Arkansas Rice Update 6-7-24

by Jarrod Hardke, Rice Extension Agronomist - June 7, 2024

Arkansas Rice Update 2024-10

June 7, 2024

Jarrod Hardke and Camila Nicolli

“Breathe in, breathe out, move on.”

A Favorable Forecast You Say?

It’s been too long.  I don’t want to get ahead of myself, but the upcoming forecast may be the best things have looked since the third week of April.

Rice development has been rapid, with plenty of fields reaching reproductive growth (and well beyond) already here the first week of June.  While that progress is excellent to set us up for overall yield potential, it’s not without its limitations.  We’re up against herbicide cut-off situations in many fields where some clean up applications may be warranted.  Well, you’re going to have to live with some weeds it looks like.  See more on cut-off timings in the update.

While the past six weeks have been a struggle bus, the overall crop really does look good at this point.  The hard work to make things happen (nitrogen and herbicide applications) is clearly paying off.

With reproductive growth getting moving, be prepared to see disease start to develop.  It’s early as far as the calendar goes, but on time for crop development. 

We may also begin to see some obvious signs of nutrient deficiency around this time as the plant goes reproductive.  In some cases, remember that what may appear to be a deficiency may just be transient and part of the nutrient balance shift in the plant as it enters reproductive growth.  It is not uncommon to see plants become lighter green for a short time after joints begin to move – don’t overreact but give it time to see if it corrects itself before you consider any action.

Let us know if we can help.

Fig. 1.  NOAA 7-day precipitation forecast.

New on Arkansas Row Crops Radio:

Weeds AR Wild Series, S4 Ep 7:  Bottom of the 4^th Rain Delay

Fig. 2.  Fish in a rice field where a river backed out into the field.

Ricing Around

Jarrod Hardke

• Midseason nitrogen timing – for those growing varieties (e.g., CLL16, CLL18, DG263L, Diamond, Ozark, Taurus, etc.) – our recommended timing for midseason nitrogen has changed in recent years. We’re now less focused on growth stage and more focused on time after the preflood N was incorporated into the soil.

  • We now rely more heavily on preflood N than ever before. With these higher rates preflood, we need to be certain varieties have completed uptake of preflood N before we consider applying more at midseason.

  • We recommend waiting 4 weeks after preflood N was incorporated by flood before applying midseason N. Maximum uptake of preflood N occurs within 3-4 weeks of incorporation, and once we have reached this timing AND we’re at beginning internode elongation (BIE; green ring) we can apply midseason N and be assured we get maximum uptake and use out of that application.  If we apply midseason N too early – we risk the plant not being ready to take it up and not getting the full benefit.

  • This timing will be increasingly important this season as many preflood N applications have been delayed due to weather. Meaning we’re reaching BIE within a couple weeks after preflood N application.  Applying midseason N this early has the potential to result in no measurable benefit from the midseason N application.

  • These situations where BIE occurred shortly after preflood N application occurred as part of our midseason N studies and strongly support this recommendation of waiting 4 weeks.

  • DO NOT apply midseason N until after green ring AND 4 weeks after preflood N incorporation.

  • Remember, we don’t recommend a true midseason on hybrid rice – the comments above apply to pureline varieties. We’ll address the recommended late boot N application for hybrids in a later update.

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).

• Just treat the seed! Rice planted in Fig. 4 did not receive a seed treatment of any kind.  The seed ended up planted a little deep after heavy rains, so it struggled to emerge from the greater depth and had to deal with seedling disease pressure, before ultimately having severe stand loss in areas from grape colaspis feeding on roots.  A fungicide and insecticide seed treatment package could have helped prevent much of this situation.  Given the deeper seed depth, the addition of a gibberellic acid seed treatment would have also aided emergence and stand.

 Fig. 4.  Grape colaspis pruning rice roots and creating a “bean row effect”.

Herbicide Cut-Off Timings

Jarrod Hardke

Surprise!  Rice is hitting reproductive growth stages very quickly this season following above average temperatures over the past two months.  Notice in the table below that many herbicides have a cut-off timing just prior to or at beginning internode elongation (BIE; green ring).  Serious injury and crop loss may occur if these cut-off timings aren’t followed.

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.

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

Fig. 5.  Ricestar application onto rice at green ring.

First Reports of Rice Blast in Cross and Randolph Counties

Camila Nicolli

Rice leaf blast was reported from isolated field spots in Cross and Randolph Counties this week.  Blast can lead to significant yield losses if not managed effectively. 

Key symptoms to watch for include small, diamond-shaped lesions with gray centers and brown margins.  Early symptoms may appear as grayish-black spots.  Typical blast symptoms can be found by opening the canopy to inspect lower leaves.

Clearly it’s time to begin scouting for leaf blast, especially in any fields with a history of blast or with conditions that favor the disease (low-lying areas, surrounded by tree lines, susceptible cultivars).  We typically receive our first reports of blast around the third week of June.  Recent conditions and early rice development are fueling the early start.

Focus scouting efforts on tree lines, dry field edges, levees, and areas with greener, denser canopies due to excess nitrogen fertilization and double drilling.

For leaf blast, we do not recommend treating unless it begins to burn down areas of the field.  Rather, increase flood depth (4-inch water depth) to suppress disease development at this time.  At heading, a fungicide application may be considered for prevention of neck and panicle blast.  Please send additional reports of leaf blast finds our way so that we can collect samples and continue to monitor this disease.

Fig. 6.  Rice leaf blast showing up as rice moves into reproductive growth.

CBOT September Rice Futures, 10-Year Monthly Continuation.

DD50 Rice Management Program is Live

The DD50 Rice Management Program is live and ready for fields to be enrolled for the 2024 season.  All log-in and producer information has been retained from the 2023 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.