June 13, 2014 No. 2014-14
Dr. Jarrod Hardke, Dr. Rick Norman, and Dr. Bob Scott
Progress? What progress? We’ve been in a standstill. A rare June rainy season standstill. I don’t believe I ever thought I’d say that.
The recurring theme has been that it’s raining and supposed to continue to rain. Days without rainfall have been the exception rather than the rule.
Yesterday delivered quite the disappointing rain for much of the northern half of the state. Some locations received 2+ inches of rain in less than an hour. The southern half of the state didn’t escape the rain, but it did receive lighter amounts. The good news? Yes, there is finally some good news. Nothing above minimal rain chances for the next 10 days. Some may feel the dry spell will be too little, too late. That may or may not be true. Delayed fields where we have gotten nitrogen out in some form or fashion, while not ideal, can be managed and will be alright.
This week 87% of rice in the state should be fertilized and flooded (Table 1). In reality, most of it may be flooded, but not on purpose. We’re now one week closer to rice reaching beginning internode elongation (Table 2). In fact, some early-maturing cultivars that were planted early already have some internode elongation (joint movement) occurring and no nitrogen has been applied.
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Table 1. Percent of rice acres set to reach permanent flooding during listed weeks of 2014 according to current DD50 enrollment.
Table 2. Percent of rice acres set to reach internode elongation during listed weeks of 2014 according to DD50 enrollment.
|June 29 – July 5||16%|
Running Out of Time for Herbicides
A number of fields are starting to hit or are fast approaching beginning internode elongation (green ring, joint movement). When we reach this stage, there are several herbicides which are no longer options for cleaning up some of our messes out there. Beyond, Regiment, and 2,4-D cannot be applied past green ring. Newpath cannot be applied post-flood (recommended time for last application is 3-5 leaf rice).
More on Preflood Nitrogen Management
The questions continue to come in about managing preflood N fertilizer applications in difficult situations. Just a reminder, even if you feel you will be a little late, it is still better to flood in your fertilizer on dry ground. With yesterday’s rain, the fastest way to get this done will likely be to fly N on mud and let the soil dry for a couple of days before starting the pumps.
You can see in Tables 3 & 4 how advantageous it is to flood in N on dry soil compared to muddy soil. Applying 60 lbs N/acre to dry soil (181 bu/acre) was similar to applying 120 lbs N/acre to muddy soil (174 bu/acre). This is the basis for strongly encouraging N applications to dry soil whenever possible. However, when time is our enemy, it becomes critical to get N out in some way so we don’t develop a deficiency that results in a significant yield reduction. Another reminder – don’t put out the preflood N in one single application into standing water.
Table 3. Influence of soil moisture and N rate on rice grain yields (bu/A).
|N Rate||Dry Soil||Muddy Soil|
Table 4. Influence of preflood N source and soil moisture on rice grain yields (bu/A).
|N Source||Dry Soil||Muddy Soil|
|Urea + NBPT||199||182|
* N source applied 3 days prior to permanent flood at 4-5 leaf stage.
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Out Standing in Your Field
The damaging straight-line winds that hit the state last week created plenty of serious problems. One less serious, but noticeable problem, was wind-damaged rice (Picture 1). It’s not a good thing, but ultimately the rice will be fine and grow on out of it.
In Picture 2, Roundup + Reflex + Dual was drifted onto rice. Looking at the plants a little closer, root symptomology was found that is similar to what you would expect to find with hydrogen sulfide toxicity (blackening) and/or delayed phytotoxicity syndrome (twisting roots and tillers). This particular situation is believed to be induced by the herbicide injury, but is a good reminder to take a good look at the roots whenever you have a problem in your rice field.
Newpath drift calls have picked up significantly in the past week. Continue to watch out for neighboring fields as the wind picks up. Remember that when Newpath drift occurs on conventional, non-Clearfield rice, it is best to dry the ground up to help the rice recover. That hasn’t been much of an option lately, but this coming week we should be able to do it.
Calls about suspected herbicide carryover from soybeans have also been common lately (Picture 3). This is obviously difficult to confirm and diagnose, and often other factors are at work that could lead to a crop response (fertility issues, salt, etc.). Stick to the label for plant-back intervals. When spraying soybeans that will be in rice next year, be careful about doubling and tripling up with different herbicides that are actually the same mode of action. This is never a good idea anyway, but it’s possible that applications of a lot of different products can generate a response even when used as recommended.
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/.
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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.