Monitoring for a new I3 resistance gene-breaking race of F. oxysporum f. sp. lycopersici (Fusarium wilt) in California processing tomatoes following recent widespread adoption of resistant (F3) cultivars: Challenges with race 3 and 4 differentiation methods

Peer-reviewed, open access. Sets out the race structure of Fusarium oxysporum f. sp. lycopersici on tomato as a ladder in which each race is named for the resistance gene it defeats: race 1 answered by I-1, race 2 breaking I-1 and answered by I-2, race 3 breaking I-2 and answered by I-3. Also the reason a fourth race is not declared here: the survey looked for an I-3-breaking race across 17 California fields over five seasons and never found one, having projected it would have appeared by now.