Parthenium weed (Parthenium hysterophorus L.) is a weed of a national significance in Pakistan. Although, Parthenium weed is infesting many parts of Khyber Pakhtunkhwa province but more affected regions are Peshawar valley and Hazara division where it has enormously invaded most of the open spaces like roadsides, wasteland and water ways resulting in loss of local biodiversity. To manage this weed, comprehensive studies including field survey, laboratory and field experiments were carried out from 2013-14 in both Pakistan and Australia. First of all field survey of two Districts Swabi (Peshawar Valley) and Haripur (Hazara Division) of Khyber Pakhtunkhwa, was carried out during May-June, 2013-14 to study the distribution of Parthenium weed. Five villages were selected from each district and thirty locations were randomly selected. The data revealed that the flora is predominated by Parthenium with the highest relative density of 63.4% among all weeds, followed by Cynodon dactylon L., Cannabis sativa L. and Chenopodium album L. with relative density of 11.37%, 10.86% and 7.31% respectively. Moreover, at different location the Parthenium weed is competing with C. sativa which is not a problematic like Parthenium weed and replaced by the latter. Mean distribution of Parthenium weed infestation was abundant and all sites are not uniform, because some sites were in hilly area. The computed data showed that the highest relative frequency of 28.71% was recorded for Parthenium weed followed by C. sativa, C. dactylon and C. album having relative frequency of 13.33%, 12.71% and 10.16%, respectively. Comparatively, the other weeds were very low relative density and relative frequency at most of the locations studied. Importance value shows that P. hysterophorus, C. sativa, C. dactylon and C. album were predominant weeds in both Districts. Parthenium- Cannabis- Cynodon communities predominated the weed flora in Swabi and Haripur Districts of Khyber Pakhtunkhwa. Laboratory trials were carried out with the aim to suppress the seed germination and seedling growth of invasive weed P. hysterophorus with the water extracts of different plant species. The tested plant species comprised of Zea mays L., Sorghum bicolor (L.) Moench, Cenchrus ciliaris L., Panicum miliaceum L., Vigna radiata (L.) R. Wilczek and Vigna aconitifolia (Jacq.) Marechal. The statistical analysis of the data revealed that the poaceous crops viz. Z. mays and S. bicolor seriously affect the seed germination and seedling growth of P. hysterophorus by giving only 39.50 % and 45.50 % seed germination respectively, as compared to control where 100% germination was recorded. Moreover, the P. hysterophorus showed much tolerance towards the water extracts of both the legume crops V. radiata and V. aconitifolia that gave almost at par results with the control treatments for all the examined parameters of P. hysterophorus. In addition, the water extracts of C. ciliaris and P. americanum moderately affected the seed germination and seedling growth of P. hysterophorus during the investigations. Another field based studies were undertaken at two different locations having variable climatic conditions, to manage P. hysterophorus through some suppressive plants. The study revealed that the sorghum, bufell grass, millet and maize were emerged as good suppressive plants to the P. hysterophorus as compared to control and produced higher biomass in both the field sites. These plants reduced the P. hysterophorus growth up to 83.3%, 80.3%, 73.5% and 60.5%, respectively. Whereas, mungbean and moth bean were found poor suppressive species to P. hysterophorus. Moreover, the competitive ability of parthenium with other plants was climate dependent as this weed poorly competed with the tested plants in the warmer climatic condition at Swabi site than the cooler area at Haripur site. Thus, it is recommended that sorghum and buffel grass are the better option to manage the P. hysterophorus in the fields infested with invasive P. hysterophorus. Similarly, in Queensland, Australia field experiments were carried out at two different locations in Central Queensland, during October, 2011 to April, 2012. Field sites run at two climatically different locations (Injune, South Central Queensland and Mungallala, South West Queensland) to find out the suppressive ability of eleven test species against the growth of parthenium weed. Out of eleven species, seven were tested at Injune (buffel grass, butterfly pea, tall finger grass, whynn cassia, bumswich grass, red grass and paddock love grass) and at Mungallala (tall finger grass, queensland blue grass, rhodes grass, whynn cassia, bull mitchall grass, buffel grass and seca stylo). Out of seven species at Injune, only tall finger grass emerged strongly suppressive to Parthenium weed growth by >80% followed by butterfly pea (66 %), buffel grass (65 %) and wynn cassia (61 %), while the two native species red grass and paddock love grass were found weaker establish. At this site, the best fodder biomass was produced by buffel grass followed by butterfly pea, while bumswich grass showed moderately dry biomass and red grass found poor producing dry biomass in all selected species. Out of seven species tested at Mungallala, four (tall finger grass, ghodes grass, queensland blue grass and wynn cassia) were found to be strongly suppressive of the parthenium weed growth suppressing >80%, while queensland blue grass produced the highest dry biomass. The reduction of parthenium weed abundance has not yet translated into an improvement in pasture community species richness, which is expected to be detected in future years. This study demonstrates that parthenium weed can now be better managed, in a sustainable fashion, using valuable forage plants, in a wide range of habitats. Hence, it is suggested that suppressive species may be included as a biological control measure in long term parthenium management programs.