Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 7/2/1999
Publication Date: N/A
Technical Abstract: Collard and kale cropped during the summer may be infected by Fusarium oxysporum f.sp. conglutinans. Seedlings were root-dipped in 10 million microconidia/ml and grown at 25/25 or 30/25 degrees C day/night temperatures. In another test, seedlings were transplanted into naturally-infested sandy soil in Lexington County, SC, in June 1997 and 1998. Symptoms were rated visually five times in the growth chamber and three times in the field. Yellows were more severe at 30 than at 25 degrees C, but there was no cultivar-by-temperature interaction. Based on final disease incidence (DI) in the field, all five kale and seven of 17 collard lines were more susceptible (P=0.01) than Bravo cabbage, which has well-characterized resistance. DI was 73 to 21% for susceptible lines, 19 to 5.6% for resistant lines, and 4% for Bravo. Cultivar rating means from growth chamber and field experiments were highly correlated (P=0.0003), although Top Bunch collard was susceptible in the growth chamber, but was resistant in the field. Uncharacterized resistance to yellows in certain collard cultivars and landraces effectively decreased DI under disease-conducive conditions.