By Jarrod Hardke, Rice Extension Agronomist
Each year I’m surprised at the number of producers not currently using the DD50 Rice Management Program on their farms. This program is designed to take much of the guesswork out of in-season management for producers and consultants. In general, projected dates of key timings are accurate within a couple of days throughout the season. Keep in mind that a good emergence date is critical to an accurate DD50 report – when the majority of plants are spiking (even if they’re still white) is the accurate date (Fig. 1).
Arguably the most useful components of the program are the nitrogen (N) application timings. The early and final recommended times to apply N are key to maximizing grain yield potential. Numerous studies over the years have shown the benefits of N applied during this window and the yield penalty associated with later applications after the final recommended date. Remember that the goal is have N incorporated by the final date, though there are a few days built in to allow for flood-up time.
Many herbicides have cutoff timings around beginning internode elongation (BIE / green ring) or 1/2-inch internode elongation (1/2” IE). The most commonly used of these herbicides are all included in the DD50 printout allowing you to plan for applications prior to cutoff to minimize the chance for crop injury issues. For midseason N applications for varieties we want to be sure we’re at least past green ring AND at least 4 weeks after preflood N was incorporated.
Approximate heading dates are key to knowing when fungicide applications should go out (if needed). This also sets us up to begin scouting for rice stink bug and making any needed insecticide applications.
The approximate time of 20% grain moisture (maturity) is the most fluid date in the printout, because 50% heading is the last date that can be predicted based on DD50 units. So the date of maturity can be influenced by not just temperature but also light and moisture (rainfall and dew). However, knowing these dates gives us an idea of how to prioritize fields and cultivars for harvest.
Every cultivar is different in terms of how it reaches key growth stage timings including green ring, 1/2” IE, and 50% heading. Individual reports for different cultivars at different planting dates will help us to more easily manage each cultivar at each planting date to its maximum potential. Each year the answer to why many fields underperform often relates back to management activities occurring too late to maximize their benefit.
As we (unfortunately) have some time right now due to continued rain, take a few minutes to familiarize yourself with the improved DD50 program so you’re ready to use it in 2020. Setting up your account only takes a few minutes and then you’ll be ready to put it to work when the season gets rolling and fields can be entered after emergence (spiking).
Access the program at https://DD50.uaex.edu. You can also access it through the Rice Advisor online app https://riceadvisor.uaex.edu along with many other calculators and rice production information. All of this content is mobile friendly and works well on all devices. Prior to the start of the season, we hope to roll out the ability to opt-in to receive text messages when fields in DD50 near important dates such as final N timing, green ring, etc. If you have questions or need help, contact your local county Extension office or me directly at firstname.lastname@example.org.
The DD50 Rice Management Program is made possible by support from Arkansas rice growers through the Rice Check-Off administered by the Arkansas Rice Research & Promotion Board and support from the University of Arkansas System Division of Agriculture.