Arkansas Rice: Cooler Conditions Expected, Lots of Pests to Worry About

Rice Stink Bug

If you’ve been in the field this week then you’ve been cooking.  More conversations have turned to debating whether it’s better to be out in the morning in the higher humidity and heavy dew or later afternoon when it’s drier but hotter.  Opinions vary, but either way it’s hot.

It does appear that relief is on the way this weekend.  Temperatures are expected to drop below normal beginning Sunday and stay somewhat mild through the week.  As we struggle to stay caught up on irrigation efforts, this will be a welcome relief.  Some rainfall is expected on Sunday but amounts and locations still look up in the air.  May everyone get just what they need!

Difficulty keeping fields flooded and early season weather making herbicide applications difficult are finally showing through in the form of weed escapes.  Grass is beginning to make it out of the canopy in areas that seemed pretty clean throughout much of the year so far.

Often the pressure looks worse than it really is at this point as large tillering grass makes populations looker thicker.  Certainly, there will be lodging concerns in those areas of the field come harvest time.

A major note for this week is that, due to rising numbers of COVID cases, the decision has been made to CANCEL the Rice Field Day at Stuttgart on Aug. 6 and the Rice College at Pine Tree on Aug. 12.  If you paid a registration fee for Rice College, it will be refunded.

We’re disappointed not to have these events, but the safety of attendees comes first.  In their place, we plan to video the content from these events and make them available online at a later date.  It’s not a perfect substitute for in-person, in-the-field events, but we’ll try to make them as close as we can.

Insects:  Good News and Bad News

The good news is we were successful in getting a crisis exemption for the Intrepid 2F for use in rice to control armyworms.  The specific exemption is still under review at EPA and it may be another month before they make a final decision, but as of July 28 we are legal to spray in Arkansas.

If something changes, we will let everyone know immediately.  We have observed great efficacy with 4 oz.  Some highlights for the exemption are listed below.

Intrepid 2F Crisis Exemption Highlights:

  • Rate range is 4-8 oz.
  • A maximum of 2 applications per year.
  • 14 day preharvest.
  • 10 day retreat interval.
  • A copy of the label must be in possession at the time of application.
    • Copy of label can be obtained here.
  • All applications must be reported to the Arkansas Department of Agriculture within 10 days of application.

Some of the calls we are getting on armyworms currently are for headed rice.  Once rice is headed we are still concerned about defoliation, especially if it exceeds 20%.  This isn’t common to see in headed rice, however it can happen.

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One thing to keep an eye out for is if armyworms are moving on to the panicle.  We have documented them feeding on blooms and in some cases seed, which can lead to a reduction in yield.  If this is observed, treatment may be warranted.

Keep in mind that armyworms on panicles are very exposed, and we would expect to do a better job with lambda-cyhalothrin (Warrior II, Lambda-Cy, etc.) than when armyworms are down in the canopy.

Rice Stink Bugs

With all of the armyworm issues going on in rice, we haven’t talked much about rice stink bugs.  In some places in the state, folks are on their second and third applications.  Most of these situations are because they are the only headed rice around and keep getting reinfested.

We are getting questions in a lot of these cases on whether or not we should swap to Tenchu and stop spraying lambda.  We have made several collections from these locations over the past week and are not seeing issues with lambda yet.

A sign of control failure is having nymphs following an application, if it is just adults, then it is most likely a reinfestation.  Please contact us if you feel you are not getting adequate control with lambda so we can conduct some bioassays.

Acephate Use in Rice – The Bad News

The last thing we want to cover is the use of acephate in rice.  This is an illegal application and runs the risk of jeopardizing the rice industry as a whole.  We have gotten a few questions about using acephate for both fall armyworm and rice stink bug control.  Once again, this is highly off label.

Acephate is easily detected in grain even at drift rates.  Our work has shown that a direct application or drift rates lead to levels that are high enough to be rejected at foreign ports.  Please do not use acephate in rice.




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