Arkansas Rice: Drain Timing; 1st Fields Nearing Harvest

    ©Debra L Ferguson

    Crop Progress

    “It’s not so much the heat, it’s the humidity.”  But seriously, that describes current conditions.  Temperatures are pretty nice, but the humidity is keeping it a little miserable during the warmer part of the day.

    We’re on deck for the first field in the state to be cut anytime now.  The relative cool down and cloudy, rainy weather over the last 10 days have slowed things enough that nothing was ready to come out this week.  Next week, weather permitting, the first fields will be harvested.  We’re currently forecast to have rain chances with highs in the mid-80s.  Only time will tell.

    Table 1 shows the projected week of 20% grain moisture as things currently stand.  However, as noted last week, actual crop progress is running a few days behind expectations from the DD50 program so expected 20% should be pushed back a few days.  Even taking that into account, we’re still ready for rice harvest and the fields drained for a week or more agree with that.  Draining will really start picking up speed through next week.

    Harvest reports out of the Gulf region sound like they’ve improved from good to good-excellent, but it’s still early.  That can mean good things for the Mid-South.  The crop is shaping up well, but may stop short of a bin buster with the heat and grass issues.  Will an increase in planting of new cultivars this year bridge some of that gap?  Only the Shadow knows.

    Table 1. Projected date of 20% grain moisture based on DD50 enrollment.

    Thanks to all attendees and sponsors of the 2018 Rice Field Day

    The Rice Field Day today was a huge success!  ~400 in attendance with over 250 on field tours.  Thanks for letting us show off what we do to help rice growers in Arkansas.  The work on display today wouldn’t be possible without the rice checkoff support administered by the Rice Research & Promotion Board.

    Fig. 1. Attendees at the breeding stop at the 2018 Rice Field Day.

    Drain Timing

    Speaking of the DD50 program, with many fields nearing drain time, let’s review the preferred rice condition at draining.  The DD50 program gives an approximate drain date of 25 days after 50% heading for long grains and 30 days after 50% heading for medium grains.  Depending on the season, the preferred time can vary depending on temperature, rainfall, and humidity.  So, Fig. 2 provides a general guideline for draining depending on your soil type.

    For loamy soils, it’s typically safe to drain when 2/3 (67%) of panicles are straw colored.  For clay soils, it’s typically safe to drain when 1/3 (33%) to 1/2 of panicles are straw colored.  With field variability there’s no perfect answer, so lean on the safe side.

    Fig. 2. Rice panicles at different maturity levels described by kernel percent straw color: (L) 100%, (C) 67%, and (R) 33%.

    Insect Update

    Rice stink bug pressure has been light until this week.  Some fields are seeing re-infestation, but still at low-moderate levels, just enough to warrant treatment.  We may not get by as easily as we hoped, but most of the crop seems to be outrunning the potential for large infestation events.  Remember that once fields have over 60% hard dough (straw colored kernels), insecticide applications can be terminated.  However, use caution in fields with uneven maturity.

    Row rice fields are known to have a tendency to see damage from billbug (Fig. 3).  With the rapid increase in row rice acres this year, that’s coming as a surprise to many.  It’s showing up now because they seem to move into fields sometime after midseason and burrow into the base of stems near the soil line.  This is why they’re typically only a problem on levees, but in the unflooded portions of row rice fields they have more area to infest.

    Once they feed into the base of the stem, you don’t know they’re in there until a white (blank) panicle emerges (Fig. 4).  There is no recommended treatment once you find them.  The damage is done.  We’re working on finding seed treatment and/or insecticide options to manage this pest – trials were planted this spring and are being evaluated now.

    Fig. 3. Billbug larva in the base of a rice stem in a row rice field.

    Fig. 4. Blank panicle due to billbug damage.

    Disease Update

    As early-planted rice goes through maturity some instances of panicle blanking may be of concern.  Panicle blanking refers to no seeds in panicle florets.  Although a certain percentage of blanking may often occur across a panicle, there are several biotic and abiotic factors that are responsible to fully or partially leave florets without seeds.  As a results, some panicles with no seeds in them remain upright as others tip (turn down) as grain fill progresses.

    Common Biotic Factors Responsible for Panicle Blanking:

    • Neck blast (Fig. 5)
    • Panicle blast (Fig. 6)
    • Bacterial panicle blight (Fig. 7)
    • Insects such as stem borer (Fig. 8)
    • Bird depredation (Fig. 9)

    Common Abiotic Factors Responsible for Panicle Blanking

    • Drought (Fig. 10)
    • High nighttime temps, rain or cold temps during pollination (Fig. 11)
    • High wind speed (Fig. 12)

    Fig. 5. Fully or partially blanked panicles due to neck blast.

    Fig. 6. Partially blanked panicles due to panicle blast.

    Fig. 7. Fully or partially blanked panicles due to bacterial panicle blight.

    Fig. 8. Panicle blanking can be caused when nutrient flow is interrupted from roots by stem borer or bill bug damage.

    Fig. 9. Partially blanked panicles due to bird damage.

    Fig. 10. Panicle blanking in drought stressed row rice.

    Fig. 11. Blanked panicles caused by pollination failure due to environmental conditions, discolored by saprophytic growth.

    Fig. 12. Panicle blanking due to high wind speed, often seen on field edges and levees.

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