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David Moseley, DeWitt, Noah, Kerns, Dawson, Davis, Jeff A., Price, III, Paul P, Padgett, Guy B., Harrison, Stephen A., Villegas, James M.
David Moseley, Leandro Vieira, Saulo Castro, and Jim Wang, LSU AgCenter Scientists
Nitrogen fixation is a process where soybean plants can utilize nitrogen from the air by a symbiotic relationship with Bradyrhizobium japonicum bacteria and is essential for economical soybean production. An article written by the Science for Success group (A national team of soybean agronomist) published an article on the Soybean Research & Information Network website stating that nitrogen fixation can account for 40 to 70% of the nitrogen requirement for soybean.
The bacteria that is responsible for nitrogen fixation in soybean is Bradyrhizobium japonicum. If a field has never been planted to soybean, it is likely the seed will need to be inoculated. The bacteria can survive many years until the next soybean crop, but the common recommendation is to inoculate seed if soybean has not been planted for 3 to 5 years. However, research has indicated that an increase in yield is possible if seed is inoculated in a regular soybean rotation. Adverse conditions can reduce the activity of the bacteria, including drought or flooded conditions. An important reminder is that the soybean plants require specifically Bradyrhizobium japonicum for nitrogen fixation. Other legume plants benefit from nitrogen fixation but are associated with other rhizobium bacteria. For more information on different plants and specific inoculants, see this Penn State Extension publication. When applying Bradyrhizobium japonicum, it is important to remember the inoculant is a live organism. Attention to proper storage and timing of application can help minimize a decrease in viability of the bacteria.
Molybdenum (Mo) is an important nutrient for nitrogen fixation. In low pH soils (acidic soils) with low Mo availability, adding Mo may be necessary. It is important to remember that a Mo application can harm the inoculant. If an application of Mo is necessary, it is important not to combine it with the inoculant unless the application is immediately before planting.
David O. Moseley, LSU AgCenter Soybean Specialist
Data from soybean trials conducted from 2013 through 2020 in the Northeast, Central, and Southwest regions of Louisiana were used to determine optimum planting windows by region and, when possible, by maturity group (Table 1).
Table 1. Optimum soybean planting windows for Northeast, Central, and Southwest Louisiana.
| Region (MG)1 | 95% Yield Window (Early PD2) | 99% Yield Window (Early PD3) | PD for Predicted Peak Yield4 | 95% Yield Window (Late PD2) | 99% Yield Window (Late PD3) |
| Northeast All MGs | Mar 06 | Mar 24 | Apr 07 | May 09 | Apr 21 |
| Central 3.0-4.4 | Apr 05 | Apr 15 | Apr 22 | May 08 | Apr 29 |
| Central 4.5-4.7 | Mar 21 | Apr 02 | Apr 12 | May 03 | Apr 21 |
| Central 4.8-4.9 | Mar 31 | Apr 11 | Apr 19 | May 08 | Apr 27 |
| Central 5.4-6.0 | Apr 15 | Apr 24 | May 01 | May 16 | May 07 |
| Southwest 3.0-4.4 | May 13 | May 21 | May 27 | Jun 10 | Jun 02 |
| Southwest 4.5-4.7 | May 06 | May 14 | May 19 | Jun 01 | May 25 |
| Southwest 4.8-4.9 | May 03 | May 12 | May 18 | Jun 02 | May 24 |
| Southwest 5.0-5.3 | Apr 26 | May 04 | May 10 | May 24 | May 16 |
| Southwest 5.4-6.0 | Apr 27 | May 05 | May 12 | May 26 | May 18 |
1The Louisiana region where data points were collected and the maturity group (MG).
295% yield window is the planting-date range where predicted yield is ≥95% of peak.
399% yield window is the planting-date range where predicted yield is ≥99% of peak.
4The planting date for the predicted peak yield.
The planting window to achieve at least 95% of yield potential in the Northeast region ranged from March 6 through May 9, with a predicted peak yield occurring on April 7.
Depending on maturity group, the planting window to achieve at least 95% of yield potential in the Central region ranged from March 21 through May 16, with predicted peak yield dates occurring between April 12 and May 1.
Depending on maturity group, the planting window to achieve at least 95% of yield potential in the Southwest region ranged from April 26 through June 10, with predicted peak yield dates occurring between May 10 and May 27.
The amount of yield loss associated with planting earlier or later than the optimum timing depends heavily on environmental conditions during the growing season. April has traditionally been considered the ideal soybean planting window in Louisiana; however, recent years have challenged this assumption.
In both 2022 and 2024, high-yielding soybeans planted in April experienced severe damage due to prolonged rainfall events during the maturation period. These early-planted fields were particularly vulnerable because they reached maturity during peak rainfall, resulting in widespread crop losses. In 2025, soybeans planted in late March and early April flowered prematurely and exhibited reduced plant height, possibly due to persistent cloudy and rainy conditions during early vegetative growth. A susceptible variety planted at the Dean Lee Research and Extension Center during this period developed severe Cercospora leaf blight, resulting in little to no seed production.
Conversely, in 2023, statewide soybean yields were approximately 14% below the 10‑year average, largely due to heat and drought stress during seed fill. In that year, soybeans planted in May were more susceptible to yield loss than those planted in April.
These observations suggest that three of the last four years (2022–2025) featured conditions where May or June planting dates may have reduced risk compared with April planting. Evaluating later planting windows is therefore important not only for risk management but also for assessing opportunities such as double cropping with wheat or canola, which could improve farm profitability if late-planted soybean remains viable.
Implementing staggered planting dates is one strategy to mitigate the risk of severe weather-related damage. Table 1 indicates that planting soybeans within the recommended window in each region yields at least 95% of the optimal potential.
Planting in March does carry an increased risk of freeze damage. Maps from the National Centers for Environmental Information indicate that some areas of north Louisiana can experience their last spring freeze between March 16 and March 30. Producers considering early planting should weigh freeze risk alongside potential yield benefits.
Additional information can be found in the Moseley et al. (2024) article and in a Science for Success factsheet called The Best Soybean Planting Date.
Jeffrey A. Davis, Dawson D. Kerns, and James Villegas, LSU AgCenter Entomologists
Contained in each kit were a set of instructions, 10 control vials, 10 test vials, a data slip, and gloves (Fig. 1). In brief, the objective was to collect a set of stink bugs using a sweep net, place a single adult in each tube, and evaluate if they were alive or dead after 4 hours. Results were marked on the data slip and then a picture of the results were texted to us.
Lessons were learned from last year’s testing. First lesson, populations of redbanded stink bug within the state differ in their susceptibility to acephate (Fig. 2). We completed evaluations and saw a slight increase in tolerance to acephate. This did not indicate acephate failure but caution in using lower rates. The second lesson is that we need to assess early and often from cover crops and soybeans to prepare for later season applications. Thirdly, we need to expand our testing network. We need more samples from throughout the state, ideally in each parish. We need your help. Please consider participating in the program this year in 2026. If you would like a test kit, contact one of us via email or text. Thank you for your consideration.
| Dr. Jeffrey (Jeff) A. Davis Austin C. Thompson Distinguished Professor in Entomology Field Crop Entomologist Department of Entomology LSU AgCenter 404 Life Sciences Building Baton Rouge, LA 70803 (225)-747-0351 | Dr. Dawson D. Kerns Assistant Professor-Field Crop Entomology LSU Ag Center (Northeast Region)-T.H. Scott Research, Extension, and Education Center 212A Macon Ridge Road Winnsboro, LA 71295 (806)-474-7220 | Dr. James Villegas Assistant Professor, IPM Coordinator, & Extension Field Crop Entomologist A. Wilbert's Sons Professorship in Agriculture & Natural Resources Dean Lee Research and Extension Center 225-266-3805 |
Boyd Padgett, Trey Price, Steve Harrison, Noah DeWitt, LSU AgCenter Scientists
Currently, leaf rust has been observed at the Dean Lee (Alexandria), Rouse Caffey Rice Station, Macon Ridge (Winnsboro), Doyle Chambers (Baton Rouge) Research Stations. Information on disease development and symptoms is listed below.
Stripe rust development is most aggressive when temperatures are 50 to 65°F in the presence of intermittent rain or dews (6 to 8 hours). However, development can occur when temperatures range from near freezing to 70°F. Initial infections on seedling wheat may not have the characteristic striping pattern that occurs on older plants. Seedling infections often occur in ‘thumb-sized’ clusters on the leaves, as opposed to a random distribution that occurs with leaf rust. Infections may appear as linear rows of small yellow to light orange pustules (stripes) on the lower leaves during late winter or early spring. Striped patterns are typical of infections in older pants. If conditions remain favorable for development, pustules may cover the entire upper leaf surface, as well as portions of the head. A lifecycle (infection to reproduction) can be completed within 7 to 10 days under optimum conditions.
Stripe rust
Stripe rust in the lower canopy on early season wheat
Stripe rust on tillering wheat
Hot spot of stripe rust
Leaf rust is usually evident later in the season than stripe rust. This is because the leaf rust pathogen requires warmer temperatures for development. Initial symptoms of leaf rust begin as brick red spots, usually on the lower foliage. As the disease develops, small pin-point pustules form on the upper leaf surface. Pustules are dark orange to brick/dark red and occur randomly on the leaf. Similar to stripe rust, pustules can cover the entire leaf surface if conditions remain favorable for development. A lifecycle can be completed 7 to 10 days. The disease develops optimally when nighttime temperatures are 50 to 70°F and leaves remain wet for 6 to 8 hours.
Leaf rust
Leaf rust
Managing stripe and leaf rust is accomplished using resistant varieties. These ratings can be found at: http://www.lsuagcenter.com/topics/crops/wheatoats/variety_trials_recommendations. This information can be used to avoid planting a susceptible variety. This should be the first line of defense; however, if genetic resistance is not available, some fungicides are effective. To manage rust and other foliar diseases, fungicide applications should be made when wheat is at flag leaf emergence (F8). Fungicide recommendations can be found in the Plant Disease Management Guide on the LSU AgCenter website Louisiana Plant Disease Management Guide (lsuagcenter.com).
Sprayers should be configured to optimize coverage. Poor coverage of a good fungicide could result in poor disease control. Coverage is affected by gallons per acre, pressure, nozzle size, nozzle type, and nozzle spacing. Aerial fungicide applications should deliver fungicides in 4 to 5 gallons of total solution per acre and ground applications should be configured to deliver 10 to 20 gallons per acre.
For more information concerning disease management in wheat, contact your local LSU AgCenter County Agent/Specialist or Agricultural Consultant.
Boyd Padgett, Trey Price, Steve Harrison, Noah DeWitt, LSU AgCenter Scientists
Fusarium head blight (scab) can devastate wheat if not properly managed. The fungus damages the grain directly and produces the mycotoxin deoxynivalenol (DON) which is toxic to animals and humans. Damage caused by this disease was in part responsible for the lowest wheat acreage on record for Louisiana in recent years. There are several reasons this occurred. First, warm and wet weather conditions during flowering favored infection. Second, these conditions persisted which fueled epidemics. Third, there are no highly effective management practices, making the disease difficult to manage. However, genetic resistance is improving and new fungicides are more efficacious than older chemistries.
The fungus can infect corn; therefore, wheat grown in fields planted to corn the previous year may be at higher risk to this disease. Infected corn debris (also wheat straw and other hosts) can serve as initial inoculum. Fungal spores produced on this debris are dispersed by rain splash or wind to nearby wheat plants. Other inoculum can be introduced into the field as windblown spores. Later in the season, plant to plant spread is possible. Infection can occur from head emergence to harvest, but infection during flowering through soft dough is most damaging. Conditions that favor infection are temperatures from 75-85oF and 48-72 hours of free moisture.
Symptoms of the disease can appear 10 to 14 days after flowering as bleached heads, which will be evident from the turn row. This symptom is often mistaken with the appearance of maturing wheat. Upon closer inspection, affected wheat heads will usually have infected kernels showing the characteristic bleached appearance with pinkish/salmon/light orange coloration along the glumes. This coloration is millions of microscopic spores (reproductive structures) of the fungal pathogen. There are usually healthy kernels along with the diseased kernels on the same head; however, the entire head may be infected in extreme cases. At harvest, affected seed will be shriveled, off color, much lighter than healthy kernels, and are referred to as “tombstones”.
Bleached heads infected by scab fungus
Salmon colored fungal spores on grain
Infected seed on left and healthy seed on right
While there is no single effective management practice, combining a moderately resistant variety with a timely fungicide application (beginning flowering) for suppression can reduce the damage from this disease. It is important to have a management plan in place before planting. Over the past several years, LSU AgCenter scientists have been able to evaluate scab severity in varieties at some LSU AgCenter official variety trial locations.
These ratings can be found at: http://www.lsuagcenter.com/topics/crops/wheatoats/variety_trials_recommendations. This information can be used to avoid planting a susceptible variety. However, varieties that rate low for scab may not be resistant, because conditions may not have been conducive for infection at the time of flowering. Determination for genetic resistance should be based on multiple locations and years when scab was present. AgCenter scientists also collaborate with other scientists across the U.S. as a part of the U.S. Wheat and Barley Scab Initiative. Efforts from this multi-state initiative are directed toward identifying varieties and practices to manage this disease. In addition, new and existing fungicides are evaluated to manage this disease.
Other management practices that may aid in management include: crop rotation with non-host crops, tillage, mowing/shredding, or staggered planting/varietal maturity. At harvest, combine fan speed may be increased to blow out infected seed, which is lighter than healthy seed. These cultural practices alone will not completely manage FHB. An integrated approach is required to lessen the impact of FHB.
Genetic resistance is not bulletproof. This resistance can break down over time with pathogen populations evolving to overcome resistance. Therefore, agents, producers, and consultants should always scout their crops beginning no later than early spring.
When genetic resistance erodes and disease is identified in resistance varieties, a fungicide application may be needed. Typically, a single application at flag leaf emergence (F8) is adequate for managing most foliar diseases of wheat. Fungicide recommendations can be found in the Plant Disease Management Guide on the LSU AgCenter website Louisiana Plant Disease Management Guide (lsuagcenter.com).
Sprayers should be configured to optimize coverage. Poor coverage of a good fungicide could result in poor disease control. Coverage is affected by gallons per acre, pressure, nozzle size, nozzle type, and nozzle spacing. Aerial fungicide applications should deliver fungicides in 4 to 5 gallons of total solution per acre and ground applications should be configured to deliver 10 to 20 gallons per acre.
Nozzles should be selected that deliver small droplets (200 to 300 microns). Nozzles configured to reduce drift potential will usually result in poor coverage. Boom height and nozzle spacing should be adjusted to the manufacturer’s specifications. A boom height too high will increase the potential for drift and a boom height too low will not provide adequate overlap for the nozzles. Pressure should be adequate to force fungicide down in the canopy.
On a final note, remember that an effective disease management program will only be successful when all of the components are working together. Efforts must be made to correctly identify the diseases. Choose high-yielding, disease-resistant varieties, and make timely applications of an efficacious fungicide when necessary. For more information concerning disease management in wheat, contact your local LSU AgCenter County Agent/Specialist or Agricultural Consultant.
| Specialty | Crop Responsibilities | Name | Phone |
| Soybeans | Agronomic | David Moseley | 318-473-6520 |
| Wheat | Agronomic | Boyd Padgett | 318-614-4354 |
| Pathology | Cotton, grain sorghum, soybeans | Boyd Padgett | 318-614-4354 |
| Pathology | Corn, cotton, grain sorghum, soybeans, wheat | Trey Price | 318-235-9805 |
| Entomology | Corn, cotton, grain sorghum, soybeans, wheat | James Villegas |
225-266-3805 |
| Weed science | Corn, cotton, grain sorghum, soybeans | Stephen Ippolito | 318-473-6520 |
| Nematodes | Agronomic | Tristan Watson | 225-578-1464 |
| Irrigation | Corn, cotton, grain sorghum, soybeans | Stacia Davis Conger | 904-891-1103 |
| Ag economics | Cotton, feed grains, soybeans | Kurt Guidry | 225-578-3282 |
| Soil fertility | Corn, cotton, grain sorghum, soybeans | Leandro Vieira | 225-578-2110 |
| Corn, Cotton, and Grain Sorghum | Agronomic |
Shelly Pate Kerns | 318-435-2908 |
| Entomology | Field Crops | Dawson Kerns | 806-474-7220 |
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Should you need any ADA accommodations, please contact David Moseley at 479-466-0457 no later the 10 days prior to the event.
