Beware of giant hogweed, officials say as battle to kill dangerous weed drags on

One of Ontario's most dangerous invasive weeds is spreading across southwestern Ontario, prompting a warning from a local conservation authority and extending an on-the-ground battle to destroy it.

The Upper Thames River Conservation Authority (UTRCA) said it's spent more than 120 hours so far this year fighting the spread of giant hogweed — a large invasive plant that has a sap known to cause reactions ranging from mild to severe.

"It ranges from a mild rash on your skin to heavy purple blotches and really severe blistering. In the most severe cases we've heard about ... it can cause temporary blindness," said Brandon Williamson, the land management coordinator for the UTRCA.

Officials have been patrolling the upper Thames watershed, looking for the telltale signs of the dangerous weed