Late Planted Sunflower Performance In Eastern North Dakota.

Information on crop performance from late seeding dates is important for producers when field conditions prevent timely planting and also when stand establishment problems occur that prompt replanting decisions. A late sunflower seeding date study was conducted near Prosper, ND, during the 2009 and 2010 seasons with two early maturity oilseed hybrids. The experiment was a RCBD in a split plot arrangement with seeding date the main plot and hybrid the subplot. Seeding dates began about 25 June and continued for a total of six weekly dates during both years. Plots consisted of three rows spaced 60 cm and 7.6 m in length. Stands were oversown and thinned at the V2 to V4 stage to 54,340 plants per hectare. Traits evaluated were flowering, plant height, root lodging, stalk lodging caused from white mold, seed shatter, seed yield, and seed weight and oil content. Yield was often similar from the first two or three seeding dates and then decreased at later dates. Seed yield decreased 32% (Date 3) and 50% (Date 4) in 2009 and 2010, respectively, when compared to Date 1 for Hybrid 8N272. Seed yield decreased 70% (Date 4) and 80% (Date 5) in 2009 and 2010, respectively, when compared to Date 1 for Hybrid 803. Seed oil content followed the same general decrease as seed yield for the hybrids. Seed yield and oil content were good for both hybrids from the first two seeding dates in 2009 (1,800 to 2320 kg/ha, 430 to 464 g/kg) and the first three seeding dates in 2010 (1,755 to 2,400 kg/ha, 444 to 493 g/kg). Based on these results seeding before the second week in July would give good crop performance.