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22
Aug
2014
Arkansas Rice Update 8-22-14
Author: Jarrod Hardke, Rice Extension Agronomist

August 22, 2014                         No. 2014-24

Dr. Jarrod Hardke, Dr. Gus Lorenz, and Dr. Yeshi Wamishe

Crop Progress

The heat is finally here.  And so is the humidity.  Fields that have been drained and are waiting on harvest are having a hard time dropping in moisture.  A few fields are actively being harvested, but it’s slow going.  Things should really kick off to start next week with the big push on the way as we hit September.

Current conditions are very favorable for rice development and for maximizing heat unit accumulation.  Daytime highs and overnight lows are just right for crop progress and are low enough to avoid plant stress that might affect yield and grain quality.  Next week has a few days of rain chances but high temps will still be in the low 90s.  Hopefully drier air will follow the rain to help the drying process.

DD50 predictions a look a little off?  Comparing DD50 projections to our planting date studies this year it looks like March planted rice is 4-7 days behind the DD50 prediction, April planted rice is 3-4 days behind, and May rice is 0-3 days behind.  Keep in mind that some of the cultivars included in the DD50 program only have a couple of years of data since their release and have a greater potential for projections being shifted.

The main purpose of pointing that out is to point at Table 1.  Not quite 20% of fields are at harvest maturity (20% grain moisture) but we’re not that far off.  The numbers in the table are probably early by about a week, meaning the largest percentage of acreage will begin reaching harvest levels the first week of September.

Table 1.  Percent of rice acres set to reach harvest moisture during listed weeks of 2014 according to DD50 enrollment.

2014-24 Table 1

Out Standing in Your Field

Picture 1. Levee gates are starting to be pulled on a regular basis.

Picture 1. Levee gates are starting to be pulled on a regular basis.

Draining

Deciding when to drain a field continues to be one of the most difficult decisions involved in rice production.  The standard recommendation is to drain long-grain cultivars 25 days after the field reached 50% heading; and for medium-grain cultivars 30 days after 50% heading.  Grain progress can also be used to supplement drain timing decisions depending on soil type.  Silt loam soils that will dry out faster will typically benefit from maintaining a flood until over 1/2 to 2/3 of kernels on panicles are straw-colored.  On clay soils that will take longer to dry out, fields can be drained earlier as panicles approach having 1/2 of kernels straw-colored.  If you have a field that you know takes a really long time to get drained and dried out, you may pull the gates a little sooner.  Similarly, if you have a field that you know you can get the water off of fast and it will dry on out, you may hold the water a little longer.

A few dollars per acre in added pumping costs may be worth more than you realize.  To try some fuzzy math, let’s say there are 40 panicles per square foot in your field.  If you dry too early and don’t fill 5 kernels on every panicle, then you’re looking at a possible loss of 10 bushels per acre.  It’s still not that simple, with the weather impacting our ability to get in the field to harvest efficiently and without rutting it up and causing more problems, but these are all things that need to be considered.

Salt, Salt, Salt

As some of the fields that have been drained refuse to dry down with high humidity and heavy dew, some are starting to consider the use of sodium chlorate to desiccate those fields.  Remember that sodium chlorate is a tool – it can help when used properly, but it can hurt when used improperly.  Sodium chlorate should only be applied once grain moisture falls below 25%.  Do not apply if grain moisture is below 18%.  Once an application is made and foliage begins to dry out, so do the grains.  Up to 5% grain moisture reduction can occur in just a few days after application – so be ready to harvest 4-7 days after application.  In a year like this where many fields are experiencing uneven heading, grain moisture content may vary widely from one panicle to the next – this makes applying sodium chlorate a very risky proposition because many panicles may be at a high moisture and grain fill incomplete.  Use caution when considering the use of harvest aids – we don’t want to lose any of the crop we had a difficult year making.

Insects

Occasional blank panicles are showing up this time of year as usual.  While some are due to disease, others are due to the rice stalk borer (Picture 2, 3) and some from rice billbug as mentioned in a previous update.  In general these only show up as scattered heads and are more of an aggravation.  However, let us know if you find an area that seems to have an unusually high number of heads affected – we’ll want to have a look.

Rice stink bug has gone off the radar of late.  Extremely low numbers being reported, but don’t stop scouting, especially in fields that will be heading late.  If you have a field that’s one of the last to heading in a given area, it may be just the meal they’re looking for.  They’re strong fliers so they can quickly move to favorable fields from surrounding areas.

Picture 2. Rice stalk borer larva in a stem.

Picture 2. Rice stalk borer larva in a stem.

Picture 3. Whiteheads (blank panicles) due to rice stalk borer.

Picture 3. Whiteheads (blank panicles) due to rice stalk borer.

Disease

Fields that were treated with properly-timed fungicide applications for blast are showing the benefits of those applications.  Only a small percentage of panicles seemed to be affected by blast in those fields (Pictures 4, 5).  If you have late fields with blast concerns – keep an eye on them and be prepared to take action.  A deep flood helps a lot, but be prepared to break out the heavy artillery (fungicides).

Picture 4. Panicle blast dries out part or most of the panicle.  Once heads are out of the boot, fungicides are not effective.

Picture 4. Panicle blast dries out part or most of the panicle. Once heads are out of the boot, fungicides are not effective.

Picture 5. Neck blast rots the neck and the whole panicle dries out and breaks.

Picture 5. Neck blast rots the neck and the whole panicle dries out and breaks.

The variability in heading made smut prevention applications more difficult, and false smut is beginning to show up (Picture 6).  False smut spore galls replace the kernels.  High nitrogen rates in fields with a history will increase false smut.  Timely fungicide applications at boot suppress 50-75% of false smut.  After boot, fungicides won’t help.

Picture 6. False smut obvious on rice panicles.

Picture 6. False smut obvious on rice panicles.

Some bacterial panicle blight has been reported, but only at low levels (Picture 7).

Picture 7. Bacterial panicle blight has been seen in a few fields at low levels.

Picture 7. Bacterial panicle blight has been seen in a few fields at low levels.

 

Enroll fields in the DD50 Program here:       http://DD50.uaex.edu.

Problems or questions:  jhardke@uaex.edu / 501-772-1714.

 

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 jhardke@uaex.edu.

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

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.

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