The proposed W4008 project builds on highly successful preceding multistate onion projects (W1008: Biology and Management of Iris yellow spot virus (IYSV) and Thrips in Onions, from 2005-2010; W2008: Biology and Management of Iris yellow spot virus (IYSV), Other Diseases and Thrips in Onions, from 2011-2016; and W3008: Integrated Onion Pest and Disease Management, from 2017 to 2022). The most significant change to our proposed multistate project is that we will include a weed biology and management objective. Similar networking successes are anticipated for weed scientists working in onion cropping systems across the country, just as they have occurred with entomologists and plant pathologists during our previous multistate projects.