Arkansas Rice: Too Much Heat, Too Little Water – Disease Questions

    Rice on the verge of heading. Photo: University of Arkansas

    Crop Progress

    “Hey hey, my my, rock n’ roll will never die.”  It’s Friday the 13th and there’s bad news to report – go figure.  Mainly we’re talking about heat and water.  Too much heat and too little water, that is.

    We’re in the middle of a window of high nighttime temperatures that really need to give.  Rice flowering during this period could see reduced pollination – possibly leading to yield loss if it continues.  The forecast is for that to begin to break up the middle of the coming week and overnight lows fall into the lower 70s.  We really need this to happen.  Short period of high nighttime temps can be managed by the rice plant.  Extended periods of more than 4-5 consecutive nights are the real danger point during heading.

    Even if temperatures fall a little, the water situation is getting real.  It could be argued that soybeans and corn will take it harder because there is little water for them to be taken away from rice.  However, there is an increasing concern that surface water supplies, critical sources for many growers, will not last the next 30 days they are needed to finish out this rice crop.

    At Stuttgart, since a 1.6 inch rainfall event on April 23, the area has received a total of 1.91 inches of rain spread over 11 rainfall events.  So next to nothing.  The largest event was 0.4 inches.  Over that 82 day period, 50 days have had temps of 90 or greater.  Tough irrigation demands by any standard.

    The rice crop still looks good.  I still have pretty high expectations for how we’ll turn out.  But we have to have the water to get us there.  If we run out of water before grain fill is complete, a lack of soil moisture can hurt yields.  Cross fingers and toes that we get some rain, or at a minimum some temperature relief, to get acres to the finish line.

    Fig. 1. Rice on the verge of heading.

    Leaf Blast Update

    Between June 6 and July 12, rice leaf blat has been reported from 15 counties – Arkansas, Clark, Clay, Greene, Lawrence, Logan, Lonoke, Monroe, Poinsett, Pulaski, Randolph, St. Francis, White, Woodruff, and Yell on Titan, Jupiter, Diamond, CL153, Roy J, PVL01, and CL151.  Reportedly blast appeared in these counties in blast prone fields or field spots favorable for blast disease development.  To suppress leaf blast from burning down the leaves, water depth needs to be raised to at least 4 inch depth.

    Common Questions on Management of Sheath Blight

    1. I see active sheath blight at green ring. The variety is semi-dwarf and I do not want to take risk.  Could I tank mix the strobilurin fungicide with a grass herbicide?

    You should check the new labels for restrictions before you tank mix.

    2. Some spots in my field have thicker canopy than others. I see sheath blight moving actively in the thicker spots.  Should I spray for sheath blight?

    In such a field it may be difficult to know the threshold level.  Therefore, it is a judgment call.  See if those areas are not the bottom of the field.  Often field bottoms can have more sheath blight.

    3, If sheath blight appears at green ring, moving fast and reached threshold level, how many times do I need to spray for sheath blight in a season to minimize yield damage and maximize profit?

    You have to make your 1st application anyway since the fungus is moving fast and is at threshold level. However, you need to consider different factors to make the 2nd application decision. The susceptibility and height of the cultivar, the Preflood nitrogen rate, the seeding rate, and the rate and kind of fungicide you applied the first time.

    Highest rate of azoxystrobin (Quadris) fungicide would protect up to 4 weeks. As long as the upper two or three leaves are healthy at around 50% heading the impact on yield may not be that big and the crop may benefit little from 2nd application. In Arkansas a one-time application is recommended. Fields benefit from fungicides if well managed.

    4. If I plan for just one-time application for sheath blight control on a susceptible cultivar, what is the optimum developmental stage I should spray the fungicide?

    Panicle differentiation to mid-boot.  This can be synchronized with protection fungicides for the smuts.  In such cases, combination fungicides having triazoles with rates of at least 6 oz/acre Tilt equivalent are preferred.

    5. Is sheath blight on hybrid rice XP753 need fungicide treatment? The blight is just above the water line but it looks to be in more than 50% of stops.

    Remember, as long as the upper two or three leaves are not affected at around 50% heading, fungicides are not recommended.  Scout the progress of the disease relative to the plant height to make your judgement to apply or not to apply.  Weather factors are important to consider in your decision.  Sheath blight can advance fast under warm and humid conditions in a crop with a thick canopy.

    6. I have lots of water and the flood is now about 6 inches deep. The field is planted to hybrid.  Is there any risk for rice disease in this situation?

    The sheath blight disease usually starts at the water line.  If infection occurs, the disease may start from high in the plant height and reach the upper leaves in a short time.  Since this field has low to no risk for blast, lowering or turning off the pump would be helpful.

    Fig. 2. Sheath blight development.

    Rice Field Day Scheduled for Friday, August 3

    The Rice Field Day at the UofA Division of Agriculture Rice Research & Extension Center is scheduled for Friday, August 3, 2018.  Full details can be found here.

    Insect Update

    Rice stink bugs (RSB) are in early rice at 5-10 per 10 sweeps. Some fields are still below treatment level. Remember to scout in the early morning and late evening when RSB are up in the canopy and in the field.

    These are also the best times to spray when RSB reaches treatment threshold. So far there haven’t been reports of big numbers in fields. Treat for 5 RSB per 10 sweeps the first two weeks of heading; treat for 10 RSB per 10 sweeps the second two weeks of heading.

    Also, do not mix in an insecticide with your fungicide application prior to heading. There may be a few stink bugs scattered in the field on escaped grasses, but the levels are usually very low. Do not treat until you reach threshold after 75% of the field is heading.

    Fig. 3. Rice stink bug on heading grass on field edge.

    Rice PLC Update

    In the July WASDE report USDA projected the 2017 producer price for long-grain would be $11.70 per cwt or $5.265/bu.  A projected PLC Payment Rate can be estimated by subtracting $5.265/bu from the PLC Reference Price of $6.30/bu.  The result is a projected PLC Payment Rate of $1.035 per bushel (not accounting for sequestration).

    For the previous three crop years ARC and PLC payment rates have been reduced by 6.8 percent.  Applying that same percentage reduction, the net 2017 PLC payment would be 96 cents per bushel.  The final 2017 marketing year prices and PLC payment rates for rice are expected to be announced in October 2018.

    2017 Projected PLC Payment Rates, Rice. (July 2018). Click Image to Enlarge

    Projected 2017 PLC payment rates are updated monthly on the USDA Farm Service Agencies’ ARC/PLC website at this link: ARC/PLC Program Data.

    Look under the heading “Program Year 2017 Data” for “Projected 2017 PLC Payment Rates”.

    The 2017 producer price for southern medium grain is projected to be $12 per cwt or $5.40 /bu, which equates to a PLC payment of roughly 90 cents per bushel.  As a reminder, PLC payments are made on 85% of base acres and 90% of historical average yields.

    Market Comments

    Since trading to a low point of $10.24 in June, the September contract has posted higher weekly settlements for the three previous weeks. Trading ran into resistance just above $12.10 earlier this week.

    The July WASDE was anticipated to be bearish as it included increases in long grain acreage from the June NASS Acreage report.  This in turn increased expected 2018 production by 6.3 million cwt.

    Some of the added production was offset by a 3 million cwt increase in domestic use. There were no changes to exports. Ending Stocks for the 2018/19 marketing year are now projected at 29.4 million cwt, up 2.3 from last month and 9 million above the expected 2017/18 ending stocks.

    The mid-point of the USDA’s price range for the 2018 crop is currently $11.20/cwt or $5.04 per bushel.

    Use the price charts for the September contract as a guide for placing hedges. The price band from $12.10 to $12.30 has been an area of overhead price resistance this year. The market is retesting the lower end of that price band this week. The next USDA Crop Production and WASDE report will be released on August 10, 2018.

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