|Mccreight, James - Jim|
Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/3/2004
Publication Date: 6/1/2005
Citation: Mccreight, J.D., Matheron, M., Tickes, B., Platts, B. 2005. Fusarium wilt race 1 on lettuce. HortScience. 40:529-531. Interpretive Summary: Fusarium root rot of lettuce, known in Japan since 1955, has become a serious disease in Arizona and may become more serious in California. Fusarium root rot first affected commercial U.S. lettuce production in 1990 in Huron, Calif., but did not become a serious problem in the U.S. until 2001 when it appeared in the Yuma, Arizona lettuce production area and reappeared in Huron. The disease is also present in Pajaro Valley, Calif., which is close to the Salinas Valley, the major area of summer lettuce production in the U.S. Three races of Fusarium oxysporum f.sp. lactucae, the fungus that causes Fusarium root rot have been described in Japan. This research confirmed resistance in the major U.S. iceberg lettuce cultivar Salinas to race 1. Furthermore, the resistance in 'Salinas' is conferred by one or more recessive genes.
Technical Abstract: Three races of Fusarium oxysporum f.sp. lactucae, cause of Fusarium root rot of lettuce, are known in Japan, where the pathogen was first observed in 1955. Fusarium root rot first affected commercial U.S. lettuce production in 1990 in Huron, Calif., but did not become a serious problem in the U.S. until 2001 when it reappeared in Huron and appeared in the Yuma, Arizona lettuce production area. Reactions of three Fusarium root rot differentials ('Patriot', susceptible to races 1, 2 and 3; 'Costa Rica No. 4', resistant to race 1, and susceptible to races 2 and 3; and 'Banchu Red Fire', susceptible to races 1 and 3, and resistant to race 2) in a naturally-infected commercial field test and artificially-inoculated greenhouse tests, indicated presence of race 1 in the Yuma lettuce production area. Reactions of these differentials to an isolate from Huron confirmed the presence of race 1 in that area. Consistent with previous results from the U.S. and Japan, 'Salinas' and 'Salinas 88' were resistant to the Yuma and Huron isolates of race 1, whereas 'Vanguard' was highly susceptible. Limited F1 and F2 data indicate that resistance to race 1 in 'Costa Rica No. 4' and 'Salinas' is recessive. 'Calmar' is the likely source of resistance in 'Salinas' and 'Salinas 88'.