August 3, 2013 No. 2013-19
Dr. Jarrod Hardke, Dr. Gus Lorenz, and Dr. Yeshi Wamishe
While there have been a few reports of fields just going to flood in the last couple of weeks, the state is about 40% headed to date. DD50 numbers indicate that nearly 80% of fields should be at 50% heading now. I’ll continue to remind – don’t be surprised if your DD50 estimates are 5-7 days off at this point. The May cold spell threw one big monkey wrench in our heat unit data because of the unpredictable plant response to the cold.
We continue to slip later based on recent weather. Our cooler than normal temps (day and night) have certainly had something to do with that. Some have noted that it has also been cloudier than usual. The answer is yes, this can have an effect on the accumulation of heat units. I would say that not all heat units are created equal and that I believe light intensity can have an impact on them. You tell me – do you accumulate more heat on a cloudy day or a sunny day?
In fields still not headed, keep an eye out for sheath blight. While we are not receiving the increase in reports of this disease we expected to be associated with the rain and cool temps, it is still moving up the canopy in some fields. Remember the threshold – 35% positive stops in susceptible/very susceptible cultivars, 50% positive stops in moderately susceptible cultivars. In fields that are headed, continue scouting for rice stink bug.
Tables – Percent of rice acres to reach growth stages during listed weeks of 2013 according to current DD50 enrollment.
|Table 1. 50% Heading||Table 2. 20% Grain Moisture|
|50% Heading Date||Percent||Harvest Date||Percent|
|50% Headed||78%||Aug 3-9||0%|
|Aug 2-8||13%||Aug 10-16||0%|
|Aug 9-15||6%||Aug 17-23||18%|
|Aug 16-22||2%||Aug 24-30||25%|
|Aug 23-29||1%||Aug 31 – Sept 6||28%|
|Sept 8 – Oct 4||1%|
Out Standing in Your Rice Field
Rice Stink Bug
The more fields that begin to head, the lower the reports of rice stink bug numbers. We are spaced out enough to prevent us from spreading them out to below threshold at this point, but finding 5-10 per ten sweeps is better than 50+. What does 90% control of 50 stink bugs leave you with – 5 stink bugs and another treatment needed.
There have been plenty of questions coming in about fields that are heading unevenly due to the abnormal weather right now. What if my field is only 20% headed and I don’t think I’ll hit 50% over the rest of it for 5-7 days? It depends on how high your stink bug populations are to make a smart decision. If you have a 100 acre field and only 20 acres is headed, can you accept some yield loss on that 20? Or is the yield loss going to be enough to warrant spraying the entire 100 acre field to protect those 20 acres? If numbers are fairly low (5-10 per 10 sweeps), you still need to spray but can wait a few days for more rice to head. If you have higher numbers (20+ per 10 sweeps), you need to be more aggressive and spray sooner.
The nighttime temperatures have not reached high enough to be concerned about bacterial panicle blight. However, we cannot predict what will happen to fields with very late rice.
Most fields have received an application of a fungicide for suppression of kernel and false smut. We hope fields with adequate levels of nitrogen fertilizer (and other nutrients) will do well. Potassium is known to influence crop yield potential and plant susceptibility to various diseases.
Leaf blast has been reported on CL261 along a tree line in Monroe County. This field is right across from where leaf blast was reported a few weeks ago.
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.
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