Most onion growers are not strangers to thrips, the vectors for Iris Yellow Spot Virus; the presence particularly has been noticeable in the western United States. Findings from Colorado State University Extension, for example, note the presence of Iris Yellow Spot Virus beginning back in September 2001. Onion fields, in particular, have been monitored by CSU since 2002, with the CSU advising growers to practice tougher pest management.
The focus on increasing onion plant vigor is one way that growers such as Schnorr Farms, located near Fort Collins, Colorado, have built disease resistance within their onions. Passed on from grandfather to father, and now to son, Chris Schnorr, the family-run farm consists of 2,000 acres, including corn, sugar beets, alfalfa and wheat, as well as 100 acres of Foliar TRIGGRR®-treated onions.