Dr. Jarrod Hardke
July 15, 2016 No. 2016-18 www.uaex.edu/rice
It’s always an exciting time of year as rice starts heading. Sure we have rice stink bug issues to worry with right now, but the end is now in sight.
By the end of the weekend we should have reached or be past 50% heading on nearly 70% of our fields (Table 1). As more rice fields head out, the stink bug numbers are declining. Treatments are being made and that will certainly help the number to keep falling. With any luck we’ll get away with a single application on most fields.
Table 1. Percent of Acres at 50% Heading by Week Based on DD50 Enrollment.
A welcome sight lately has been the cooler than expected nighttime temperatures. While many of the metropolitan area forecasts and temperature readings have shown some high numbers, weather station data from sites in the Delta don’t support it (Table 2). It seems that even though it’s been pretty hot to us lately, it hasn’t been so hot that grain quality should be affected.
Having said that – once again it appears there are extreme high temperatures in our forecast. We’ll see if it holds true this time. Hopefully not but it would likely bring some high nighttime temperatures at the wrong time for many.
Table 2. Recorded Daytime & Nighttime Temperatures (°F) at AR Weather Stations.
Fig. 1. Heading under favorable conditions.
Rice stink bug (RSB) thresholds are:
- 5 RSB per 10 sweeps the 1st 2 weeks after 50% heading.
- 10 RSB per 10 sweeps the 2nd 2 weeks after 50% heading.
Drain Time Approaching Rapidly
With heading for many fields in full swing it will be time to drain fields before we know it. As we all know ‘draining season’ is a time for celebration – work, but celebration. Before we get in too big a hurry to celebrate, let’s try to make sure we get it right.
The basic recommendations for draining are 25 days after 50% heading on long-grain cultivars and 30 days for medium-grain cultivars. These are the number of days built into the DD50 program.
However, depending on temperatures, rainfall, and overall environmental conditions, drain timing is a moving target. As a result, drain timing is as much an art as a science.
Fig. 2 shows a general guide for determining relative grain maturity. In the figure: at left nearly all kernels are straw colored (field is safe to drain regardless of soil type); at center nearly 2/3 of kernels are straw colored and it is safe to drain on a silt loam soil; and at right 1/3 of kernels are straw colored and would be close to safe drain timing on a clay soil.
When choosing when to drain – always edge on the side of caution. Draining too early can sacrifice some late grain fill and hurt yield. Use a combination of the days after 50% heading guideline (25-30 days) and the relative grain maturity in the field to make your drain decisions.
Fig. 2. Rice panicles at different maturity levels described by percent straw color:
(L) 100%, (C) 67%, and (R) 33%.
Fig. 3. Late season sulfur deficiency. No yield recovery possible this late.
Fig. 4. Environmental damage to kernels – likely due to daytime winds.
Arkansas Rice Expo is August 10th
The 2016 Arkansas Rice Expo will be held at the Grand Prairie Center in Stuttgart, AR on Wednesday, Aug. 10.
More details to follow.
The DD50 program can be found at http://DD50.uaex.edu. Enroll fields now to help with timing most major rice management practices.
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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.