Arkansas Rice: Harvest Picks Up, Yields Not So Much

    Crop Overview

    Harvest continues to pick up speed in the southern half of the state.  Unfortunately yield reports have yet to pick up along with it.  The general consensus seems to be that yield numbers are running in the neighborhood of 10% off from previous years.  Occasional exceptional fields are out there, but they’re by far the exception, not the rule.

    The other potential downside that remains to be seen is chalk – caused that period of high nighttime temperatures mostly experienced in the southern half of the state.  North of I-40 only a few fields have been cut and those numbers sounded much closer to performance from recent years and may have fewer quality issues due to missing out on some of the high temps.

    Rain chances this weekend give way to mild temps next week.  This will likely slow crop maturity and grain drying in the field depending on humidity.  Conditions favorable for disease.

    The initial August FSA acreage report was released this week (Table 1).  So far it shows that almost 1.29 million acres are enrolled (the number will likely increase each month until the numbers are finalized in January).  So we could still get close to the 1.39 million acre prediction from July.  The most notable takeaway was 267,000 acres listed as prevented planting.

    According to DD50 enrollment, 36% of fields have reached harvest moisture (20%) (Table 2).  Rainfall this past week likely returned some moisture to fields drying down rapidly, but the dry air that moved in behind it may reverse that quickly.

    2015-25 Table 1 FSA Crop Acreage

    2015-25 Table 2 Harvest

    Harvest Aids

    With a lot of green foliage remaining in fields, a number of growers have already used harvest aids to improve desiccation and make harvest easier.  Sodium chlorate is a useful tool – used correctly it’s very beneficial, used incorrectly and it causes more problems than it solves.

    Sodium chlorate should only be applied once grain moisture is below 25% and do not apply if grain moisture is below 18%.  After application the foliage begins to dry down and so do the grains.  In just a few days you can lose up to 5% grain moisture – so plan to harvest no later than 4-7 days after application.  DO NOT apply prior to rainy periods when immediate harvest is not possible.

    2015-25 RSB in late rice

    Rice stink bugs showing up in high numbers in late heading fields – SCOUT!

    2015-25 Glyphosate drift

    Glyphosate drift to reproductive stage rice can leave you with parrot-beaked kernels and blank heads. Note the shortened, twisted flag leaves to differentiate from straighthead.

    Disease Update

    Sheath Blight:  Keep scouting in late-planted rice.  Although the temperatures appear to cool down, with the current wet conditions the disease can still progress slowly in fields planted with susceptible cultivars – especially with high N rates and thick stands.  In some instances, sheath blight (Fig. 1) can be confused with sheath spot diseases of rice (Fig. 2).  Fungicides are not recommended for either aggregate or bordered sheath spot diseases of rice.

    2015-25 Fig 1 Sheath blight

    Fig. 1. Sheath blight in rice requires fungicide application at the recommended threshold level.

    2015-25 Fig 2 Sheath spot

    Fig. 2. Sheath spot disease so far is considered a disease of low economic importance.

    Blast:  Serious concern in late-planted rice.  Frequent rain, overcast, slow wind, and lower temperatures than required by sheath blight encourage blast disease development in prone fields planted late with susceptible cultivars.  Leaf blast is mostly managed with flood depth of at least 4 inches.

    However, blast-prone fields with history, planted with susceptible cultivars and excessive N rates require preventative fungicide treatments for neck blast.  Fields with heavy tree lines, difficult to water, get foggy from nearby waterways or low-lying areas are all “blast-prone fields.”

    While planning preventative fungicides for neck blast, “timing in relation to the crop stage” is crucial.  Fungicides applied after the head is completely out of the boot will not be beneficial to control neck blast of rice.  The first application needs to be made from late boot to 10% head out in the main tillers and the second from 50-75% head out.

    “Head out” refers to the percent length of the panicle that is out of the boot.  It is important that the necks are still in the boots to benefit from a fungicide application.  Once the necks are completely out of the boots, fungicides do not prevent neck rot from blast.

    Bacterial Panicle Blight:  All suspicious samples received so far from commercial fields tested negative.  Example of suspicious sample for BPB shown in Fig. 3.

    2015-25 Fig 3 Negative for BPB

    Fig. 3. An example of a sample obtained from commercial fields that tested negative for bacterial panicle blight.

    Kernel smut:  can be easily detected and identified usually in the morning when seeds get swollen with moisture.  Some dark kernels with sooty molds (Fig. 4) at crop maturity may be confused with kernel smut (Fig. 5).  If seeds have kernel smut, black spores fill the kernel and the spores ooze out when seeds are opened (Fig. 5).

    2015-25 Fig 4 Sooty mold

    Fig. 4. Sooty mold can be confused with kernel smut.

    2015-25 Fig 5 Kernel smut

    Fig. 5. Black spores ooze from kernels infected with kernel smut.

    False smut:  The lower temperatures with frequent rains encourage false smut development.  Therefore, it is a disease of concern in late-planted rice.  Rice seeds harvested with false smut galls or kernel smut spores are not acceptable to parboil (Fig. 6).

    2015-25 Fig 6 False smut

    Fig. 6. False smut spores in harvested grain.

    Protective fungicides for kernel smut and false smut:  Fungicide rate, timing, and coverage are important to suppress both kernel and false smut.  The fungicide recommended rate is a minimum of 6 fl oz/acre of Tilt (propiconazole) or Tilt equivalent.  The correct timing is between early boot and mid boot.  Fungicides applied prior to early boot or past late boot are not beneficial.

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