Dickinson Research Extension Center ~ 1089 State Avenue, Dickinson, ND 58601

Ashley, R.O. E.D. Eriksmoen, and M. B. Whitney. 2002. Sunflower date of planting study in western North Dakota - 3-year summary [Online]. National Sunflower Association 2002 Research Forum Proceedings, 17-18 Jan 2002, Fargo, ND.

Web link (http://www.sunflowernsa.com/research_statistics) August 20, 2002)

Sunflower is considered a late season crop in much of North Dakota with plantings occurring as late as the last half of June. The objective of the project was to determine and demonstrate the optimum planting date of NuSun sunflower varieties for southwest North Dakota. Achene yield was significantly higher for 23 May plantings when compared to late April plantings for all three years of the study. Oil yield was greatest for the 23 May plantings in two of the three years that this study was conducted. Oleic content of the oil produced was greatest for the 23 May plantings with lowest oleic content occurring in mid to late June plantings.

Slack, D.C., E.C. Martin, A.E. Sheta, F. Fox, Jr., L.J. Clark, and R.O. Ashley. 1996. Crop coefficients normalized for climatic variability with growing-degree days. In Proceedings of the International Conference on Evapotranspiration and Irrigation Scheduling ASAE. San Antonio, TX. Nov 3-6, 1996.

Crop coefficients relate the phonological development of a particular crop to evapotranspiration. Phenological development of many plants has been show to be a strong function of accumulated heat units or "growing-degree-days" (GDD). Such information has been used to effectively predict harvest dates for process vegetables and melons and to accurately predict maturity of a number of field crops. We have developed growing-degree -day based crop coefficients for twenty-three (23) field, forage, vegetable, and vine crops from field experiments and a variety of data sources in the literature. The crop coefficients presented were developed to be utilized with a computerized irrigation scheduling program (AZSCHED) which was developed to be compatible with the Arizona Meteorological Network (AZMET). Complete descriptive numerical information is provided for crop coefficient curses for potatoes and tomatoes as well as cotton and cantaloupe.