Arkansas Rice Update 6-16-23

by Jarrod Hardke, Rice Extension Agronomist - June 16, 2023

Arkansas Rice Update 2023-13

June 16, 2023

Jarrod Hardke, Trent Roberts, and Tommy Butts

“Good times, bad times, you know I’ve had my share.”

Finally, Some Relief

Widespread rainfall has been the talk of this week (Fig. 1).  Beginning last weekend and continuing scattered through this week, most got at least some of the help they were looking for while a few got a little more than they bargained for.  A shift to more humid, southerly winds has things feeling more like rice growing weather.

More rain is expected in the 7-day forecast (Fig. 2).  Most of that may occur on Saturday night into Sunday, but there are more small chances scattered later in the week.  With that, much of the originally forecast heat expected to be headed our way looks to be milder now.  Highs in the upper 80s appear likely, but with rice getting to midseason having warm, humid weather and scattered rain is a sheath blight recipe.  Be on the lookout but avoid making too early applications – we’ll cover more on this topic next week.

Travels around the state continue to indicate a good-looking crop.  There are problem fields for sure, but the majority of the rice is hitting its stride and moving along nicely.

Midseason nitrogen application timing is the major topic this week as we start getting to reproductive growth across many acres.  Progress!

Let us know if we can help.

Fig. 1.  Last 7-day observed precipitation 6-16-23 (NOAA-AHPS).

Fig. 2.  NOAA 7-day precipitation forecast.

New on Arkansas Row Crops Radio this week:

Weeds AR Wild Series, S3 Ep12:  Midseason Weed Control Topic Rundown

Green Ring Isn’t What It Used to Be

Jarrod Hardke and Trent Roberts

Midseason nitrogen (N) timing recommendations have evolved over the past few decades.  Twenty years ago, recommendations focused on applying midseason N between green ring and ½” internode elongation; or if two midseason applications are used, the first is made in the window mentioned and the second approximately 7 days later.  Evolution of new cultivars with enhanced management practices have led to new research and this is no longer the recommendation due to more recent data.

Fig. 3 shows a summary of midseason N response by days after preflood N incorporation.  It paints a nice picture of our recommended timing for midseason N:  wait until at least 4 weeks after preflood N is incorporated AND after green ring before applying midseason N.

Note that while some newer varieties such as DG263L and PVL03 have not been evaluated in this type of trial – we do know that they reach reproductive growth stages (green ring) very fast.  This means that applying midseason based off their growth stage could lead to a very early midseason N application that won’t realize its full potential.  Continue to wait the 4 weeks with these varieties as well.

The need to wait 4 weeks is to allow ample time for the rice to take up the preflood N.  Early application of midseason N, when the rice is still taking up the preflood reduces the effectiveness of both applications.  Imagine working on a nice ribeye steak and when you’re about ½ way through it someone throws down some bread pudding.  You aren’t going to say no, but you kind of want to finish the steak first.

Now there have been instances where the preflood N rate applied in commercial fields has been less than recommended or issues cause greater loss of the preflood N.  In these situations, it may be that the midseason N needs to be applied earlier if the rice is clearly showing signs of running short on N.  However, keep in mind that as rice shifts into the reproductive growth stages, there can be a slight paling as the plant begins to draw on and use more N.  This paling usually only lasts for a couple of days and is not cause for an early application.  Nitrogen is highly mobile in the plant and is stored in the leaves for the plant to draw from.

For those still kicking around the growth stage side of things, Fig. 4 is included which shows the same data from Fig. 3 but this time grouped by growth stage timing (0 = green ring, 7 = 1/2” internode elongation, etc.).  Here again, applications from green ring to ½” IE do not appear to be the most efficient, except where those timings coincided with at least 4 weeks since the preflood N was incorporated.

A final thought – these comments apply to pureline varieties.  We do not recommend midseason N on hybrids.  If a noticeable yield response is occurring from a midseason application to hybrids, then the preflood N rate is likely not high enough and should be increased in the future.  For hybrids we recommend the preflood application and a late boot application.  In rare situations where preflood N is lost there may be a need for midseason to replace the lost preflood N on hybrids, but otherwise is unnecessary.

We’ll cover more on the benefits of the late boot N for hybrids in the future.

Fig. 3.  Grain yield response from midseason nitrogen (N) application by days after preflood N incorporation across 60+ site-years from 2012-2018 (includes data from Taggart, Cheniere, CL152, Roy J, Mermentau, CL153, and Diamond).

Fig. 4.  Grain yield response from midseason nitrogen (N) application by growth stage (days after beginning internode elongation) across 60+ site-years from 2012-2018 (includes data from Taggart, Cheniere, CL152, Roy J, Mermentau, CL153, and Diamond).

Herbicide Max Use Rates and Cut-Off Timings

Tommy Butts

A large portion of the rice in the state is now reaching or already at flood and moving into reproductive growth stages.  As a result, it’s important to remember cut-off timings and season max use rates for herbicide applications.  Applications of herbicides above season use rates or occurring after cut-off dates can result in rice injury and yield loss.  Table 1 provides this information as a quick reference for postemergence rice herbicides.  For additional information regarding max season use rates and cut-off timings of other herbicides or for other cropping systems, check out the MP566 Application Cut-Off Timings for Common Herbicides and MP567 Max Use Rates per Application and per Season for Common Herbicides.  Good luck out there!

Table 1. Rice herbicide cut-off timings and season max use rates.

DD50 Rice Management Program is Live

The DD50 Rice Management Program is live and ready for fields to be enrolled for the 2023 season.  All log-in and producer information has been retained from the 2022 season, so if you used the program last year you can log in just as you did last year.  Log in and enroll fields here:  https://dd50.uada.edu.

Use the Arkansas Rice Advisor Internet App!

The Arkansas Rice Advisor site https://riceadvisor.uada.edu functions like an app on your mobile device.  There you can readily access the DD50 program, rice seeding rate calculator, drill calibration, fertilizer and N rate calculators, publications, and more.

Additional Information

Arkansas Rice Updates are published periodically to provide timely information and recommendations for rice production in Arkansas.  If you would like to be added to this email list, please send your request to rice@uada.edu.

This information will also be posted to the Arkansas Row Crops blog (http://www.arkansas-crops.com/) where additional information from Extension specialists can be found.

More information on rice production, including access to all publications and reports, can be found at http://www.uaex.uada.edu/rice.

Acknowledgements

We sincerely appreciate the support for this publication provided by the rice farmers of Arkansas and administered by the Arkansas Rice Research and Promotion Board.

The authors greatly appreciate the feedback and contributions of all growers, county agents, consultants, and rice industry stakeholders.