Greenhouse Screening of Cotton Varieties Against Fusarium Wilt Complex

Fusarium oxysporum f. sp. vasinfectum race 1 and 2 (FOV) and the Meloidogyne incognita (southern root-knot nematode, RKN) complex can cause severe losses in cotton, and management recommendations include using varieties that are resistant to RKN. The objective of this project was to test the response of different varieties to the Fusarium wilt complex with and without RKN resistance. Four greenhouse trials were conducted, where cultivars infested with RKN and FOV were evaluated on (i) leaf wilt symptoms rated every 3 to 4 days to calculate the area under disease progress curve (AUDPC) and (ii) visual ratings of root and stem necrosis at the end of each trial. RKN-resistant cultivars PHY 480 W3FE and DP 1747NR B2XF had statistically similar AUDPC, root necrosis, and stem necrosis as RKN-susceptible cultivars DP 1522 B2XF and DP 1646 B2XF in all trials. This demonstrated that RKN resistance does not correlate to FOV resistance, and RKN resistance alone is not sufficient to manage Fusarium wilt. Cultivar ST 4946GLB2, which carries both RKN and FOV resistance, statistically had the lowest AUDPC, root necrosis, and stem necrosis in all greenhouse trials.