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27
Jun
2014
Arkansas Rice Update 6-27-14
Author: Jarrod Hardke, Rice Extension Agronomist

June 27, 2014                             No. 2014-16

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

Crop Progress

The rice crop has been on the move this week.  Some rice in the state has begun to head, but most is right at midseason now with fertilizer applications going out.

Disease and insects have been on the move and are the big stories of the week.  Fall armyworms have moved into the southern and central portions of the state and will likely continue to migrate north.  The first confirmed reports of leaf blast, sheath blight, and autumn decline have also come in this week.

While drift complaints have tapered off in the last week, please continue to avoid situations that have a strong chance of drift onto rice.  Other crops such as soybean that have been planted late may need herbicide sprays next to rice that has reached the reproductive stage.  Drift onto rice at this stage has a much greater chance of causing a significant yield impact.

This week over 75% of rice in the state should be at or approaching internode elongation (Table 1).  Acres that were seemingly behind the past couple of weeks have made a major push with the arrival of hot, sunny days.  The 4th of July holiday should begin the first push of rice heading in the state (Table 2) and with it, rice stink bug problems.  Plenty of stink bugs can be seen on headed grasses in and around fields – get ready.

 

Enroll fields in the DD50 Program here:    http://DD50.uaex.edu.

Problems or questions: jhardke@uaex.edu / 501-772-1714.

 

Table 1.  Percent of rice acres set to reach internode elongation during listed weeks of 2014 according to DD50 enrollment.

Internode Date Percent
Reached IE 76%
June 29 – July 5 19%
July 6-12 4%
July 13-19 1%
July 20-26 0%

 

Table 2.  Percent of rice acres set to reach 50% heading during listed weeks of 2014 according to DD50 enrollment.

Heading Date Percent
July 5-11 7%
July 12-18 38%
July 19-25 41%
July 26 – Aug 1 10%
Aug 2-8 3%
Aug 9-15 1%

 

Picture 1. Fall armyworms in rice.

Picture 1. Fall armyworms in rice.

Out Standing in Your Field

Reminder on use of 2,4-D

Last year restrictions were eased on the use of 2,4-D to allow use of this product to control weeds on RICE LEVEES ONLY in northern counties.  All other restrictions still apply.  Do not infringe on the other restrictions in place for 2,4-D.  Although levee applications are allowed, you must still adhere to restrictions regarding distances and wind to sensitive species that were in place in addition to the overall ban.  If these changes result in abuse of the system, the restrictions could be put back in place.  In all situations, check product restrictions and labels before you spray.  For more information please visit the Arkansas State Plant Board website.

Picture 2. 2,4-D allowed for weed control on rice levees.

Picture 2. 2,4-D allowed for weed control on rice levees.

Disease Update

It is now time to start scouting for sheath blight, leaf blast, and autumn decline in rice.  Although not extensive, sheath blight activity has been reported.  Similarly, leaf blast has been reported this week in Lonoke, Prairie, and Randolph Counties.  There are also some indications of autumn decline in a couple of fields as well.

Sheath blight is caused by a soil-borne pathogen.  The sheath blight pathogen structures do not move around very far compared to blast pathogen spores.  Farm equipment sometimes moves the pathogen from field to field.  Regardless of the pathogen’s limited movement, sheath blight is the most prevalent disease that may occur every year in any field if conditions are favorable.  The same pathogen causes aerial blight in soybean and infects other crops, grasses, and weeds.

The recent weather appears favorable for pathogen development and growth.  Sheath blight has already started showing up within six days after inoculation at experimental fields at Stuttgart.  Soil surviving pathogen structures referred to as “sclerotia” float on floodwater and start the infection process.  The disease progresses vertically to the height of the plant and horizontally through leaf or plant-to-plant contact.  The disease is favored by thick canopy, excessive nitrogen, and warm and humid (moist) conditions.  When scouting for sheath blight, open the canopy and look for lesions close to the water level and up (Picture 3).

Picture 3. Sheath blight lesions on rice.

Picture 3. Sheath blight lesions on rice.

To read more on scouting, management options, and fungicide use go to:  http://www.arkansas-crops.com/2013/06/10/scout-for-sheath-blight-disease-of-rice-from-green-ring-until-pre-heading/ and http://www.arkansas-crops.com/2014/05/27/pointers-blight-management/.

This week, leaf blast has been reported and confirmed on Jupiter in Lonoke and Randolph Counties.  To read more on this week’s blast situation and its management go to:  http://www.arkansas-crops.com/2014/06/26/disease-reported-arkansas/.

 

Picture 4. Shade from tree line elongates dew periods and makes favorable environment for blast fungus.

Picture 4. Shade from tree line elongates dew periods and makes favorable environment for blast fungus.

Picture 5. Distinct sporulating lesions formed by blast fungus help diagnosis.

Picture 5. Distinct sporulating lesions formed by blast fungus help diagnosis.

Picture 6. Young blast lesions can be confused with brown spot or chemical injury.

Picture 6. Young blast lesions can be confused with brown spot or chemical injury.

Picture 7. Drought stress or aerobic conditions encourage blast development.

Picture 7. Drought stress or aerobic conditions encourage blast development.

A few fields have also started showing black root rot which is also referred to as autumn decline or hydrogen sulfide toxicity or Akiochi.  To read more on autumn decline and how to scout and its management go to:  http://www.arkansas-crops.com/2013/05/23/weather-and-akiochi-disease-of-rice-is-there-a-link/ and http://www.arkansas-crops.com/2014/03/20/effectively-decline-straighthead/.

Picture 8. In severe situations, most roots turn black and rot, the root system shuts off and crop growth slows down and could die unless managed properly and timely.

Picture 8. In severe situations, most roots turn black and rot, the root system shuts off and crop growth slows down and could die unless managed properly and timely.

DD50 Enrollment

Some changes have been made to the online DD50 Program this year.  Hopefully these and future changes will continue to make the program easier and more efficient to use.  If you have any questions, or suggestions for improving the program, please let us know.  You can access the online program here: http://DD50.uaex.edu/.

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 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.

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