Publications for:

pest = Lolium perenne perenne (weed)
crop = Barley (Hordeum vulgare)

found 2 publications:

2005

Early vigour and allelopathy - two useful traits for enhanced barley and wheat competitiveness against weeds
Weed Research (2005) 45 (2), 94-102
publishers website - pestinfo wiki

2004

Variation in allelopathic activity over 100 years of barley selection and breeding
Weed Research (2004) 44 (2), 78-86
publishers website - pestinfo wiki