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21
Jun
2013
Arkansas rice update – June 21, 2013
Author: Jarrod Hardke, Rice Extension Agronomist

June 21, 2013                             No. 2013-13

Dr. Jarrod Hardke, Dr. Gus Lorenz, Dr. Bob Scott, and Dr. Yeshi Wamishe

Crop Progress

We’re moving on up.  The rice is looking better and better from top to bottom in the state.  Warm temperatures and high humidity have most of the crop really moving in the right direction.  Some growers were unfortunate enough to catch another heavy rainfall earlier in the week that will set them back once again, but most avoided anything and have continued to make great progress.

The forecast for the next ten days looks great for crop progress as well.  Temperatures will remain in the low to mid-90s with only slight chances of rainfall.  A little shower here and there to help maintain flood levels in the heat won’t be the worst thing.  However, if the trend of this year continues, those who don’t need rain will get it, and those who need it won’t get it.

We’re continuing to see some herbicide issues as has become routine.  Some combination of drift, increased sensitivity to normal herbicide sprays, and carryover from last year’s soybeans seem to be the most common cases.

Picture 1.  Keeping it clean.OLYMPUS DIGITAL CAMERA

Tables 1 – 3 provide some perspective on crop progress and will be updated during the season.  Constantly changing weather will certainly shift them around – hopefully in our favor.

Table 1.  Percent of rice acres to reach ½” IE during listed weeks of 2013 according to current DD50 enrollment.

½” IE Date

Percent

June   15-21

22%

June   22-28

36%

June   29 – July 5

24%

July   6-12

12%

July   13-19

4%

July   20-26

1%

Table 2.  Percent of rice acres to reach 50% heading during listed weeks of 2013 according to current DD50 enrollment.

50% Heading Date

Percent

July   5-11

2%

July   12-18

31%

July   19-25

32%

July 26 – Aug 1

21%

Aug   2-8

10%

Aug   9-15

3%

Aug   16-22

1%

Table 3.  Percent of rice acres to reach harvest timing during listed weeks of 2013 according to current DD50 enrollment.

Harvest Date

Percent

Aug   10-16

1%

Aug   17-23

24%

Aug   24-30

27%

Aug   31 – Sept 6

28%

Sept   7-13

13%

Sept   14-20

4%

Sept   21-27

2%

Rice Water Weevil Alert

Rice water weevil (RWW) adults are beginning to show up in flooded rice fields across the state.  If you have fields that did not receive an insecticide seed treatment – scout closely for feeding scars and presence of adults.

Timing is extremely critical when attempting to control RWW with foliar insecticide sprays.  Sprays need to be made 5-7 days postflood.  Products labeled for control of RWW adults include pyrethroids (Karate Z, Mustang Max, and Declare) and a neonicotinoid (Belay).  Always read and follow label directions.

As Rice Advances, Watch Out for Diseases

As the temperatures get better, most of the flooded rice fields in Arkansas appear to be growing nicely and tillering well.  Likewise, disease pathogens also start growing nicely and take this opportunity to reproduce to their best potential under warmer temperatures and dense canopies.  Before too long, some diseases may start to show up.

In the second week of May, there were reports of leaf blast on CL151 in some areas in Louisiana and the wet conditions also have allowed sheath blight to start developing (Groth, Rice Newsletter No. 12).  As a result, fungicide applications have started in south Louisiana in some earlier fields on a limited basis.  In order to make timely decisions for management of sheath blight with fungicides, frequent scouting is needed to effectively monitor disease progress.  Read more at: http://www.arkansas-crops.com/2013/06/10/scout-for-sheath-blight-disease-of-rice-from-green-ring-until-pre-heading/.

Blast spores could be carried by wind from a distance if they are not already in Arkansas.  However, so far there is not any report of blast in Arkansas.  The pathogen being seed- and air-borne, blast can affect plants early in plant growth.  Frequent scouting is also needed for rice blast in order to stay ahead of the disease.  If leaf blast is apparent or suspected, you need to pump the water depth up to 4 inches or more.  The deep flood needs to be held until it is time to drain the field.  This will minimize the risk of neck blast.  You need to be prepared to spray an approved fungicide before heads emerge – with some situations requiring multiple applications.  Make the first application at late boot to boot-split and the second when heads are about 2/3 out on the main tillers.  Be sure the panicle bases on the main tillers are still in the boot during the second application.  When relying on a single application, timing is critical.  Be sure at least 1/3 of the panicles are still in the boot.  The fungicides will not be as effective once the heads are fully out of the boot, so do not wait too late to apply the fungicide.  Read more at: http://www.arkansas-crops.com/2013/05/16/diseases-may-be-a-concern-in-late-planted-rice/

also at http://www.arkansas-crops.com/2013/02/27/rice-blast-overwintered-in-louisiana-review-of-management-options-for-arkansas/.

Akiochi, also called hydrogen sulfide toxicity, needs to be closely watched, particularly in fields with a history of this phenomenon.  The cause of the condition is not fully understood.  The major culprit is the formation of hydrogen sulfide in some soil types.  Research has indicated hydrogen sulfide, even in low concentrations, can be toxic to roots and will affect the plant’s ability to take up nutrients from the soil.  Cold water and iron from wells were also thought to aggravate the situation.  Although the disease appeared worse near the wells, it was also severe in spots far from wells.

Last week (6/12), a Japanese soil scientist, Lance Schmidt, and Dr. Wamishe visited a verification field of Roy J in White County, AR.  The water from the well had the look and smell of iron (Picture 2) and the rice stand closer to the well looked thinner than the rice further away from the well (Picture 3).  The floodwater had many air bubbles on the surface both near the well and in the rice field, which is thought to be an indicator of Akiochi (Pictures 2 & 3).  We pulled out some seedlings and looked at the roots – most root systems were normal in appearance but one seedling did have roots that were beginning to blacken.  The current conclusion is that it is too early to see significant root blackening since the field has only been flooded for two weeks.  We will continue to watch this field.  Read more on Akiochi at: http://www.arkansas-crops.com/2013/05/23/weather-and-akiochi-disease-of-rice-is-there-a-link/.

Picture 2.  Suspicious water source for hydrogen sulfide toxicity phenomenon.2013-13 Picture 2

Picture 3.  Thin rice stand near the water well with tremendous air bubbles.2013-13 Picture 3

Need Help with DD50 Enrollment?  Call or E-mail Me or Your Local County Extension Agent

If you prefer to enter them yourself, please visit http://dd50.uaex.edu/dd50Logon.asp.

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 jhardke@uaex.edu.

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

Acknowledgements

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

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


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