Friday, October 8, 2010

The 2010 Rice Crop - A Look Back

The 2010 rice crop is near completion with over 90% of the rice harvested. Yields have been less many growers anticipated and in several cases, a failure. While yields for a few growers were actually better than ever, most struggled with yields typically ranging 20-40 bushels/acre less than normal. The number of failures that I have been involved with (less than 120 bushels per acre is really a failure in today’s economic environment) have exceeded what I have experienced in the past 20 years. The USDA has estimated Arkansas yields at 142 bu/acre, which is the lowest statewide yields we have had since 2001.

As you look back and try to prevent these disasters from happening again, here are just a few observations. The heat was certain a factor but, in and of itself, was only partially responsible for lower yields.

Water management proved to be crucial. The heat and drought strained the irrigation abilities of many growers and ultimately caused significant yield losses. Hot spots or areas where water never reached were evident in many fields across the state.

Bacterial panicle blight was widespread and responsible for major losses among certain varieties. This disease was particularly more severe in fields of rice following rice and later planted.

Planting date had a significant effect, as it normally does. However, the date at which yields began to be negatively impacted was much earlier than normal. Because we experienced the heat so early in the growing season that “late planted rice” was most everything planted after April 20.

Low fertility, particularly potassium, was observed in an alarming number of fields. These fields with inadequate fertility often expressed their effects as stem rot, cercospera (narrow brown leaf spot), and to a limited extent bacterial panicle blight.

Excessive rainfall early in the growing season resulted in severe flooding in some areas. Rice was submerged in some areas for an extended period of time and the yields were affected.
Many of these problems will solve themselves if we can avoid record high night-time temperatures and season-long drought. (Much of the state is still in a mild drought). I am certainly ready to put 2010 down as one of the most difficult in the last 25 years and move on to 2011.


Harvest of the 2010 Arkansas Rice Performance Trials has been completed and the yields have been compiled. Preliminary yield results can be downloaded from the Arkansas Variety Testing website ( I caution that these yields are preliminary and will not be final until complete review. The final report should be completed soon and will be available as a Rice Information Sheet either online at the above web site, at the University of Arkansas Cooperative Extension Service website, or in printed form from you local County Extension Office. The hard copies should be available in January, 2011.

Thursday, September 9, 2010


"The field looked good all year but the rice just isn't there.  What happened?"  After the earliest rice fields were harvested during the first two to three weeks of August, we started hearing this question more and more and recently (last week of August to September 8), more and more fields have been affected.

The following is some of what we have observed in trying to figure out why particular fields are yielding lower than expected.

HEAT – This year has had the highest average temperatures of any summer on record, surpassing 1980. While the day temperatures have been hot, the night temperatures have been the reason for setting a new record. Any year where we have day and night time temperatures as hot as we experienced in June and July, yields and milling quality suffer. The earliest planted rice fields are the least affected and this is true this year and all varieties and hybrids seem susceptible. This does not explain why one field yields well and others around it yield poorly, though. Especially when the fields are planted and managed the same.

WATER MANAGEMENT – When we have day time temperatures of near 100 degrees and night temperatures in the 80’s day after day, and no rain for weeks, establishing and maintaining a flood is extremely difficult. I know guys don't want to hear that they may have water management problems, but... 
It was evident in several fields this year that “hot spots” were developing because the well could not keep up with the demand for water by the rice plant. Also, don’t forget that several fields never saw the first flood until close to midseason. With this heat, we have also observed fields where the flood was simply drained too early and the result was that grain fill was interrupted and yield was off. High spots or later maturing areas of these fields were most affected, as well as the bottom part of panicles on secondary tillers. There also seems to have been some cooling effects observed by well water compared to surface water, which has resulted in higher yields in some cases.

BACTERIAL PANICLE BLIGHT (or panicle blight)- In years where night temperatures are high, like this year, or 1993, 1995, 1998, 2001 etc – we see a lot of problems with this disease. Typically we called this “Bengal” disease because it mostly affected the medium grain variety Bengal over the years. However, it really hot years, the disease developed in long grain fields as well, and heavily damaged Cypress (for example) in 1995 and we have seen it hurt Francis, Cocodrie, Cheniere, Wells and other varieties at times. For whatever reason, it does not appear to affect hybrids and Jupiter (released as partially resistant) does not seem to be susceptible under our conditions.

This year, we have observed bacterial panicle blight in CL 151, CL 111, CL 131, Wells, Francis, Neptune, CL 142AR, CL 261 and Cheniere. Factors associated with the worst fields have been:

rice after rice rotation;
not enough potassium fertilizer;
too much nitrogen fertilizer;
heavy stinkbug pressure;
excessively high seeding rates.

Yield losses up to 50% have been estimated for some fields and this disease appears to be widespread in the state during 2010.

CL 151 field with heavy bacterial panicle blight

Close-up of affected panicles

Close-up of bacterial panicle blight at a more advanced stage on Bengal rice

NARROW BROWN LEAF SPOT AND BROWN SPOT DISEASE – For whatever reason, we are seeing more damage from these two diseases than in previous years, mainly to the panicles and flag leaves in affected fields. Both can cause lesions within the panicle, blanking out spikelets and individual kernels, and on some fields doing heavy damage to the flag leaves. Damage has been observed on several varieties including CL 151, CL 111, CL 131, CL 261, Cheniere (and probably others) as well as the hybrids. Factors associated with fields having the most disease include not enough potassium fertilizer; rice after rice rotation; and later planting dates.

Close-up of narrow brown leaf spot infecting panicle of rice
(resembles blast sometimes and brown spot can cause this also)

STRAIGHTHEAD – We have observed and had more reports of true straighthead than normal. This is an old disease of rice in the state, associated with certain fields. Dark green, normal sized leaves and stems, with blanked and distorted kernels only in the flooded paddies (not on levees) would be typical symptoms. However, some long grain rice varieties including Cocodrie, do not display a lot of parrot-beaking in the kernels but usually you can find some if you look hard enough. Medium grain varieties are more likely to show a lot of parrot-beaking, in our experience. Straighthead occurs each year in susceptible fields when rice is planted and the flood is not drained at the proper time to prevent the disease. Some fields this year that have reported straighthead symptoms have no history of the disease, so in these cases, we would be suspicious that you may be dealing with something else. We have had a lot of calls on Cheniere this year, and have observed some fields with symptoms, and we are not sure what is going on because in the past Cheniere has been pretty resistant to true straighthead in Arkansas. In the fields where we have seen what appears to be true straighthead on Cheniere, the variety does not look exactly like the Cheniere we have evaluated in the past. And these fields have had neck blast scattered across the same fields, another disease that Cheniere has not had a problem with in the past under our conditions.

Straighthead on Cocodrie, note little parrot-beaking

Severe parrot-beaking on a different rice variety, note full size leaf

STINKBUGS – It seems to have been a record stinkbug year, and many fields we have been in have the “odor” of heavy stinkbug pressure. In many cases, 2 or 3 applications of insecticides were made to try to control this insect. However, in some fields, there was still damage including blanking and pecky rice. We suspect an association with this insect, and possibly other arthropods on rice, and bacterial panicle blight but have no conclusive proof of this. It just seems the disease is worse in fields with high populations of stinkbugs. Regardless, we should not underestimate the direct and indirect effect of this insect on yield and quality in rice this year.

GLYPHOSATE DAMAGE – We planted most of our rice early this year, but planted most glyphosate resistant soybeans later than normal. This lined up drift problems to rice in certain areas of the state again, and we have walked a number of fields thought to have straighthead that actually were damaged by late glyphosate drift when the rice was at a sensitive stage. Glyphosate causes parrot-beaking and other distortions and blanking of the kernels, and depending on the growth stage when drift occurred may cause shortening and distortion of the flag leaf, or at least distortion and a leathery feel to the base of the upper leaves. Yield loss can be heavy and affected plants can be found in flooded paddies or on levees, unlike straighthead, and usually there is an association with the source of the drift – a nearby glyphosate resistant soybean or cotton field, etc.

Severe glyphosate injury to rice
(symptom severity varies a lot in affected fields)

STEM AND SHEATH DISEASES – We have been in a number of fields damaged by stem rot this year, a disease that seems to like hot summers. It also likes low potassium and rice after rice, so fields that have not been fertilized or rotated properly have the most damage. Symptoms include lodging and stem lesions, as well as blanking of the base of panicles on affected tillers. Other stem diseases can cause some of this as well, and we have observed several fields of hybrid rice where black sheath rot (crown sheath rot) and possibly other sheath diseases have weakened the lower stems – causing lodging - and blanked out some kernels.

Lower potassium field with lodging caused by stem and sheath diseases


Wednesday, August 11, 2010

Rice Stink Bug Alert!

(Dr. Gus Lorenz)
We are observing large numbers of stink bugs moving into rice fields that are in the 3rd and 4th week of heading. We are observing numbers as high as 4x threshold. This is occurring in all rice growing regions

of the state. These are fields where the rice panicles/ seed are in the milk or soft dough stage. Stink bug feeding at this time can cause "pecky rice", which can result in significant discounts on the price received when the rice is sold.

Rice is not safe from damage until it reaches the hard dough stage. If the rice grain is still soft and pliable or can be squeezed between your fingers, it is still susceptible to damage. In many cases the oldest part of the panicle is hard dough but the base of the panicle is still soft dough. This is a field-by-field call. Just remember the discount for peck can be severe and best avoided.

The threshold for rice stink bugs is one per sweep. Take 10 sweeps in several locations in the field if you are averaging 10 stink bugs per 10 sweeps you need to make an insecticide application. Recommended products are pyrethroids such as Karate or Mustang Max or methyl parathion. Do not release the flood water within 7 days of application. Also be advised that when sampling during the hot part if the day, stink bugs move down in the plant and sampling at this time may not reflect the true number of stink bugs. Sampling is most effective early in the morning and late in the evening when the bugs are out on the panicles. Sweepnets are much more effective than "visual observations".

Thursday, August 5, 2010


The University of Arkansas Rice Research and Extension Center will host its annual Rice Field Day on Wednesday, August 11, 2010 beginning at 7:30 am. There will be one field tour with departure times of 7:30, 8:00, 8:30, and 9:00 am. Topics on the tour include hybrid rice breeding, nitrogen soil test for rice, soybean production, rice weed management, rice disease management, and new rice varieties. Come and see our new laboratory and office facility and check out new technology in rice.

Is it time to drain my rice yet?

I realize that several farmers have already started draining, and even harvesting in some cases. However, I thought this might be helpful in light of the heat and drought conditions we are currently experiencing. Farmers are always interested in when I can quite spending money on irrigation and begin to prepare for harvest. This has been especially true this year in light of the high input costs already paid out for this crop. For the majority of the rice acreage, we recommend draining 25-28 days after 50% heading. This generally corresponds to the time when the heads have all turned down and most of the panicles have changed color at least half way down the panicle. The photos below illustrate what rice typically looks like 25 days after 50% heading. The three panicles in the second photograph were taken from the plot in the first photograph.

Research varies on the effects of earlier draining but some studies have reported yield losses as much as 10% when drained too early. Remember in this heat, soils dry quickly. Don’t over estimate the amount of time is will take for the soils to dry. One option to help reduce pumping costs is to establish a good flood 14 days after 50% heading and then let the field dry down. This works for some growers but others have indicated that removing levee gates is too difficult if the fields dry out before drain time. In hot, dry years like this year, you still may need to flush through the fields if you don’t get any rainfall to help the crop to mature. If you routinely must rut the field in order to get the rice harvested on time because the fields do not dry enough, earlier draining is a feasible option. This is usually the case on most heavy clay fields.


Sodium chlorate is commonly used to desiccate green foliage and weeds present in rice fields to increase harvest efficiency. The general guidelines are to apply sodium chlorate at 3 to 6 pounds a.i. per acre when rice grain is near 25 percent moisture and harvest within 3 to 7 days after application. Although sodium chlorate is typically used to dessicate the vegetation, grain moisture is also reduced. Research suggests that when used properly sodium chlorate does not reduce head rice yield. However, application of sodium chlorate at 6 pounds a.i. per acre significantly reduced grain moisture by 2 to 5 percent within four days after application. Head rice yields may decline if grain moisture drops below 15 percent before the grain is harvested. Thus, sodium chlorate should be applied to rice that is between 18 and 25 percent moisture with timely harvest following application. Use of sodium chlorate on seed production fields is sometimes needed. Research has shown that sodium chlorate does not influence germination of the resulting seed.

Desiccation of rice foliage is noticeable within 36 hours after application, especially when temperatures are high. The photo above was taken less than 48 hours after application.  The treated plots are very apparent and dessication was very effective. Sodium chlorate may reduce head rice and grain yield if applied too early, before grain fill is complete. Do not apply to rice when the moisture is above 25%. Growers should exercise caution when considering sodium chlorate application to fields with uneven maturity to avoid yield and quality losses.