Chemical Control Against Aggressive Broad Leaves Weed Ipomea sp. in Drill Seeded-rice (Oryza sativa L.)

Two field experiments were carried out at the Experimental Farm of Rice Department, Sakha Agricultural Research Station, Kafrelsheikh, Egypt throughout 2020 and 2021 summer seasons to identify an efficient chemical control program against Ipomea sp. as perennial Convolvulaceae weed in drill seeded-rice. The experimental design was split-plot with three replications. Three times of herbicidal application at 20, 30 and 40 days after sowing (DAS) were allocated randomly in main plots, while in sub-plots, six weed control treatments were randomly distributed included three single herbicides application (bentazone at rate of 1.714 kg ai ha-1, fluroxypyr at rate of 0.0952 kg ai ha-1 and bensulfuron-methyl at rate of 0.0714 kg ai ha-1) in addition to two herbicide mixtures were bentazone + fluroxypyr (1.344 kg ai ha-1 + 0.0952 kg ai ha-1) and bensulfuron + fluroxypyr (0.0714 kg ai ha-1 + 0.0952 kg ai ha-1) as compared to un-treated (weedy check) plots. Chemical control at early stage (20 DAS) achieved the best Ipomea control and recorded the lowest values of tillers number m-2, fresh and dry weights during 2020 and 2021, consequently recorded the highest rice dry matter, panicles number m-2, panicle weight and grain yield during both seasons. The results also showed that herbicide mixtures exceeded single application of herbicide in controlling Ipomea as broad leaf weed, bentazon + fluroxypyr ranked first in weed control efficiency percentage and recorded the lowest weed density m-2, fresh and dry weights of Ipomea during the two seasons of study as well as achieved the best values in rice dry matter, panicles per square meter, panicle weight and grain yield during 2020 and 2021 seasons, while the mixture of bensulfuron + fluroxypyr ranked second in this respect. The combination of bentazone + fluroxypyr sprayed at 20 DAS recorded the best Ipomea chemical control efficiency (95.4 %) and recorded the best rice grain yield (9.322 t ha-1) as an average for Giza 178 cv under drill seeded-rice conditions.