Arkansas Rice update 10-7-22

by Jarrod Hardke, Rice Extension Agronomist - October 7, 2022

Arkansas Rice Update 2022-25

October 7, 2022

Jarrod Hardke

“There’s something happening here, but what it is ain’t exactly clear.”

A Quarter and Change

Jarrod Hardke

A quarter or less of the rice crop is left to harvest and a change in the weather is forecast for next week (rain and a temperature drop).  Variability seems to be the best word to describe harvest season this year.  The heat over the course of the summer did its work and depending on planting date and management, yields are bouncing around.  The general trend is a 5% or so reduction in yield, but there are still those on par with last year and some reporting their best yields.  Others have reported major problem fields.

Last year’s yield record of 170 bu/acre wasn’t expected to be challenged, but it’s looking more likely that we’ll fall in the neighborhood of 165 bu/acre for a state average.  The remaining late rice to be harvested will likely tell the story on where we end up, especially with cooler temperatures on the way.

Milling yields have largely held firm with a guesstimate in the 55/70 range (low 50s to upper 50s common).  This is a big improvement over last year that was around a 52/69 with far too much milling in the 40s.  Hopefully this improved milling with lower damaged rice (peck) will help to make up for some of the lower grain yields.

Let us know if we can help.

Fig. 1.  2010-2022 Arkansas rice harvest progress (USDA-NASS).

Preliminary Arkansas Rice Performance Trial Data

Jarrod Hardke

Preliminary results from the Arkansas Rice Performance Trials (ARPT) small-plot testing are now available.  One site remains to be harvested, but planting decisions are already approaching for the 2023 season.  Note this data is subject to change as we finish analyzing data.  Final results will be published around Dec. 1.

A few notes:  all trial locations are managed with a conventional herbicide program to allow for comparison across all technologies; STF site was harvested at very low moisture which may have had a greater impact on early-maturing cultivars; CLA and LAW sites had significant grass pressure resulting in greater plot variability, therefore results from these sites should be evaluated carefully.

2022 Arkansas Rice Performance Trial Preliminary Summary (10-2-22)

Assorted 

Jarrod Hardke

False smut

To paraphrase Ray Wylie Hubbard, “False smut, just sounds nasty, false smut, pretty much is”.

Especially in later rice, the false smut is very noticeable this year.  RT7521FP has resulted in the most calls, mainly because we have a lot of it planted this year and it’s pretty susceptible.  It continues to pop up even in cultivars that we typically don’t see it in much.

Remember that even with a properly timed application of a triazole fungicide (propiconazole [Tilt, Quilt Xcel] or difenconazole [Amistar Top]) you may only see 50% suppression of false smut.  This particular disease is very showy, but even when it appears to be very bad it isn’t usually yield limiting.  It’s often not even impactful on milling, which is very different from kernel smut.

Well, if it’s not yield limiting then why do my lower yielding spots have a lot of false smut?  Typically because there are other underlying issues in those areas.  We generally see that those areas are pretty rank with overall plant health problems due to conditions, management, or both.  In some cases, it’s clearly low potassium (K) and high nitrogen (N) rates.  Plants low in K have a harder time fending off diseases, but even when you have adequate K, if you have too much N the plant is out of balance and you can get results like you are low K.  In hybrid rice, you don’t usually see typical K deficiency symptoms, you just get the problems associated with it.

What about milling?  Surely all those spore balls are hurting milling, right?  Not much.  False smut takes the place of kernels, but even when it looks bad it’s a small percentage of kernels.  Even in high yielding rice fields, 10-20% of kernels are naturally blank.  A healthy plant makes more kernels that it can actually fill – this is normal.  So having a small percentage of kernels lost to false smut doesn’t necessarily impact yield.  As for milling, the spore ball replaces a kernel and is easily broken loose in the harvest process and can easily be sorted out.  This is very different from kernel smut which occurs inside the rice hull and is impossible to easily remove from harvested grain.

False smut starts out with a bright orange color but turns to a very dark green, almost black color, as it matures.  So, you can still end up with a black combine from false smut like you typically see with a kernel smut problem.  Given the dry conditions this fall, the spore balls are drying up and disintegrating which is giving rice a very ugly look.  Once it’s been harvested most of that residue has been blown off of the rice and samples generally look good.

As with any disease, things can change, so if you’re seeing something different please let us know.

Fig. 2.  Mature false smut on rice.

Drain Timing

Draining on time was draining too early in 2022.  Nobody could have predicted that harvest season would remain as hot and dry as it has, but it still caught up with us.  Hence the rule “drain like it’s never going to rain again.”  Some rice began to shut down and cave in or collapse early before grain had dried down.  Adequate water is necessary for a plant to maintain a rigid stalk.  Once it loses enough water (turgor pressure), it will wilt and/or collapse.  This helps to explain some of the untimely lodging/collapse of rice in the absence of any storms. 

Speaking of water, this was a reminder of where we have limited irrigation capacity.  We know there are places we must be more careful with row rice, and maybe even alter our approach to flooded rice.

High Grain Moisture

It’s been hot and it’s been dry, so why won’t this grain moisture drop?  Notice how we don’t have much dew in the morning?  Soil moisture is necessary for heavier dews, and we don’t have much of that these days.  What does dew have to do with grain drying down?  Water is hydrophilic – which is to say that water loves water.  Ever notice that when you drain a rice field, it drains off a lot better when there’s more water in the field?  So, with the grain in the field, the outer portion of the grain is drier and having dew that soaks into the grain will then evaporate off during the heat of the day and “pull” more moisture out of the grain, helping it to mature.  Right now, that isn’t happening.  Think back to when we usually have light showers scattered through harvest, the grain matures faster when we have humidity, and those showers occur.  For now, the drying down process will remain slow for greener rice until something changes.

Fig. 3.  Near mature rice with greener kernels.

Quinclorac is Rough on Reproductive Rice

Over the past few weeks, it has become clear that late applications of Facet (quinclorac) to clean up grass did a number on some rice.  Quinclorac applied to reproductive stage rice can have major impacts on our yield potential.  There are typically no visual symptoms on the plant following the application, but at maturity, heads will be blank (straightheaded) and often there are “twin stems” emerging from upper nodes on the plant attempting to replace the blanked head.

What we’re seeing from these applications are yield losses ranging from 20-100 bu/acre.  Variability in the response involves exact growth stage of the application, rated used, and environmental conditions.  While there may be some differences among cultivars, so far, we’ve seen it in some of everything across varieties and hybrids.

A number of years ago there was a publication documenting this possible yield loss from Mississippi State.  Looking at varieties and hybrids sprayed with a full rate of quinclorac just prior to panicle initiation (PI) up to 14 days after PI, they reported yield losses of 10-20% depending on the year and timing of application.

The take home message is to not apply quinclorac once rice reaches reproductive growth.  It would be even safer to avoid spraying once rice is nearing reproductive growth.

Reference:

Bond, J.A. and T.W. Walker.  2012.  Effect of postflood quinclorac applications on commercial rice cultivars.  Weed Technology 2012 26:183-188.

Fig. 4.  Quinclorac injury to rice causing blank heads and replacement heads.

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.