Arkansas Rice: Improved Weather Hopeful for Grain Fill; Isolated Hail Damage

    Hail damage to heading rice. Photo: University of Arkansas

    Crop Progress

    “Pretty good.  Not bad.  I can’t complain.  But actually, everything is just about the same.”  We’re holding steady as another week goes by and rice rolls along.  Scattered rains over the past 7-10 days have arguably changed the fortunes for many farms.  Irrigation capacity and flood depth maintenance has been an increasing concern and these rains helped with that immensely.

    For those a little less familiar with the impact of a 1-inch rain on a rice/soybean farm: that’s one inch of water added to every rice field, reservoir, and tailwater ditch.  That’s a soybean irrigation you don’t have to make.  And water that runs off is being picked up by reservoirs and tailwater ditches.  It’s a big deal.  And some areas got another rain today.  Winning!

    How many weather sites do you check before you trust what they say?  Right now we aren’t supposed to hit 90 degrees again until Aug. 6.  That’s incredible after the hot run we’ve been on since early May.

    For the majority of rice in the state right now, this fallback to mild daytime highs and overnight lows is almost perfectly timed.  This is pollination and grain fill weather.  So, if we’ve done things right up to this point, we should see the payoff.

    Fig. 1. Cooler weather is just what the doctor ordered.

    Rice Field Day is This Week!  Friday, August 3rd

    The Rice Field Day at the UofA Division of Agriculture Rice Research & Extension Center is this Friday, August 3, 2018 starting at 7:30 a.m.  We hope you’ll join us!  Check out the program details here.

    Date of 50% Heading Slower in Field Compared to DD50 Program

    Heading notes from our planting date trials show that rice plants are not progressing as quickly to 50% heading as the DD50 program suggests.  Comparing DD50 projections to actual in-field measurements, there is a 3-6 day difference.  What this means is, the DD50 program is predicting that 50% heading will be about 3-6 days earlier than it actually is.

    Just another strange part of 2018, as 50% heading predictions are typically very accurate to within two days.  The extreme heat may be partially responsible, but this year’s data will once again be used to make the program increasingly accurate.

    Remember, 50% heading is the time when 50% of panicles have extended above the flag leaf collar.  That’s not much movement.  Typically, our measured date of 50% heading is earlier than when most call a field headed.  It’s a lot easier to call a field headed when you can see panicles far extended, but that’s days after the 50% heading date we use for DD50.

    Just Say No to Revenge Applications

    Barnyardgrass won the battle.  Let it go.  Once rice is heading, there is nothing you can do or spray to bring it under control or prevent it from taking some rice down.  Don’t risk injuring the rest of the crop trying to make yourself feel better.  Too many questions about trying to clean up messes after rice is heading.  Just say no.

    Disease Update


    Reports on leaf blast are calmer this week as the crop is progressing toward heading and grain fill.  Note that if you have detected leaf blast in nearby fields planted with susceptible varieties, it is likely that those neighboring fields may get blast infection.

    Just because you don’t find leaf blast in a field doesn’t mean you can’t get neck or panicle blast.  Check the disease rating of your cultivar and the history of the field to make a decision on whether to spray.

    You may plan a one-time application with the full rate of strobilurin fungicide.  The optimum timing for this application is when most tillers have 30-50% of the head out of the boot (but necks still in the boot).  Late-planted susceptible cultivars are more prone to blast than early-planted rice.  Grain fill can be affected if the flag leaf dries out due to collar blast (Fig. 2).

    Fig. 2. Leaf blast on the lower leaf and collar blast on flag leaf in field with no fungicide.

    Sheath Blight

    Temperatures are lower, but conditions are still warm and humid for sheath blight to creep up the canopy in thick, susceptible rice fields.  Semi-dwarf medium-grains are often more susceptible than taller long-grains.  Fields with excessive N are also prone to sheath blight.

    Continue scouting until 50% heading.  If flag leaves and the two leaves below the flag are not threatened by sheath blight, the crop will likely outrun the disease.

    Sheath blight can weaken the stems of cultivars even late, allowing rice to go down with heavy heads and winds.  Cultivars susceptible to lodging should be the greatest concern.  For later season sheath blight, 8 or 10 oz/acre of Quadris (azoxystrobin) can be used for 14-21 days suppression.

    Remember the pre-harvest interval (PHI) is 28 days.  No fungicides containing propiconazole (Tilt) are recommended for application after heading.

    Kernel smut and false smut

    Warm, humid, and wet weather conditions are favorable for kernel smut.  False smut is more favored by wet and lower temperature than needed by kernel smut.  A field with history, planted with a susceptible cultivar, with thick stands and excessive N fertilizer, are prone to either or both types of smut.  The recommended timing for fungicide protection are between early boot and mid-boot.

    Bacterial panicle blight (BPB)

    As of today (7/27), we have detected BPB in 2 commercial fields, but nothing is overwhelming.  Flowering stages are the most susceptible for BPB infection from neighboring infected plants.  At RREC, panicles with BPB were seen on Jazzman-2, CL272, ARoma17, Titan, and a few other advanced breeding lines.

    At present, nighttime temperatures being down, BPB may not be of concern.  Extended high nighttime temperatures coupled with windy rain enhance BPB development and spread.  Moisture in the form of dew, fog, and mist also encourage BPB disease.  Late-planted rice are often affected more than early planted susceptible rice.

    For help and identification and common questions on BPB go to Questions on BPB.

    Isolated Hail Reports

    Hail damage to rice was reported in Lonoke, Prairie, and White Counties this past week.  Thankfully, most of the damage was confined to small areas.  Fig. 3 and 4 show one of the worst hit areas of a field.  Most plants were broken over and some to the point that panicles were in the floodwater.

    “Luckily” this was only in a paddy or two.  Yield loss probably greater than 50% here while other areas in this and other field about 10-15% yield loss.

    Fig. 3. Hail damage knocking rice panicles over into the water.

    Fig. 4. Hail damage to heading rice.

    Fig. 5. Chemical damage to heading rice, NOT bacterial panicle blight.

    New DD50 Program is Live!

    Check out here for the overhauled DD50 Rice Management Program.  We have tried to make this version extremely user friendly, but in doing so it is a little different than the old version.  If you run into any issue, please call or text me directly at 501-772-1714 or send emails to  It also works great on mobile phones and tablets.

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