Rice - Red Rice Control Red Rice has been a weed problem in much of the rice-growing area for a number of years. Recently, as rice acreage has expanded in Mississippi, red rice has become an even more serious weed problem. Botanically, red rice is the same species as cultivated rice, Oryza sativa (L.). It is actually a variety of rice. It reproduces itself and does not come from rice varieties genetically "running out." Red rice is difficult to control in rice and is a strong competitor, thus reducing yields. Yield is reduced in proportion to the infestation. An extremely heavy infestation of red rice can reduce yields nearly 100 percent. Red rice plants vary considerably. The tall-growing, black-hulled, awned plant is easiest to recognize and is considered by many to be a typical red rice plant. However, other strains have developed that have straw-colored hulls, are awnless, and are about the same height as desirable rice varieties. This type of red rice is the most prevalent kind in Mississippi. Red rice has camouflaged itself well. Usually, the red rice seed is shorter and wider than long-grain rice; therefore, much of the red rice seed can be removed by seed-processing equipment. But in the last few years, a long-grain red rice has appeared that cannot be removed by processing. This possibly is a result of some natural crossing that has occurred in the field. It is difficult to recognize this type of red rice in the field because of similarity in height, hull color, and grain shape. Since it is the same species as desirable rice, chemical control of red rice in rice fields is important at this time, but research with selective grass herbicides indicates control may be possible by preventing seed-head production. For now, other means of control must be used. Select Seed Source Carefully Red rice infestations occur primarily through planting contaminated seed and through combine contamination. If combines are not thoroughly cleaned after harvesting a red-rice-infested field, they can contaminate later-harvested, noninfested fields. Be careful of seed sources to be sure the seed you are buying does not contain red rice. Most pure seed laws permit some red rice in rice seed; certified plantings are more restrictive. The Mississippi Seed Law allows up to nine red rice seed per pound of rice seed, but no red rice seed can be present in any class of certified seed. Seed bought directly from farmers does not have to meet state regulations, so this seed could contain anything the farmer chooses to sell. Be sure to check your seed source and plant on fields that are free of red rice if possible. Since most red rice shatters before harvest, almost all the seed produced remains in the field. This results in heavy red rice stands and reduced yields the following year. Red rice seed can remain dormant in the soil up to five years, making eradication difficult and requiring rotational crops to reduce infestations. Chemical and Cultural Control Practices Management is the key to controlling red rice and reducing its competition with rice yields. Here are some control measures that can reduce the red rice problem: Begin a combination of crop rotation with soybeans or sorghum (preferably, two years soybean--one year rice). Control red rice plants in field borders. Rogue any plants missed by chemicals. The control program must be designed for 100 percent control. Control is almost impossible while a field is planted to rice. Fall plowing of clay soils following rice harvest is difficult at best. However, if it can be done, a flush of rice seed germination will occur, and winter freezes will kill these seedlings. Early land preparation before planting the rotation crop will produce another red rice seed germination flush that can be killed by preplant disking and the planting operation. Most Mississippi rice soils are clay soils with higher than normal organic matter content. Effective control in rotational crops for soil-applied herbicides requires from one to two times the normal herbicide rate. Also, a single soil herbicide application seldom provides season-long control since germination occurs throughout the summer. Most soil herbicides provide effective control for two to three months. Make postemergence herbicide applications as needed to control escaped plants. Chemical Control Programs Based on Three-Year Rotation Soybeans as Rotational Crop Year 1 -- Soybeans (planted in rows wide enough to cultivate) Preplant Incorporated: Treflan 2X or Dual--These chemicals should be tank mixed with Sencor/Lexone to improve the control of red rice and broadleaf weeds. (Some suppression of red rice on clay and silt loam soils can be obtained with Lasso.) Postemergence: Multiple applications necessary Postdirected: Paraquat + nonionic surfactant 2 applications -- when soybeans are at least 8 inches tall. Make first application before red rice is 3 inches tall, followed by second application 7-10 days later. Over-the-top applications (semi-direct to obtain maximum coverage of red rice seedlings in the soybean drill) Assure II + nonionic surfactant or crop oil concentrate. Apply to red rice up to 4 inches tall. Repeat application to newly emerged plants when needed. Do not use vegetable (crop origin) oils as spray adjuvents or carrier with Assure II. Select + crop oil concentrate. Apply to red rice up to three inches tall. Repeat application to newly emerged plants when needed. Year 2 -- Soybeans Preplant Incorporated: Dual--Tank mix with Sencor/Lexone to improve the control of red rice and broadleaf weeds. Some suppression of red rice on clay and silt loam soils can be obtained with Lasso. Postemergence: Same as Year 1 Further control measures in soybeans to be used in conjunction with ppi and multiple postemergence applications include: Mechanical Cultivation--multiple shallow tillage operations in early spring or fall. Use of a smoothing device in conjunction with a tillage tool further stimulates red rice germination. Prevention--clean all machinery when moving from infested to noninfested fields. Hand Rogue--remove the entire red rice plant. Parts of the rice plant not removed can still produce viable seed. Year 3 -- Rice (no chemical control in dry-seeded rice). For better red rice control, rice can be water seeded using the pinpoint seeding method. If this method will be used, refer to the water seeding section of this publication for instructions. Further control measures in rice include: Mechanical Cultivation--same as soybeans. Prevention--clean all machinery; purchase red rice free planting seed; when land leveling, avoid moving soil from red rice-infested to noninfested areas; avoid using drainage ditches that may contain red rice. Hand Rogue--remove the entire red rice plant. Parts of the rice plant not removed can still produce viable seed. Grain Sorghum as Rotational Crop Grain sorghum can be used as the rotational crop for one or both years of the two-year rotation. Purchase seed that are treated with Concep or Screen and incorporate either Dual or Lasso before planting. Apply atrazine either preemergence or early postemergence. Paraquat can then be used once or twice as a postdirected spray to control escaped plants, beginning when sorghum is 12 inches tall. If grain sorghum is planted the second year of the rotation Atrazine cannot be used because of its residual label restriction. By Dr. Ted Miller, Extension Agronomist, and Dr. Wayne Houston, Extension Leader, Agronomy Mississippi State University does not discriminate on the basis of race, color, religion, national origin, sex, age, disability, or veteran status. Information Sheet 930 Extension Service of Mississippi State University, cooperating with U.S. Department of Agriculture. Published in furtherance of Acts of Congress, May 8 and June 30, 1914. Ronald A. Brown, Director Copyright by Mississippi State University. All rights reserved. This document may be copied and distributed for nonprofit educational purposes provided that credit is given to the Mississippi State University Extension Service. Visit: DAFVM || USDA Search our Site || Need more information about this subject? Last Modified: Wednesday, 11-Feb-09 14:06:31 URL: http://msucares.com/pubs/infosheets/is0930.htm Mississippi State University is an equal opportunity institution. 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