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Managing Stewart's Wilt with Seed Treatments and Variety Selection 2000

 

Project Leaders: Lee Stivers, NYCRF; Tom Kuhar, Entomology Dept.; Al Taylor, Hort. Sci.; and Mike Hoffmann, Entomology Dept.

Abstract:

A combination of on-farm, laboratory, and field experiments were conducted to determine efficacy and potential phytotoxicity of insecticide seed treatments for several sweet corn varieties ranging in resistance to Stewart’s wilt disease. In ‘Sprint’, a susceptible variety, seed insecticide treatments (Gaucho or Adage) reduced incidence of Stewart’s wilt Å 68 to 83% compared with the non-treated control. Severity of symptoms differed primarily with variety rather than seed treatment. On-farm monitoring of five pairs of fields planted to a susceptible variety, with or without Gaucho seed treatment, confirmed the efficacy of seed treatment; disease incidence averaged 2.5% in treated versus 20.8% in non-treated fields. Germination tests of aged and non-aged seed lots treated with Gaucho were performed. Gaucho reduced 4-day germination in ‘Sprint’, but not in ‘Dynamo’ and ‘Bonus’. Overall, aging decreased both 4-day and final germination compared to non-aged treatments. Aging plus Gaucho treatment further reduced emergence for ‘Sprint’ and ‘Dynamo’, but not ‘Bonus’. Varietal resistance continues to be the most important factor in controlling Stewart’s wilt in sweet corn. For varieties that have little resistance, or for protecting all varieties against early infection, Gaucho seed treatment is another effective management tool. However, seed treated with Gaucho should not be carried over to the following year, especially for weaker seed lots.