Arkansas Rice Update 7-14-23

by Jarrod Hardke, Rice Extension Agronomist - July 14, 2023

Arkansas Rice Update 2023-17

July 14, 2023

Jarrod Hardke, Nick Bateman, Ben Thrash, and Camila Nicolli

“I howled at the morning drivin’ rain, but it’s alright now, in fact it’s a gas.”

Good News: Endigo ZCX Approved for Rice Stink Bug Control

Nick Bateman, Ben Thrash, and Glenn Studebaker

Endigo ZCX Section 18 Label and Documentation

Rice stink bug numbers and control with lambda has varied greatly since 2020 depending on where you are in the state. In our assays work with lambda, we have rarely exceeded 65% control with a 1X rate, and no benefit has been observed for going above 1X.

With the limited amount of alternative products available, we applied for a section 18 for Endigo ZCX in April, and finally got the approval today July 14^th. Many folks are already familiar with Endigo ZCX due to the section 18 for Endigo ZC the past two summers. Our experience with this product has been good, and we typically see upwards of 14 days of control. Below are list of highlights around the section 18 and Endigo ZCX. If there are any questions please feel free to reach out and contact us.

Endigo ZCX Highlights:

• Approved from July 14^th through October 15^th

• Rate range is 4.5-6 oz (we prefer 5oz)

• Limited to one application per year

• Maximum of 6.0 fl oz/year

• Pre-Harvest Interval is 21 days

• Area within 100 feet of the edge of the field must be kept free of flowering weeds

Pest Management Time

A surprisingly rainy, muggy, damp week has given mid-July a strange feel.  Given the conditions, sheath blight has really taken off (more on that below).  A good portion of rice in the state is now heading to some degree and that should speed right along over the next two weeks.

We’re expected to heat up this week, and several days of warmer, drier, direct sunlight days should be very good for rice progress.  It will also hopefully slow down some of the disease progress.

The nights are going to get warm during this period, but the expectation is that temps day and night will drop back off some by next weekend.  There are also some reports that we could see some haze from wildfire smoke coming from Canada.  That’s not ideal this time of year, but arguably better than it occurring around joint movement.

There’s plenty in this update on rice stink bug – see the two articles and the podcast links below.

Get out there and scout for stink bugs and sheath blight!

Let us know if we can help.

Fig. 1.  NOAA 7-day precipitation forecast.

New on Arkansas Row Crops Radio this week:

Ento Update 7-14-23:  Endigo ZCX Section 18 Exemption

Entomology Update 7-13-23: Rice Stink Bugs, Plant Bugs, Bollworms

Weeds AR Wild Series, S3 Ep15:  Brake Herbicide Use in Rice

Sheath Blight

Camila Nicolli and Jarrod Hardke

The weather continues to be extremely conducive for sheath blight development and progression.  Continue actively scouting for this disease.  Scout the field in a zigzag pattern, parting the canopy to evaluate a 3-foot section at each stop.

For cultivars rated Susceptible (S) or Very Susceptible (VS) we need to start being concerned when we exceed 33% positive stops.  For cultivars rated Moderately Susceptible (MS) we need to start being concerned when we exceed 50% positive stops.  But just because you reach the positive stops threshold does not mean you need to treat then.

See Fig. 2. for a decision-making checklist for sheath blight.  It includes 1) susceptibility of the cultivar, 2) percent positive stops for sheath blight, 3) health of the upper 3 leaves in canopy, and 4) nitrogen rate and seeding rate used.

Link:  Fungicides and Mix Rates for the Major Rice Diseases

Fig. 2.  Decision-making checklist for fungicide applications to manage sheath blight.

Table 1.  Mode of action group, active ingredient, and disease activity of rice fungicides.

Rice Stink Bug Update

Nick Bateman and Ben Thrash

Phone calls have picked up rapidly over the past 7 days on rice stink bug.  Reports are still varying, with most populations still being somewhat moderate.  With that being said, we have received multiple calls on populations exceeding 70-80 on 10 sweeps.  As more rice heads over the following week these densities should dilute some.

We are still hearing about and getting some questions on adding lambda to a fungicide application.  This is a waste of money (Fig. 3)!  Adding an insecticide, particularly a pyrethroid at this time, is opening the door to make rice stink bug populations higher.  This application will kill beneficials and, if your application timing is correct for smuts, heads should not be out therefore will receive no protection.  The minimal amount of rice stink bugs killed with this application will not offset the potential issues down the road that this can cause.

So, what are our current options for rice stink bug control?  Some folks have been using lambda with mixed but generally ok results in low populations.  Tenchu and Endigo ZCX have been effective on the higher populations that have been observed.  We had/have a limited supply of Tenchu in the state and it is rapidly running out.  As mentioned earlier in the update, Endigo ZCX received a Section 18 for use in rice effective today.  A big thanks to the Arkansas Department of Agriculture and the EPA for working with us on this urgent need.

Fig. 3.  Impact of applying a pyrethroid prior to rice heading on rice stink bug populations.

DD50 Rice Management Program is Live

The DD50 Rice Management Program is live and ready for fields to be enrolled for the 2023 season.  All log-in and producer information has been retained from the 2022 season, so if you used the program last year you can log in just as you did last year.  Log in and enroll fields here:  https://dd50.uada.edu.

Use the Arkansas Rice Advisor Internet App!

The Arkansas Rice Advisor site https://riceadvisor.uada.edu functions like an app on your mobile device.  There you can readily access the DD50 program, rice seeding rate calculator, drill calibration, fertilizer and N rate calculators, publications, and more.

Additional Information

Arkansas Rice Updates are published periodically to provide timely information and recommendations for rice production in Arkansas.  If you would like to be added to this email list, please send your request to rice@uada.edu.

This information will also be posted to the Arkansas Row Crops blog (http://www.arkansas-crops.com/) where additional information from Extension specialists can be found.

More information on rice production, including access to all publications and reports, can be found at http://www.uaex.uada.edu/rice.

Acknowledgements

We sincerely appreciate the support for this publication provided by the rice farmers of Arkansas and administered by the Arkansas Rice Research and Promotion Board.

The authors greatly appreciate the feedback and contributions of all growers, county agents, consultants, and rice industry stakeholders.