May 30, 2014 No. 2014-12
Dr. Jarrod Hardke, Dr. Gus Lorenz, and Dr. Bob Scott
Most acres were probably in need of a rain, but maybe not the weeklong rain we have going on now. It’s not over yet with more rain forecast through the weekend. On a positive note, most of the rainfall has come slowly making it much easier to deal with than receiving it all at once.
It may be selling it short, but probably 10% of acres have gone to permanent flood to date. Many more acres were on the verge of being ready as this rain system approached, but were perhaps just a little too early. The short window to make both preflood herbicide applications and preflood nitrogen applications also likely led to some deciding to wait until this system passed by to move forward. The rain and previous cold weather delaying growth are responsible for the difference between the current estimate and the projection in Table 1. A big jump in flooded acreage will occur next week if we can get the ground dry enough to fertilize.
The official planted acreage percent as of Tuesday was 95%. With the duration of rainfall, and the amounts received, that 95% may now be 100%. We’ll be almost a full week into June before a lot of ground would be dried back out enough to plant more rice, meaning that rice may no longer be the most appealing option.
Figure 1 shows the updated planting progress for 2014 (black line) compared to previous years. The report for last week moved planted acreage to 95% which is above the 5-year average of 92%. Crop emergence is currently at 86%.
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Table 1. Percent of rice acres set to go to flood during listed weeks of 2014 according to current DD50 enrollment.
|May 29 – June 4||41%|
Out Standing in Your Field
We’re not certain what set of conditions seem to cause it, but sometimes we do see injury to Clearfield hybrid rice when ALS herbicides are applied (Newpath, Clearpath, Permit) (Picture 1). Ultimately it is probably the result of some stress on the plants (i.e. cool temps). Whether that stress is obvious or not, the immediate remedy is to remove any stress you can. In many cases that involves lowering the flood. “Lower” the flood does not mean “remove” the flood. We don’t want to lose preflood nitrogen, but a lower flood depth will reduce stress on injured rice. Similar symptoms can be observed on Clearfield varieties when using high rates and combinations of ALS herbicides.
Paraquat (Gramoxone) drift on rice can be seen in Picture 2. Note the localized injury is not translocated to the newly emerging leaf. The rice, while injured and possibly delayed as a result, will be fine.
Rice Water Weevils
We know rice water weevils are active now, and we’re beginning to see leaf scarring on rice where there is standing water and flooding. In some places scarring is extensive. As we start to establish permanent floods in fields, it’s time to be on the lookout.
If your seed was treated with an insecticide seed treatment (Cruiser, NipsIt, Dermacor) then you’re probably OK, but still need to monitor. If you didn’t use an insecticide seed treatment, then start scouting immediately after flood. Base treatment decisions on 50-60% scarring on NEW leaves – at this point you’re probably at threshold. Timing is critical if you’re going to take action – consider a foliar application of a pyrethroid within 5-7 days of flood establishment. After 7 days, don’t bother spraying, you’ve missed the window.
If you have rice planted >40 days ago, do not expect that you will have insect control from a seed treatment. Some rice that was planted in late March is just now going to flood – meaning it has been in the ground for about 60 days. Unfortunately, 35-40 days after planting is about the maximum length of time we can expect to get rice water weevil control from our seed treatments. If your rice has been in the ground for longer than that, be prepared to scout and possibly spray if needed.
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.