Submitted to: American Phytopathology Society
Publication Type: Abstract Only
Publication Acceptance Date: May 10, 2010
Publication Date: August 7, 2010
Citation: Larkin, R.P., Honeycutt, C.W., Olanya, O.M. 2010. Management of Verticillium wilt with disease-suppressive crop rotations. American Phytopathology Society. 100:S67. Technical Abstract: The ability of potential disease-suppressive rotation crops to reduce potato disease problems and increase crop productivity in a field severely infested with Verticillium wilt was evaluated over three field seasons in Maine. Disease-suppressive rotation treatments consisted of 1) a high glucosinolate mustard blend (‘Caliente 119’), a mixture of white mustard (Sinapis alba) and oriental mustard (Brassica juncea) known for its biofumigation potential, and 2) a sorghum-sudangrass hybrid, both grown as green manures. These rotations were compared with a standard barley rotation and a barley rotation followed by chemical fumigation with Metham sodium as controls. Both green manure rotations significantly reduced wilt in the subsequent potato crop compared to the barley control, with average reductions of 25 and 18%, respectively, but were not comparable to chemical fumigation (35% reduction). In addition, Mustard blend reduced other soilborne diseases (black scurf and common scab) to a greater extent than all other rotations, including chemical fumigation. Mustard blend and chemical fumigation treatments increased tuber yield relative to the barley control and sudangrass treatments by 12 and 18%, respectively. However, by the second rotation cycle (second potato crop after initial rotations), disease levels were high in all rotations, and only chemical fumigation resulted in substantial disease reduction (35%). Rotations also had significant effects on soil microbiology and pathogen inoculum levels. This research indicates the potential for using disease-suppressive rotations for managing Verticillium wilt and other soilborne diseases, but also demonstrates the limitations of 2-yr rotations regarding the build-up of soilborne diseases over time.