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Arkansas Rice Update 4-19-13
Author: Jarrod Hardke, Rice Extension Agronomist

April 19, 2013                               No. 2013-4

Dr. Jarrod Hardke and Dr. Yeshi Wamishe

Planting Forecast

“The rain, boss.  The rain.”  It’s not exactly Fantasy Island these days.  I feel like a broken record, but it’s raining again.  And it’s going to rain again.  We reportedly received one to three inches across eastern Arkansas from yesterday’s rainfall.  Of course there are already rain chances for the middle of next week.  They’ve lowered the chances, but they’re still lurking and they’ve now spread it out over more days.

I said last week that I expected to see a considerable increase in the amount of rice planted, but Monday’s estimate only raised the total amount planted from 4% to 9%.  Not a quantum leap by any stretch.  However, I do think there was a little more planted than that, and hopefully it will be reflected in the next report (or I could be wrong again – it’s happened before).

With all the water I’ve seen everywhere today, I do have concerns about whether a lot of growers will be able to even get back in the field before the next rain event is supposed to occur early next week.  I realize that everyone’s patience is about worn thin and there’s no cure but a crop in the ground.  Just take a moment to remember how big the pain (and cost) is to replant if you force a crop in when you know you shouldn’t.  Some have already resorted to water-seeding this crop, and I have to say that it’s not necessarily a bad idea if you can’t get your field dried out.  Just remember that if all conditions are optimal, we still recommend increasing your seeding rate by 30% for water-seeding.  Also, keep in mind that seed treatments are not labeled for use on water-seeded rice.  It is illegal to water-seed rice that has been treated with an insecticide or gibberellic acid (Release).

Picture 1:  Field near Stuttgart, AR on Wednesday, April 17th.

Finished Rice Field

Picture 2:  Same field on Thursday, April 18th.  The bottom three levees and gates are underwater.

Finished Rice Field - Rain Flooded

Cutoff Dates

There have been a number of calls in the last couple of weeks with people asking when they may need to consider not planting certain cultivars.  With the season getting later and later on us, it’s the right time to start asking those questions.

This is one of the more difficult topics for us to deal with.  While we can certainly provide some guidance based on research and general risk management, we ultimately cannot predict the weather – which will be what directly determines if the advice we give is correct.  There are a few factors for us to consider when deciding what to plant late, primarily related to disease and yield:

Bacterial Panicle Blight – Still Questions

First, there are still plenty of questions surrounding this disease.  We have years when it has been severe and years when it hasn’t.  We don’t have a good handle on how we think it will play out this year either.

Planting date studies have indicated that if you are planting in an area with concerns about bacterial panicle blight, then you should probably think about avoiding susceptible cultivars if you’re planting after the first week of May.  Yes, that basically limits you to hybrids or Jupiter, but you would rather be safe than sorry.  If you want to plant other cultivars, then plant them in areas where you don’t have a major concern about BPB.

Some have pointed fingers at Clearfield pureline cultivars (CL142AR, CL151, etc.) as being worse for this disease than others, but frankly most cultivars are susceptible (S) or very susceptible (VS) and there is not enough information to split that fine of a hair yet.

Blast – Not Gone, Not Forgotten

We haven’t had as many issues with rice blast in recent years, but that doesn’t mean it has gone away.  In late-planted, blast-susceptible varieties, a 4+ inch flood depth is needed across the field with adequate nitrogen and a timely fungicide application (if needed).  As we move to later planting, it’s possible that a normal August/September could put more strain on your water availability and your ability to maintain a deep flood for blast prevention.  But when’s the last time you saw a “normal” August/September?

If you have concerns about managing your water on a field to help prevent blast in a susceptible variety, then it would be best to plant a less susceptible variety (i.e. Taggart, Mermentau) or hybrid rice for that field.  Quite honestly, if you have concerns about managing your flood for rice production – stop and ask yourself if planting rice on that field is truly in your best interest.

What Do the Planting Date Studies Say?

I’ve put together a figure and a table that I hope will show you what you need to know.  Both of these were made using data from our DD50 planting date studies from 2006-2012.

Figure 1 shows the overall picture of yield decline as we plant later in the year.  That’s averaged across all cultivars we’ve looked at in these studies over the years mentioned.

Fig. 1 DD50 Planting Date Studies - Grain Yield Summary 2006-2012

Table 1 shows selected cultivars from those same studies.  The table lists cultivar, planting date by month, number of years the cultivar has been evaluated at that planting date, yield in bushels per acre, and percent of maximum yield (March yield considered maximum).

Table 1.  Effect of Planting Date on Yield

CultivarPlanting DateYearsYield (bu/A)% of Max Yield
RT CLXL729March4236.4100%
RT CLXL729April4228.897%
RT CLXL729May4193.282%
RT CLXL729June4159.868%
RT CLXL745March4205.9100%
RT CLXL745April4198.196%
RT CLXL745May3174.985%
RT CLXL745June4135.166%
RT XL723March3237.4100%
RT XL723April3227.696%
RT XL723May3204.886%
RT XL723June3147.862%


The first thing that probably catches your attention is that yields are highest in March – regardless of what you plant.  Francis was the only exception, but we only have limited observations.  Speaking of limited observations, you’ll notice there are a few places where the trend is bucked – but also note that happens when we have very few data points.  Some might call it an anomaly.

The next thing that caught my attention was that for the most part, expected yield appears to decline at a surprisingly even rate across all cultivars.

The final thing I would like to point out from this table is that the hybrids seem to maintain more of their yield potential into the April planting dates.  That tells me that if I’m planting a combination of both varieties and hybrids, then I’m putting my varieties in the ground first to maximize their yield potential.  An added delay in planting won’t hurt me as bad with the hybrids.

Planting that way may run the risk of putting your later maturing rice ready to harvest at the same time as your early maturing rice, but times are about to start getting desperate.

Fig. 2 Effect of Planting Date on Yield - DD50 Planting Date Studies 2006-2012

Figure 2 helps to show that there are a million ways to present any set of data.  It also shows that you can make a figure difficult to read by trying to put too much data together, but in this case separate figures wouldn’t illustrate the point.

This figure was generated using the same data used to create Table 1.  The reason for showing this figure is that I believe it shows the declining yield trends are fairly equal between conventional varieties, Clearfield varieties, and hybrids.

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

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


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

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

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