Chemical control of Parthenium hysterophorus L. at different growth stages in non-cropped area

Parthenium hysterophorus L., is a noxious annual weed rapidly spreading across the non-cropped areas of the Khyber Pakhtunkhwa (KP) province and elsewhere in Pakistan. Parthenium weed has attained the status of most frequently and densely occurring weed in Swabi, Mardan and Charsadda districts while it is present in Peshawar district in isolated infestations. Parthenium weed has become a major threat to grazing land, roadside, wasteland, wetland, as well as cultivated land in KP province. Field experiments were conducted to evaluate the efficacy of different herbicides against parthenium weed at different growth stages in non-cropped area of Charsadda District, KP-Pakistan during summer 2009 and 2010. The experiments were laid out in RCBD, replicated four times separately for each growth stage with ten treatments. Herbicides used in the experiments were Aatrax (atrazine) @ 1.0, Buctril Super 60 EC (bromoxynil+MCPA) @ 0.80, Round Up (glyphosate) @ 4.0, Dual Gold 960 EC (S-metolachlor) @ 1.92, 2,4-D @ 1.0, Sencor Extra (metribuzin) @ 2.0, Logran Extra 750 WG (triasulfuron + terbutryn) @ 0.30, Primextra Gold 720 SC (atrazine+s-metolachlor) @ 1.50 Stomp 330 EC (pendimethethalin) @ 1.50 kg a.i. per ha and a control. Statistical analysis of the data showed that different herbicidal treatments had significant effect on parthenium weed mortality. At rosette stage of parthenium weed herbicides treatments provided (32.5 to 89%) mortality at 2 weeks after treatment (WAT) and (42.5 to 96%) mortality at 4 WAT. Maximum parthenium weed mortality 96% and 87% were recorded in glyphosate and metribuzin treatments at 4 WAT at rosette stage. While 2,4-D, triasulfuron+terbutryn, bromoxynil + MCPA and atrazine+s-metolachlor gave 71-80% control of rosette parthenium weed at 4 WAT. The parthenium weed mortality of atrazine and s-metolachor were 56.5% and 57.5%. At bolting stage, herbicidal application gave 35-83.5% control at 2 WAT and 30-91% mortality at 4 WAT. The most effective treatments for parthenium weed control were glyphosate and metribuzin having 91% and 75% mortality at 4 WAT. While triasulfuron+terbutryn, bromoxynil+ MCPA and atrazine+s-metolachlor gave 50-61.5% control at 4 WAT. Weed mortality with atrazine, s-metolachlor and 2,4-D was 36.5, 41 and 43%, respectively. Pendimethalin was the least effective treatment for both growth stages. Overall, the efficacy of herbicides was promising on rosette parthenium plants than bolted plants.