Weed management is an important component in sustainable agriculture. The current agriculture is changing with climate change. Allelopathy has been recognized as a component of integrated weed management over the years. The allelopathic ideas have been used in various facets of allelopathic implications. Some of these include use of cover crops, plant residues, plant extracts, crop cultivars and others. And it is being challenged under climate change factors such as increased atmospheric CO2, temperature rise, erratic rainfall patterns and others. The relevance of allelopathy has been highly discussed due to the lack of phytotoxic concentrations of allelochemicals under field conditions. Crop residues from existing crop or rotational crops can provide selective weed suppression through their physical presence on the soil surface and/or through the release of allelochemicals. Brassica nigra, Avena fatua, Fagopyrum esculentum, Secale cereale, Sorghum bicolor, Triticum aestivum and other cover crops have been used in weed management on a limited basis. Some of the allelochemicals such as DIBOA, DIBOA-glycoside, dhurrin, isoflavonoids, isothiocyanate, juglone, momilactone, scopoletin, and sorgoleone have been reported to play a role in weed management under field conditions. The living and dynamic soil system influences the fate and functions of allelochemical activity. The bioavailability of allelochemicals in the soil is dependent on soil processes such as adsorption, leaching and degradation by abiotic and biotic factors. These processes and other related soil conditions are greatly influenced by several underlined climatic variables. Future allelopathic research should be focused on persistence and availability of allelochemicals in soil environment. The bioavailability of allelochemicals under field conditions with climate change associated rising atmospheric CO2, rising temperature and intensity and erratic rainfall must be established for its effective practical role in weed management. Currently, we face challenges and opportunities in using allelopathy as a part of weed management strategies in today’s agriculture.