Volume 12, Issue 8 - September 2022

David Moseley, Davis, Jeff A., Hendrix, James, Harrison, Stephen A., Price, III, Paul P, Padgett, Guy B., Parvej, Md Rasel, Towles, Tyler, Reis, Andre, Majs, Franta, Foster, Matthew, Miller, Donnie K., Dodla, Syam, Villegas, James M., Wang, Jim Jian, Tubana, Brenda S.

Louisiana Crops Newsletter Plain Banner.jpg thumbnail

Late Season Soybean Damage in Louisiana

David Moseley and Andre Reis, LSU AgCenter Scientist

Article Highlights:

  • Heat and drought caused stress on soybean plants during pod development
  • Excessive rain in August caused sprouting and rotting of seed inside the pod
  • An estimate of 30-50% of the soybean acres have seed damage

It is an understatement to say soybean farmers have had a challenging year in 2022. In April, farmers had to plant around several rain events. Despite the several April showers, 59% of the soybean fields in LA were planted by May 1 compared to the five-year average of 43% and 23% from last year. The timely planting season gave hope for a good crop since previous research suggests higher yield potential when soybean is planted in April. By June unfortunately, the perspective changed. Many regions experienced heat and drought stress as the pods were developing. An article from the University of Maryland Extension explains final pod size can be decreased as of result of heat and drought stress during development. In late August, when growers were preparing for harvest and still uncertain about the yield penalty due to the heat and drought, excessive rain fell across the state until early-September. Data from the Louisiana Agriclimatic Information System shows the Chase Research Station had a total of 20.38 inches of rain from August 1 to September 11. From August 18 to September 8, in the south, central, and north regions of Louisiana, there were 19, 18, and 18 days of measurable rain with a total of 5.1, 12.5, and 17.8 inches of water, respectively.

The excessive rain volume and duration provided enough moisture to cause damage to mature and soon-to-mature seeds. As the seed swelled due to moisture, the ventral suture of many pods split open allowing additional moisture to enter the pod and for the sprout to grow out of the pod (Figures 1 and 2). By the end of the seed filling phase, the concentration of abscisic acid hormone is reduced which allows the seed to germinate if certain thresholds of temperature and hydration are matched. More information on seed sprouting can be found in this article from the University of Missouri. Pod splitting and subsequently seed sprouting were possibly exacerbated due to a smaller pod size caused by the heat and drought stress. In addition to seeds sprouting in the pods, most plants maturing towards the end of August have had seed damage ranging from minimum to more than 60%.

While traveling around Louisiana to assess the damage, it was noted that fields planted in early to mid-April were reaching maturity during the middle of the excessive rain event and presented greater damage. On one farm, soybean was planted on April 2 and April 29. On the day of evaluation, the soybean planted on April 2 had severe damage to mature seed, however the soybean planted on April 29 still had green seed with no apparent injury (Figure 3). It was clear that the level of damage was affected to differences in planting date or maturity group. No tolerant variety was identified. At the time of writing this article, it is still too early to have a completely accurate estimate of the seed damage. However, a statewide survey indicates approximately 30-50% of the acres could have quality damage from the excessive rain.

pic 1pods opening at the ventral suture 2png

Figure 1. As the seed swelled due to moisture, the ventral suture of many pods split open allowing additional moisture to enter the pod and for the sprout to grow out of the pod

Pic 2Sproutsjpg

Figure 2. Soybean seed sprouting out of the pod

Pic 3des not des green with letter editedpng

Figure 3. Soybean seed from three fields (pictures A, B, and C) at a farm in Northeast Louisiana. Fields A and B were planted on April 2 with the same variety. Field A was desiccated before the excessive rain but the field B was not desiccated. The third field (picture C) was planted on April 29.

Pic 4Three stages all togetherjpg

Figure 4. Soybean pods and seed from the core-block in Franklin parish. The demonstration was planted on April 22. The seed damage consisted of sprouts and weathered seed. There were also green seed that showed minimum damage from sprouting or weathering. There was some damage to green seed which may have been a result of stink bug damage. The many days of consecutive rain limited some field work including spraying for insects and disease.

Pic 5whole plant and seed quality with letters editedpng

Figure 5. Many fields with mature soybean looked good after the rain. Unfortunately, the seed was damaged inside the pods.

Lime Quality and Application Rate

Rasel Parvej, Brenda Tubana, Jim Wang, and Syam Dodla, LSU AgCenter Soil Scientists; Jamil Uddin, LSU AgCenter Postdoctoral Researcher; James Hendrix, Conservation Agronomist, Northeast Region; Franta Majs, LSU AgCenter Soil Testing and Plant Analysis Laboratory Director

Article Highlights:

  • Liming materials should have more than 80% CCE (calcium carbonate equivalent) and/or 50% ENV (effective neutralizing value) and the recommended lime rate should be adjusted based on these two qualities.
  • Finer lime particles are more efficient in increasing soil pH by reacting quickly with soils, but liming materials should have both smaller and larger particles so that smaller particles can raise the soil pH quickly and larger particles can have a long-term control in neutralizing soil acidity.

Lime Quality:

  • The quality of liming materials is very important to raise soil pH. There are two qualities of liming materials: purity and particle size. The purity of a liming material is determined in relation to pure calcium carbonate (CaCO3, calcitic limestone), which is rated as 100% (the molecular weight of pure calcium carbonate is 100 g) and this rating is called calcium carbonate equivalent (CCE).
  • Another lime quality is the particle size, also known as fineness factor of liming material and is expressed as the percentage of liming material passes through various sized screens. The higher the percentage of liming material passes through the larger size screen (i.e., smaller hole), the greater the fineness factor would be. Finer particles are more efficient in neutralizing soil acidity (increasing soil pH) by reacting quickly with soils due to greater surface area or soil contact. However, the liming materials should have a good distribution of particle sizes with both smaller and larger particles so that smaller particles can raise the soil pH quickly and larger particles can have a long-term control in neutralizing soil acidity. According to current Louisiana recommendations for ground lime, 90% of liming materials should pass through a 10-mesh sieve, 50% should pass through a 60-mesh sieve, and 20% should pass through a 100-mesh sieve.
  • Both purity (CCE) and particle size (fineness factor) of the liming material are expressed together as effective CCE (ECCE) or effective neutralizing value (ENV). The higher the ECCE or ENV of the liming material the more efficient it is in increasing soil pH.

Lime Application Rate:

The rate of lime recommended by soil testing labs is based on pure calcitic limestone with 100% CCE. So, the actual lime application rate should be adjusted based on the CCE of the liming materials. For example, if the CCE of the liming material is 80% and the recommendation is 2-ton lime per acre, 2.5-ton lime (2-ton/0.80) per acre should be applied. Also, the actual lime rate needs to be adjusted with the ENV of the liming material if the recommendations are based on ENV. For example, if the ENV of the liming material is 60%, but the recommended lime rate is based on standard calcium carbonate with 90% ENV, 1.5-ton (0.9/0.6) lime per acre should be applied for every 1-ton of lime recommended. Note that the lime recommendations from LSU AgCenter Soil Testing and Plant Analysis Lab is based on 50% ECCE or ENV.

Liming Consideration and Application Time

Rasel Parvej, Brenda Tubana, Jim Wang, and Syam Dodla, LSU AgCenter Soil Scientists; Jamil Uddin, LSU AgCenter Postdoctoral Researcher; James Hendrix, Conservation Agronomist, Northeast Region; Franta Majs, LSU AgCenter Soil Testing and Plant Analysis Laboratory Director

Article Highlights:

  • Liming depends on target soil pH that varies with crop, and lime is required if the target soil pH is 0.2 unit more than the actual soil pH.
  • Lime should be applied followed by incorporation in the Fall since it takes long time to raise soil pH.

After receiving soil test report, the first thing that needs to be checked is soil pH. Soil pH is the most important soil quality component that greatly influences soil nutrient availability. Most nutrients are highly available at the soil pH of 6.5 (Figure 1). Therefore, soil pH needs to be adjusted to the target pH either by applying lime for low pH (<6.0) soils or by elemental sulfur for high pH (>7.5) soils. Increasing soil pH by liming is a more common practice than decreasing soil pH by elemental sulfur. The following things need to be considered before making liming decision.

Liming Consideration:

  • The rate of lime depends on the initial and target soil pH values as well as the buffering capacity of the soils (i.e., buffer pH, the ability of a soil to resist the change of pH). Lime rate would be low for soils with low buffering capacity (high buffer pH) and small difference between initial and target soil pH values. However, for soils with high buffering capacity (low buffer pH), lime rate would be high even for a small change of soil pH. Clay (fine-textured) soils have higher buffering capacity and require greater amount of lime for each unit increase of soil pH than silt loam (coarse-textured) soils. Note that LSU AgCenter Soil Testing and Plant Analysis Lab does not determine lime requirement based on buffer pH but indicate the unit change of soil pH with the addition of maximum 3 tons of lime per acre assuming higher than 3 tons lime per acre may be too expensive and let the producers decide how much to apply based on their cost benefit analysis.
  • The target soil pH should be determined based on the crop to be grown. For example, soybean is more sensitive to low soil pH than corn and cotton. The target soil pH should be set at 6.3 for soybean and 6.0 for corn and cotton. Lime is required if the target soil pH is 0.2 unit more than the actual soil pH.

Application Time:

  • Lime usually takes long time, at least 6-9 months, to react with the soils and raise soil pH. However, lime reaction time with soils depends on the quality of liming materials, lime incorporation, soil temperature, and rainfall amount and distribution pattern. Therefore, lime should be applied uniformly and incorporated by tillage for till fields in the Fall.
  • For no-till fields, increasing soil pH by liming within a short period of time is difficult due to lack of incorporation. Therefore, soil pH needs to be monitored more often in no-till fields, if possible, each year. Also, special attentions are required for fields with low buffering capacity that receive high rates of ammonium (NH4+) based fertilizers (urea, UAN, or ammonium sulfate) because ammonium fertilizer decreases soil pH. Producers should not let the soil pH go down too far from the target level for these types of fields.

Rasel Picture1png

Figure 1. Soil pH and nutrient availability [Source: Reitsma et al. (2011). Chapter 2: Soil fertility. In: Alternative practices for agronomic nutrient and pest management in South Dakota. Edition: I. South Dakota State University, College of Agriculture and Biological Sciences]

Managing Juvenile Growth and Terminal Regrowth in Cotton

Matt Foster and Donnie Miller, LSU AgCenter Scientists

Article Highlights:

  • Environmental conditions have resulted in tremendous juvenile growth prior to defoliation as well as terminal regrowth potential following defoliation in the 2022 cotton crop.
  • When selecting harvest aids, activity on juvenile growth and terminal regrowth prevention should be important considerations.

With excessive rainfall recently received in most cotton producing areas of the state, juvenile growth prior to defoliation as well as terminal regrowth following defoliation is a common issue impacting defoliation decisions. Activity on juvenile growth and terminal regrowth prevention should be included in determining factors in product selection.

Terminal regrowth vegetation is difficult to defoliate because the tissue does not form abscission layers. Basal regrowth is often the first to form and hardest to control, but generally doesn’t cause issues at harvest. New leaves that emerge after defoliation can appear as terminal regrowth and contribute to green staining, fine leaf trash, and excessive moisture in seed cotton. Excessive regrowth vegetation must be removed before harvest, requiring the use of certain harvest aid products.

Factors other than excessive moisture that promote terminal regrowth include:

  • Warm temperatures. Favorable temperatures can lead to increased regrowth.
  • Light penetration. Once the crop is defoliated, sunlight can easily reach the axillary buds at the base of each branch.
  • Fertility. If soil nitrogen is not depleted by the time of harvest aid application and moisture is available, plants will continue to produce healthy, vigorous growth.
  • Ethephon. High rates of ethephon in your defoliation application may cause increased regrowth.
  • Low yield potential. When maturing bolls are not present to act as carbohydrate sinks, undesirable regrowth may increase.
  • Reduced rates of thidiazuron. Lowering the rate or omitting thidiazuron from your initial harvest aid application can reduce regrowth inhibition, especially with favorable environmental conditions.Rainfall within 24 hr of product application can also reduce activity.
  • Varieties. In the past decade, varieties have become more robust and later maturing.

In summary, harvest aid products Aim, Display, ET, Reviton, and Sharpen, in addition to thidiazuron products, are very effective in removing juvenile vegetation with the initial defoliation application and terminal regrowth with follow up applications. These products, in addition to Def or Folex, are also effective in removing mature leaves. Only thidiazuron, however, provides effective terminal regrowth inhibition once applied. For more information regarding individual product rates, please see the 2022 Mid-South Cotton Defoliation Guide.

Redbanded Stinkbugs Can Cause Damage Until Soybean Maturity

James Villegas, Jeff Davis, and Tyler Towles, LSU AgCenter Entomologists

Article Highlights:

  • Protect soybeans from redbanded stinkbugs until at least R7
  • Consider the pre-harvest interval (PHI) and the maximum active ingredient allowed per growing season when putting out your final insecticide application
  • Unharvested soybean is a potential site for redbanded stinkbugs to survive

Villages pic 1jpg

Close-up picture of redbanded stinkbug. The underside photo shows the characteristic spine protruding between its hind legs and the piercing/sucking mouthparts.

The standard recommendation for control of southern green, green, and brown stinkbugs is to terminate insecticide applications once soybean plants reached the R6.5 growth stage (R6 plus 7-10 days). Feeding by these stinkbug species after R6 typically does not reduce yields. However, soybeans must be protected from redbanded stinkbugs until at least R7 because this pest continues to feed on beans that have dried down. Since redbanded stinkbugs pierce deeper into pods, feeding injury after R6 can cause reductions in weights and quality that may lead to elevator dockage. In fact, previous studies have documented an average seed weight reduction of 10% if redbanded stinkbugs are not controlled past R6.5. The two most important factors to consider when putting out your final treatments, particularly when tank-mixing pyrethroids with acephate or neonicotinoid, are the pre-harvest interval (PHI) and the maximum active ingredient (a.i.) per acre allowed per growing season. See more details in the table below. In addition, soybean that won’t be harvested this year due to poor seed quality/sprouting will be a potential site for redbanded stinkbugs to survive. Destroying habitat will reduce overwintering sites, thereby reducing stinkbug populations that might survive the winter.

Recommended insecticides for redbanded stinkbugs.

Insecticide

Active Ingredient

PHI (days)

Restrictions

Orthene

acephate

14

maximum of 2 lb a.i. per acre per crop cycle

Endigo ZC

thiamethoxam + lambda-cyhalothrin

30

not to exceed 9 fl oz of Endigo ZC or 0.06 lb a.i. of lambda-cyhalothrin-containing products or 0.125 lb a.i. of foliar-applied thiamethoxam-containing products per acre per growing season

Brigade

bifenthrin

18

not to exceed 19.2 fl oz per acre of Brigade or 0.3 lb a.i. per acre per crop season

Hero

bifenthrin + zeta-cypermethrin

21

not to exceed 41.2 fl oz per acre of Hero or 0.4 lb a.i. per acre per crop season

Leverage 360

imidacloprid + beta-cyfluthrin

21

not to exceed 9 fl oz per acre of Leverage 360 (0.07 lb ai of beta-cyfluthrin per acre and 0.14 lb a.i. of imidacloprid per acre) per crop season

Belay

clothianidin

21

Scheduling Soil Fertility Tests Can Vary with Cropping Systems

James Hendrix, Conservation Agronomist, Northeast Region

Rasel Parvej, LSU AgCenter Soil Fertility Specialist and Jamil Uddin, LSU AgCenter Postdoctoral Researcher

Article Highlights:

  • Fall vs spring soil testing can result in varied results
  • Crop residue can affect soil test results
  • Winter/summer cover crops must be managed for optimum nutrient benefits

Balancing soil nutrients to optimize production and profit is a basic management practice that should begin with a soil test. Soil fertility testing can identify nutrient deficiencies and surpluses and nutrient availability for the crop to be grown and potential environmental concerns. Excessive nutrients in the soil can lead to environmental pollution.

Fall soil testing is common in Louisiana, especially if you expect issues with pH that need addressing prior to planting spring and summer crops. If lime is recommended, it should be applied several months in advance of planting summer crops to reduce soil acidity.

If soil fertility recommendations are the major focus for soil testing, fall vs early spring soil testing can provide mixed results. After harvesting crops, substantial amounts of nutrients remain in the remaining crop residue left in the field. High residue crops such as corn and rice contain more K than P in the biomass. Corn residue from a 200-bushel crop can contain approximately 30 lb. P2O5 and 200 lbs. K2O per acre. Rice residue at the same yield can contain around 15 lbs. P2O5 and 100 lbs. K2O per acre. Since K is not a part of the plant’s cell wall or other molecular structure, it can be leached from residues by rain events following harvest. This can result in higher soil-test K levels in December-January versus results from sampling in September-October. Research in Arkansas has shown that soil-test P and K concentrations change from September to March and the change was affected by the former crop grown. Soil testing for high residue crops such as rice and corn that was completed in December-January revealed higher nutrient values, reducing fertilizer recommendations.

Soil fertility tests completed in the fall should consider the additional nutrients provided by the previous crop residue, as well as produced or scavenged by winter cover crops planted in the fall. Timing cover crop termination to maximize the objective(s) for planting while minimizing any negative impact to the crop following must be considered. Residue from cover crops with a low C:N ratio, such as legumes, breaks down and releases nutrients quickly after termination but may leave the soil vulnerable to erosion. Cereal cover crops can take several weeks to break down, releasing nutrients slower over time, but reduce the issue of erosion. Nutrient release and plant availability from the crop residue can be affected by many factors such as the weather, soil properties, tillage, etc. Utilizing a suite of best management practices (BMPs) such as residue management, cover crop management, reduced tillage, etc. can boost nutrient availability for crops and minimize losses from erosion. Research trials are currently being conducted at the Louisiana State University AgCenter – Macon Ridge and Northeast Research Stations to identify the optimal time to soil sample after corn, cotton, rice, and soybean harvests.

Soil Sampling, Testing, and Fertilizer Recommendations

Rasel Parvej, Brenda Tubana, Jim Wang, and Syam Dodla, LSU AgCenter Soil Scientists; Jamil Uddin, LSU AgCenter Postdoctoral Researcher; James Hendrix, Conservation Agronomist, Northeast Region; Franta Majs, LSU AgCenter Soil Testing and Plant Analysis Laboratory Director

Article Highlights:

  • Soils from each field should be tested on a regular basis before making any fertilization decision.
  • Soil-test-based fertilizer recommendations for a particular crop should be obtained from the state soil testing lab since the recommendations vary with crop and state.
  • Soil testing is only reliable for phosphorus (P), potassium (K), sulfur (S), zinc (Zn) and lime recommendations.

Soil sampling for liming and fertilizer recommendations is a very common practice after summer crop harvest in the Fall. The following things need to be considered before soil sampling, testing, and fertilizer recommendations.

Soil Sampling:

  • Soil should be tested at least once in every 2-4 years or once in a complete crop rotation.
  • Soil sample should be taken at the same time of each sampling year and at a constant depth of 0-6 inch with a soil probe or auger.
  • At least one composite sample should be taken for every 10 acres of land for zone sampling and 2.5 acres of land for grid sampling. The area associated with both zone and grid samplings depend on spatial variability of the field. More soil samples are needed per unit area for highly variable fields. Therefore, soil type and color, topography, past management, and yield map should be considered to determine the actual zone and grid sizes.
  • Each composite soil sample should consist of 12-15 subsamples (i.e., 1-2 subsamples per acre for zone sampling and 5-6 subsamples per acre for grid sampling). However, more subsamples are needed for fields that received fertilizer banding and/or manure spreading in the past. Subsamples should be taken in a zigzag pattern within each zone or grid.
  • During sampling, the thin layer of soil surface should be scraped to remove any vegetation before inserting the soil probe or auger. For furrow irrigation system, each sample should be taken from the top of the bed (4-6 inch apart from crop row). However, for any field, soil sample should not be taken from fertilizer bands, manure or lime stockpiles, wet spots, fence rows, and from an area that is too small to be managed separately. All subsamples should be mixed thoroughly in a clean plastic bucket and stones, roots, stems, trash, and other debris should be removed from the mixed soil samples.
  • Each composite soil sample should be placed separate in a clean plastic or paper bag with clear labelling that includes farm name and location, sampling date and depth, previous crop, and expected crop to be grown and sent immediately to the soil testing lab for routine soil analysis.

Soil Testing:

  • Soil samples should be tested in a certified soil lab (e.g., LSU AgCenter Soil Testing and Plant Analysis Lab, Baton Rouge) that uses the same soil extraction methods that were used to develop fertilizer recommendations for that state. Soil-test-based fertilizer recommendations in Louisiana are based on Mehlich-3 soil exaction method for soil sample collected from 0-6-inch depth.
  • Soil samples should be analyzed in the same lab each year to create a historic record.

Soil Test Results Interpretation and Fertilizer Recommendations:

  • Soil test results should be interpreted based on recommendations developed from correlation and calibration research conducted across multiple site-years. Since soil-test-based fertilizer recommendations vary with crops and states, soil test results for a particular crop of a particular state should be interpreted with that crop specific recommendations developed by that state. Usually, soil scientists from every land-grant university develop their own recommendations for each crop. So, it is preferred to analyze soil sample in the state soil testing lab and obtain fertilizer recommendations from that state lab. Note that fertilizer recommendations obtained from different states lab (public or private) may not be accurate and may often time higher than the actual need.
  • Soil testing is only reliable for phosphorus (P), potassium (K), sulfur (S), zinc (Zn), and liming recommendations. Therefore, soil-test-based recommendations for other nutrients from any soil test labs may not be accurate. Fertilizer recommendations for most micronutrients [Boron (B), Iron (Fe), Manganese (Mn), and Molybdenum (Mo)] depend on soil pH. In general, micronutrients except Mo is recommended for fields with pH higher than 7.5 and Mo is recommended specifically for soybean production in fields with pH less than 6.0 and no lime was applied in the previous Fall.

Wheat Production Practices in Louisiana

Boyd Padgett, Stephen Harrison, and Trey Price LSU AgCenter Scientist

Article Highlight:

  • Crop management (planting date, seeding rates, fertilization strategies)

Crop management:

Planting dates depend on location and variety. Southern and central Louisiana range from November 1-30. For northern Louisiana (slightly earlier) ranging from October 15 to November 15. Early-heading varieties should generally be planted after the mid-date, while late-heading varieties can be a little on the early side of the planting window. It is important the wheat crop be well-established and fully tillered before the coldest part of the winter. If wheat cannot be planted within these optimum windows, planting later is usually better than planting early. Planting too late (more than 14 days after the optimum window) can result in significant yield loss due to slow emergence and poor stands.

Wheat is planted by broadcasting seed (90-120 lb/A) incorporation into the soil or drilled (preferred) (60-90 lb/A). Drilling the seed increases the uniformity of depth and uniform emergence. Good surface drainage is critical to successful wheat production.

Total nitrogen should range from 90 to 120 pounds per acre, but will vary depending on soil type and rainfall after applications. The crop needs adequate N in the fall and early winter to establish ground cover and properly tiller, but excessive levels of fall N can result in rank growth, increased lodging, and a higher probability of spring freeze damage from early heading. If wheat is following soybeans, soil residual or mineralized N should be adequate for fall growth, and no pre-plant N is needed. However, if the crop follows corn, sorghum, rice or cotton, the application of 15 to 20 pounds of N per acre would typically be beneficial. Where the wheat crop is planted later than optimum, additional N may be necessary to ensure adequate fall growth prior to winter conditions. If the wheat crop did not receive a fall application and appears to be suffering from N deficiency in January, the initial top dress N application can be made early to promote additional tillering. Early spring is when the majority of N for the wheat crop should be applied. There is no universal rule on how early spring N should be applied. Each field should be evaluated based on tillering, stage of development, environmental conditions and crop color. A crop that has good growth and good color should not need N fertilization prior to erect leaf sheath (Feekes 5), usually sometime in February. However, first spring fertilizer application should be applied prior to first node (Feekes 6) in order to ensure optimum head development, tiller retention and head size. Crop N stress around jointing (Feekes 6) will result in yield losses. Additional N applied following flag leaf typically contributes very little to crop yield. Splitting topdress N into two or three applications is common in Louisiana production systems due to the increased risk of N losses often associated with heavy rainfall and our long growing season. Splitting N typically occurs by applying fertilizer N at or just prior to jointing with a second application occurring 14 to 28 days later. About 50 percent of the topdress N is normally applied with the first split, but this may be decreased if the first split is put out early and plants are not well enough developed to take up that much N.

For further questions or comments contact:

Steve Harrison, Small Grain Breeder, sharrison@agcenter.lsu.edu

Boyd Padgett, Wheat Extension Specialist/Plant Pathologist, bpadgett@agcenter.lsu.edu

Trey Price, Extension Research Plant Pathologist, pprice@agcenter.lsu.edu

Wheat Variety Performance in Louisiana

Stephen Harrison, Boyd Padgett and Trey Price LSU AgCenter

Article Highlight:

  • Variety selection considerations (vernalization/heading date, disease resistance, yield, test weight)

To access the complete 2022 Variety Performance Trial publication, go to the following website: 2022 Variety Performance Trial Publication.

Variety selection:

Choice of varieties for planting is a crucial management decision that sets the stage for yield potential and input costs. While grain yield is the most important factor, test weight, disease resistance, and heading date are important considerations as they also impact economic return.

Test weight is important because low test weight results in dockage at the elevator. Heading day is a function of cold requirement (vernalization) and day length (photoperiod) response that determines when a variety heads out. Some varieties head very late or not at all in south Louisiana due to a long vernalization requirement or photoperiod response, while those same varieties may perform better in north Louisiana or Arkansas. Varieties that fully vernalize but head out late due to long photoperiod requirement perform poorly in south Louisiana due to grain fill during hot weather. By contrast, early heading varieties may yield poorly in north Louisiana due to late spring freeze damage. Vernalization and photoperiod response are the primary reasons for dividing Louisiana into North and South regions.

Early-heading and maturing varieties permit earlier harvest and more timely planting in a double-crop system, while later-heading varieties guard against damage from a late spring freeze and can be planted earlier in north Louisiana. Early-heading varieties should be planted in the second half of the recommended planting window to reduce the likelihood of spring freeze damage. Lodging resistance helps guard against reduction in test weight and yield loss that results when near-mature heads come in contact with the ground.

Disease resistance protects yield and reduces input costs. Disease susceptibility is very important in terms of yield and profitability. Reactions for naturally-occurring diseases are also listed for each variety in Variety Performance Trial publications. There are no varieties fully resistant to FHB, but some have high to moderately high to moderate levels of resistance. It should be noted that varieties less susceptible to disease may not always be the highest yielding, especially if disease pressure is not present. However, in high disease pressure situations, these varieties produce higher yields than susceptible varieties and enhance profitability by saving the costs of fungicide applications.

For further questions or comments contact:

Steve Harrison, Small Grain Breeder, sharrison@agcenter.lsu.edu

Boyd Padgett, Wheat Extension Specialist/Plant Pathologist, bpadgett@agcenter.lsu.edu

Trey Price, Extension Research Plant Pathologist, pprice@agcenter.lsu.edu

9/18/2022 2:54:27 AM
Rate This Article:

Have a question or comment about the information on this page?

Innovate . Educate . Improve Lives

The LSU AgCenter and the LSU College of Agriculture

Top