(Tables referenced on this webpage can be viewed by downloading the PDF of the publication.)

Soybean production guidelines are prepared by LSU AgCenter cooperating personnel from Louisiana Agricultural Experiment Station researchers and by Louisiana Cooperative Extension Service specialists.

Variety Selection

Variety selection is not a decision to be made lightly as it is the most important decision facing a producer going into the season. No other input can radically change the yield potential to the extent that variety selection can. This decision can be daunting, but through the LSU AgCenter, producers do have information at their disposal to improve this decision-making process.

Fortunately, growers in Louisiana have two types of multi-environment data to use when selecting varieties. The official variety trials (OVT) are small-plot trials where varieties are evaluated. For the 2024 OVT, 91 varieties were entered by 11 seed companies and two university soybean breeding programs. The varieties consisted of several different herbicide technologies, and the maturity groups (MG) range from 3.9 to 5.7. The trial was conducted at six research stations across the state in different soil types, including sandy loam, silt loam and silty clay loam.

In addition to the OVT, the LSU AgCenter collaborates with soybean producers to evaluate soybean varieties on farms. For these core-block demonstrations, LSU AgCenter parish agents cooperate with producers to plant, maintain and harvest strip trials submitted by seed companies. These demonstrations provide valuable yield data from local growing conditions and agronomic practices. The core-block program is designed to evaluate a select number of soybean varieties in large plots located across the state. In some cases, observations from these large plots can result in identification of varieties that are resistant to a number of soilborne maladies. Six seed companies submitted varieties for the 2024 core-block demonstrations. A total of 25 demonstrations were planted across 13 parishes. The demonstrations were divided by maturity group (MG). A demonstration consisted of varieties with a MG of 4.1 to 4.4, 4.5 to 4.9, or 5.0 to 5.5. The numbers of varieties submitted for each MG were six (MG 4.1 to 4.4), 11 (MG 4.5 to 4.9) and six (MG 5.0 to 5.5).

The OVT and the core-block demonstrations allow producers to select from the large number of varieties in the OVT and from varieties tested in environments similar to their farms. We would advise growers to make all variety decisions based on multienvironment and multiyear (when possible) data to identify stable varieties that perform well over a range of environments.

For best use of this guide, we recommend evaluating variety yield results based on performance and stability. Performance refers to identifying the varieties that are high yielding in environments that best represent your local farm. Stability refers to the performance of a variety across multiple environments. It is important for growers to consider both factors when making variety decisions.

2024 Soybean Core Block Parishes

Other Varietal Characteristics

Variety yield potential is an important trait in selecting a variety, but other varietal characteristics should also be considered. How these criteria rank in importance to the grower may vary from one grower to the next and may vary from one field to the next. Several of these criteria for variety selection are discussed below.

Herbicide Tolerance and Weed Management Programs

Six different herbicide tolerances are available in soybean in 2025. They are Roundup Ready, Enlist, Liberty Link and STS/BOLT. Both Xtend and XtendFlex soybean varieties will be available for purchase, but no dicamba formulation is currently registered for use; therefore, dicamba cannot be legally applied. Roundup Ready is tolerant to glyphosate; Enlist is tolerant to glyphosate, glufosinate and 2,4-D choline; Liberty Link is tolerant to glufosinate; STS/BOLT is tolerant to glyphosate and higher rates of Classic and other ALS-herbicides; Xtend is tolerant to glyphosate and Engenia, Tavium and XtendiMax; and XtendFlex is tolerant to glyphosate, glufosinate, and Engenia, Tavium, and XtendiMax. At the time of this publication, Engenia, Tavium and XtendiMax are not registered for use in Xtend or XtendFlex soybean. If multiple herbicide technologies are utilized by a producer, they should be careful in their planning because there is no cross tolerance among the varieties. Regardless of the herbicide-tolerant technology utilized, application of a residual herbicide prior to soybean emergence followed by a post-emergence application of a residual herbicide that is tank-mixed with a nonselective herbicide is the best strategy to manage herbicide-resistant weeds. For Enlist varieties, the company website should be consulted prior to mixing herbicides to ensure whether the desired herbicide combination is legal. Applications of Enlist One or Enlist Duo require specific spray nozzles; therefore, check the company website to ensure spray nozzles are legal. Research has shown that maintaining soybean weed-free for the first five weeks after emergence can maximize yield and the best program to accomplish this is use of residual herbicides preemergence and postemergence.

Disease Resistance

Soybean varieties differ in susceptibility to diseases and nematodes. Aerial blight is an important foliar disease south of Alexandria and is becoming more of an issue in northern parishes. Cercospora leaf blight is a major disease throughout the state. Frogeye leaf spot has been less of an issue in recent years because of resistant varieties but can be found annually. These, and other foliar diseases, may cause significant yield losses and harvest delays. Soilborne diseases may also be a problem in any given year. Sudden death syndrome (SDS) has been confirmed in Louisiana, but it is not widespread and is rarely seen. A soilborne disease with similar foliar symptoms as SDS known as taproot decline (TRD) has been confirmed by pathologists. Data from a specialized TRD variety trial is available in this publication. Phytophthora root rot is an isolated issue and is more prevalent in clay or poorly drained soils. Root-knot nematode is prevalent in sandy soils and is an annual problem in certain areas. When these and other diseases occur in official variety trials, ratings are conducted to identify potential sources of resistance, making variety selection the most economical way for producers to manage diseases. Specialized variety trials may be conducted in certain areas to target specific diseases, such as the taproot decline variety screening at Macon Ridge Research Station.

Insects

Soybeans are vulnerable to a range of insect pests including stink bugs (such as redbanded stink bug, brown stink bug, green stink bug and southern green stink bug), threecornered alfalfa hopper, beetles, Lepidopteran defoliators (such as soybean looper, velvetbean caterpillar and green cloverworm) and pod feeders (such as corn earworm/soybean podworm) from plant emergence until harvest. While soybean plants can withstand some level of insect injury, high insect pest populations can lead to severe yield reductions or even total crop loss. To reduce yield loss, fields should be scouted weekly using a sweep net, and appropriate control measures (e.g., insecticides) should be applied when action thresholds are met. Soybean varieties may vary in their ability to tolerate insect pests, less tolerant varieties should be scouted more frequently.

Scouting is particularly important for detecting the redbanded stink bug, the most damaging soybean pest in Louisiana. This insect pest feeds exclusively on legumes; thus, earlier maturing varieties are more vulnerable to redbanded stink bug damage. Generally, MG IV soybeans will have more damage than MG V at pod initiation, as seed set begins earlier and lasts longer. This results in longer exposure to stink bugs over time, resulting in greater opportunities for stink bug injury. Planting soybean as early as possible can help mitigate late-season damage. As early planted soybeans mature and are harvested, later planted soybeans act as a sponge and absorb all the surrounding stink bugs searching for a new host. As a rule, scouting for redbanded stink bugs should begin at R2 and occur every five days if possible. Failure to detect early populations can result in missed opportunities for control. As a reminder, the action threshold for the redbanded stink bug is 16 insects (nymphs and adults) per 100 sweeps.

For several years, we have screened high-yielding, commercially available soybean varieties for their susceptibility to stink bugs to provide information to agents, consultants and growers. Currently, no varieties offer immunity from stink bugs, but many commercial varieties yield very well under various growing conditions despite being susceptible to stink bugs.

Salt-Chloride Tolerance

Soybeans under continuous irrigation may be subjected to high levels of salts or chlorides from well or surface water. Observations from several years at the Macon Ridge Research Station near Winnsboro have made it possible to identify varieties that are tolerant or sensitive to salt-chloride. The problem shows up as leaf scorching and usually occurs shortly after irrigation water is applied. When choosing varieties to be utilized in irrigated systems, excluders (those varieties that can tolerate high chloride levels) should be chosen. However, yield potential of both excluders and includers (those varieties that cannot tolerate high chloride levels) will be reduced in soils with high chloride levels.

Maturity

There is a certain amount of overlap in maturity between groups within the state. Environmental conditions, especially drought and pest pressure, can cause variation in maturity. Most varieties within a group mature in the following range when planted at recommended times:

Where large acreages are involved, varieties of differing maturity should be selected to stagger the harvest and avoid losses from shattering and poor quality.

Lower Pod Height

Pod height is especially important in rough, poorly drained soils and new ground. It is important for all varieties to set pods a reasonable distance above the soil surface to aid in harvestability.

Poor Drainage

Many soybeans in Louisiana are planted on heavy clay soils with poor internal drainage. Research has determined that certain varieties are superior to others under these conditions. Planting on raised beds is desirable where drainage is less than optimal.

Lodging Resistance

Soybean varieties are more likely to lodge if a population of more than six plants per foot of row is present and if grown on a highly fertile soil. Tall varieties tend to lodge more severely than short ones. When lodging occurs, seed quality and yield are affected. A lodged field is more susceptible to disease and reduces harvest efficiency.

Plant Height

Plant height varies according to growing conditions, planting date, soil type and variety. If canopy closure has been a problem, a taller variety should be selected or a closer row spacing should be adopted. On highly fertile soil, too much growth is sometimes a problem, and a shorter variety is the better choice.

Seed Quality

Poor seed quality is more often found in early maturing varieties. Poor quality is especially true for indeterminate varieties that do not mature uniformly. However, in wet harvest seasons when temperatures and humidity remain high, seed quality issues can often be observed for most varieties. Poor seed quality occurs when fields are not harvested when ready or under heavy disease pressure. When poor conditions occur between physiological maturity (maximum dry matter accumulation) and harvest, chances increase for a decline in seed quality.

Cultural Practices

Lime and Molybdenum

Availability of most plant nutrients is typically greatest in soils with a pH of 5.8 to 7.0. When the soil pH drops below 5.2 on sandy loam and silt loam soils, and below 5.0 on clay soils, manganese toxicity may occur. When the soil pH drops below 5.0, aluminum toxicity may also occur. Soil testing should be conducted on a regular basis, and agricultural lime should be used to correct low pH soils to proper levels.

In extreme cases, manganese toxicity is expressed as a stunted plant with crinkled leaves. In milder cases, manganese toxicity may result in reduced yields even when visible symptoms are not present. Aluminum toxicity typically affects the roots, resulting in short, thick roots, a condition known as club root. Manganese and aluminum toxicities can be controlled by keeping the soil pH above critical levels.

Molybdenum is a critical component of the nitrogenase complex that fixes atmospheric nitrogen into a usable form for the soybean plant. Molybdenum is a nutrient needed by soybeans in small quantities. Although our soils typically have enough molybdenum for optimal growth, molybdenum is less available to plants as the soil becomes more acidic. At soil pH below 6.2, molybdenum should be applied as seed treatment at planting. However, if a commercial inoculum is needed and is applied as a seed treatment, molybdenum should not be applied as a seed treatment. The molybdenum salt will reduce the viability of the inoculum and will result in poor nodulation.

Nitrogen

Soybeans need large quantities of nitrogen. Soybeans remove about 4 pounds of nitrogen in each harvested bushel. Fortunately, soybeans are legumes and can obtain most of their nitrogen from the atmosphere. They accomplish this with the aid of the bacterium Rhizobium japonicum. These bacteria use soybean roots as a livable environment and form nodules on soybean roots that capture nitrogen from the atmosphere and fix it into a usable form. Seed should be inoculated with Rhizobium japonicum bacteria in soils with no recent history of soybeans or when conditions have reduced bacteria survival.

Phosphorus

Phosphorous is critical in the early stages of soybean growth. It stimulates root growth, is essential in the storage and transfer of energy throughout the plant and is an important component of several biochemicals that control plant growth and development. Phosphorus is concentrated in the seed and strongly affects seed formation. Soybeans remove about 0.8 of a pound of phosphate (P2O5) per bushel in the harvested portion of the crop.

Phosphorus deficiencies are not easily observed. Usually, no striking visual symptoms indicate phosphorus deficiency in soybeans. The most common characteristics of phosphorus-deficient soybean plants are stunted growth and reduced yields.

Phosphorus fertilization rates should be based on soil test results. Soil pH affects the availability of phosphorus, which is most available to soybeans when the soil pH is between 6.0 and 7.0.

Potassium

Potassium is essential in the growth and development of soybeans and is indirectly related to many plant cell functions. Some 60 enzymes require the presence of potassium, and plants with adequate amounts of potassium are better able to resist diseases than potassium-deficient plants. About four times as much potash (K2O) is required by soybeans as phosphate, (P2O5) and about twice as much potash (K2O) is removed in the seed as phosphate (P2O5). Soybeans remove about 1.4 pounds of potash (K2O) per bushel in the harvested portion of the plant.

Potassium deficiency symptoms are easy to diagnose when they are severe enough to be seen visually and will usually occur on the lower leaves during pod fill as margins (edges) of the leaves appear necrotic (dead and brown). Severe potassium deficiencies can greatly reduce yields. Potassium fertilizer rates should be based on soil test results.

Early Planting

Soybeans should not be planted until soil temperature reaches 60 F. Because emergence may also be affected by cool soil temperatures after planting, early planting decisions should also consider the forecast up to seven days after planting. Adequate soil temperatures are often observed in April but can vary by location and year. Maturity Group IV and indeterminate Group V varieties perform best in April plantings. Research in north Louisiana has shown instances of high yields for Group IV and V planted in mid-to-late March. In these cases, daily average soil temperatures were generally at or above 60 F at planting. A few (especially determinate types) may be sensitive to planting before early May. Narrow row spacing may be beneficial when planting early because of the potential of reduced plant height. Always use a base fungicide seed treatment when planting early and conditions are less than favorable.

Late Planting

When planting is delayed until June 15 or later, the amount of vegetative growth that the plant produces becomes more critical. It is important to choose varieties that grow rapidly in a short time. When blooming starts, most vegetative growth ceases in determinate varieties. Maturity Group V soybeans should be used when planting after June 1. When planting late, seeding rates should be increased to compensate for reduced vegetative growth.

Seeding Rate

Plant populations that are too dense reduce yields, encourage diseases and lodging, and increase seed cost. When calibrating planters, use seed-per-foot as your guide rather than pounds of seed per acre. In the following table, the estimated pounds per acre should be used only to calculate how much seed to buy. Because of varietal difference in seed size, as well as seasonal variation within lots of the same variety, planting rates can be misleading if expressed in pounds per acre. The following rates are recommended:

Planting Dates

Because weather conditions are different from year to year, planting dates can be affected by environmental conditions. Early or late planting can cause a reduction in plant height in many varieties. Generally, late plantings have less chance of success unless irrigation is available or optimal weather and timely rains occur throughout the growing season. A general rule is that half a bushel per day is lost for every day that planting is delayed past the first week of June.

Optimal seeding dates for each maturity group planted in Louisiana are:

Row Spacing

Varieties respond differently to row spacing. An important consideration is that the canopy closes as quickly as possible to avoid late-season weed problems and to maximize the amount of light captured. Research has shown that narrow row spacing (30 inches or fewer) may outyield wide row spacing in some environments.

Depth of Seeding

Plant only deep enough to get the seed in moist soil. On sandy or silt loam soils, plant 1 inch deep if moisture is available. On clay soils, plant 1 to 2 inches deep, depending on moisture conditions. Rolling the soil, especially clays, after planting will help obtain a standby conserving moisture.

David Moseley
Assistant Professor
Dean Lee Research Station

Boyd Padgett
Professor
Dean Lee Research Station

Trey Price
Associate Professor
Macon Ridge Research Station

Manoch Kongchum
Associate Professor
H. Rouse Caffey Rice Research Station

Daniel Stephenson
Professor
Dean Lee Research Station

Rasel Parvej
Assistant Professor
Macon Ridge Research Station

James Villegas
Assistant Professor
Dean Lee Research Station

Dawson Kerns
Assistant Professor
Macon Ridge Research Station

Jeff Davis
Professor
Department of Entomology

Tristan Watson
Assistant Professor
Department of Plant Pathology and Crop Physiology

Dennis Burns
Station Director
Northeast Research Station

Christopher Roider
Research Associate
Central Region Station

Greg Williams
Research Associate
Iberia Research Station

Russell Anderson
Research Associate
Red River Research Station

Bill Waltman
Research Associate
Red River Research Station

James Leonards
Research Associate
H. Rouse Caffey Rice Research Station

Jacob Fluitt
Research Associate
H. Rouse Caffey Rice Research Station

Tashia Monaghan
Research Associate
Dean Lee Research Station

Myra Purvis
Research Associate
Macon Ridge Research Station

Dustin Ezell
Research Associate
Macon Ridge Research Station

Brady McKay
Research Associate
Macon Ridge Research Station

Katarzyna Fic
Research Associate
Dean Lee Research Station

Bruce Garner
Parish Agent – West Carroll Parish

Mark Carriere
Parish Agent – Pointe Coupee Parish

Vince Deshotel
Parish Agent – St. Landry Parish

Justin Dufour
Parish Agent – Avoyelles Parish

Carol Pinnell-Alison
Parish Agent – Franklin Parish

Randall Mallette
Parish Agent – Natchitoches Parish