Parthenium hysterophorus, commonly known as parthenium weed, is an invasive
alien species in Pakistan. There are no specialized natural enemies native to
Pakistan that attack the plant species inflicting serious damage and, thereby,
keeping it under control. The rust species Puccinia abrupta var. partheniicola,
commonly known as the winter rust, is closely associated with its host parthenium
weed in its native range in the Americas. This study reports on the first record of
the winter rust in Pakistan, with a likely pathway of introduction via India or Nepal. Puccina abrupta var. partheniicola was found to be widely present in several districts of the Punjab and Khyber Pakhtunkhwa Provinces. The sites where the most severe infestations of parthenium weed were observed were in the Lahore District of the Punjab Province. The climatic conditions prevalent in this region during the winter season 2018/2019 were favourable for the winter rust and caused an epiphytotic on parthenium weed. The presence of P. abrupta var. partheniicola marks the second natural enemy of P. hysterophorus recorded from Pakistan and is expected to aid the management of this invasive weed in the country.