Italian ryegrass (Loluim multiflorum) grown with barley. In experiment 1, treatment by one of the three herbicides named, chlorotoluron, controlled Italian ryegrass (L. multiflorum) \significantly (P<0.01). However, the three herbicides differed significantly (P<0.05) in their dose. Chlorotoluron gave effective control of L. multiflorum at dose of 2 kg/ha with less than 10% of mean of ryegrass plants/pot survived and only a slight damage on barley was observed. Isoproturon and methabenzthiazuron were less effective in controlling the weed as more than 30% of L. multiflorum plants survived at different doses applied while barley plants were not affected significantly by the chemicals. In experiment 2, two herbicides diclofop-methyl or pendimethalin were applied as postemergence treatment. The herbicide diclofop-methyl achieved an effective control of Italian ryegrass associated with barley even at rates as low as 0.25 kg/ha. Mean of ryegrass numbers and fresh weight (20 plants)/pot were decreased significantly and only few plants of L. multifloruim survived at 1 kg/ha, however, they were very small in size and badly damaged. Barley plants were not damaged by diclofop-methyl treatments at all applied doses. Pendimethalin created a significant effect (P=0.05) on ryegrass numbers/pot or fresh weight (20 plants/pot) at doses, 0.125 or 0.25 kg/ha. However, at 1 kg/ha there was about 40% reduction in weed numbers/pot and its fresh weight (20 plants/pot), which indicate low control effect of this chemical. There was no evidence of damage to barley plants by pendimethalin at all tested rates.