Arkansas Rice: Crops Are Heading – Will Temps Cause Flowering Stress?

    Crop Progress

    “Listen, do you smell something?”  That would be the start of heading in Arkansas rice.  The first fields are just starting to pop heads this week 50% heading beginning on fields this weekend.

    What we really need is to shave a few degrees off our temperatures.  As we enter the heading stage of the crop, it’s important that we have cool enough overnight temperatures to avoid temperature stress at flowering.  Right now we’re toeing the line of the magical 75 degree mark for overnight lows.  If we climb up above that we could be in trouble.  If we stay right at or below it we may be fine.

    Despite the fact that this crop was planted later than the previous two years, our overall progress is much further ahead thanks to May and June temperatures.  What that means is heading earlier in the summer with longer days and more sunlight.  This is generally a good thing for yield potential.

    The downside for yield potential has been getting floods established to incorporate nitrogen timely and keeping early-season weeds under control.  Without some rain coming into play, irrigation may become an issue and some crops will have to do with less.  So, the yield outlook is a mixed bag as it’s difficult to determine which factor will win out.

    The first fields are currently forecast to reach harvest moisture the first week of August.  So, we’ll know pretty early what the yield trend will look like.  Harvest efficiency will be key as much of this crop will come off all at one time.  So there are still plenty of hurdles between now and a crop in the truck.

    Crop Acreage Report

    The USDA-NASS acreage report was released today (6/29).  For Arkansas, planted acres are listed at 1,391,000 with 1,210,000 long-grain and 180,000 medium-grain.  From that, expected harvested acres are 1,376,000 total with 1,200,000 long-grain and 175,000 medium-grain.  Table 1 shows forecasted harvested acreage for all states.

    My personal expectation was for 1.4 million total acres planted with at least 220,000 acres of medium-grain (if not higher).  I expect this to still be the case and be resolved in the harvest numbers this fall.

    Table 1. Forecast 2018 rice harvested acreage. Click Image to Enlarge

    Glufosinate is NOT Labeled for In-Crop Use in Rice

    A labeling error was discovered this week in regard to some generic glufosinate formulations.  The labeling wrongly gives the idea that glufosinate can be sprayed over the top of rice – IT CAN’T!  You will injure and/or kill rice with an application of glufosinate.  This concludes your public service announcement.

    Rice Disease Update

    Leaf blast:  Between June 6 and June 28, rice leaf blast has been reported from 7 counties – Lonoke, Randolph, Poinsett, Pulaski, Lawrence, Greene, Woodruff, and Monroe on Titan, Jupiter, Diamond, CL151, and Roy J.  Reportedly blast appeared in these counties in blast-prone fields or field spots favorable for blast disease development.

    Typically rice blast shows diamond-shaped lesions often with ashy center (Fig. 1).  However, lesions can vary at earlier stages (Fig. 2).  To suppress leaf blast from burning down the leaves, water depth needs to be raised to at least 4 inch depth.

    Fig. 1. Typically rice blast shows diamond-shaped lesions often with ashy center.

    Fig. 2. Various sporulation levels of blast lesions in rice

    Sheath Blight:  As Arkansas rice is moving to reproductive stages, diseases are also progressing.  Reports have started coming in this week on sheath blight (Fig. 3) in susceptible rice.  Sheath blight often starts a few weeks after permanent flood established and may progress vertically on plants and horizontally to neighboring rice plants.  Automatic application of fungicides is highly discouraged.  Please read Arkansas-reproductive-scouting.

    Fig. 3. Sheath blight on a very susceptible cultivar at around early boot development stage

    Kernel and false smut:  The probability of having severe smut is higher in rice fields with a history of smut and use of excessive nitrogen rates.  There is no scouting threshold for smuts; therefore, they are suppressed by triazole fungicides applied at the correct timing and rate.  For more information see a common mistake-waiting too long.

    Rice Field Day Scheduled for Friday, August 3rd

    The Rice Field Day at the UofA Division of Agriculture Rice Research & Extension Center is scheduled for Friday, August 3, 2018.  More details will follow.

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