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d Moseley, LSU AgCenter Soybean Specialist
The USDA-NASS survey reported that two percent of the Louisiana soybean crop was planted by March 19, 2023. The warm and dry weather during early March allowed producers to plant their corn crop early and then begin planting soybeans. Unfortunately, on March 20th, the temperature dropped to approximately 28 degrees Fahrenheit in Northeast Louisiana. Soybean tissue death can occur if the temperature falls to 28 degrees Fahrenheit for more than four hours, especially if the unifoliate leaves are exposed (Vann and Stokes, 2020).
On March 21st and over the following few weeks, the condition of three fields was documented. Two fields were at the LSU AgCenter Northeast Research Station and the other field was near Clayton, LA. The planting dates were March 1, 15, and 6, respectively. For the March 1st and 6th planting dates, with only 30 miles between the two fields, almost 100 percent of the soybean plants at the Northeast research station were killed, but approximately 50 percent of the soybean plants at the field near Clayton, LA survived. One explanation could be that the plants near Clayton, LA were less developed as they were planted five days later. At least 50 percent of the unifoliate leaves were likely still insulated by the cotyledons. The soybean in the field planted on March 15th at the Northeast Research Station was not emerged on March 20th and survived the freeze.
The producer near Clayton, LA planted 160,000 seeds per acre. With an approximate 50 percent survival rate, the final stand was approximately 80,000 plants per acre. According to data from the LSU AgCenter Dean Lee Research Station in 2020, a final stand of approximately 61,000 plants per acre may result in similar yield as a stand of over 100,000 plants per acre. Most University soybean agronomist would agree that 70,000 – 75,000 plants per acre that are healthy and uniformly distributed will allow approximately 95 percent of the full yield potential as compared to a more full stand.
Figure 1. Soybean seedling damage on March 21, 2023. The seeds were planted on March 6th and were in the VE growth stage (the cotyledons had emerged past the soil surface, but the unifoliate leaves had not completely unrolled and in some cases the growing point was still protected by the cotyledons) when the freeze hit Louisiana on March 20th. The cotyledons had suffered damage from the freeze, and it was unknown if the growing point had been killed.
Figure 2. On March 27, 2023, the original main stem on some plants had ceased from growing after the apical meristem was killed during the freeze. However, after the apical meristem was killed, two axillary branches had begun to develop trifoliolate leaves from the cotyledon node.
Figure 3. By April 5, 2023, both axillary branches had developed two open trifoliolate leaves and had another trifoliolate leaf beginning to open on each branch. Both axillary branches can fully develop and replace the original main stem.
Figure 4. It was observed on April 5, 2023, that the apical meristem was not damaged on most plants. The soybean plants were progressing normally and had reached the V2 growth stage (two open trifoliolate leaves). The plants had reached the V2 growth stage approximately 30 days after planting which is within the normal average duration between planting and V2.
Figure 5. The soybean seed was planted on a 7.5 inch spacing with a seeding rate of 160,000 plants per acre. After the March 20, 2023, freeze, the final stand count on April 5 was estimated to be 80,000 plants per acre which can still support close to full yield potential of a field with a full stand.
Reference:
Vann, R., D. Stokes. 2020. Soybean Cold Damage. North Carolina State Extension.
Trey Price and Boyd Padgett, LSU AgCenter Pathologists
Symptoms for Paraquat drift and Holcus spot are similar and are difficult to distinguish from each other. Symptoms appear as round to oval, light tan to white spots with or without yellow halos. Generally, if a drift pattern (gradient) is observed, if affected areas are large and more jagged than round, or if secondary fungi are within lesions, it is likely paraquat drift (Figure 1).If the distribution is random, the spots appear within 48 hours of a thunderstorm, and water-soaking is observed, it is likely holcus spot (Figure 2).Microscopic observation of holcus spot may reveal bacterial streaming, as the disease is caused by Pseudomonas syringae pv. syringae. Both issues are usually of minor concern.
Common rust may be the first disease found in corn fields and usually occurs in the lower-to-mid-canopy. Pustules of common rust are brick red to dark orange, somewhat elongated, and will appear on both leaf surfaces (Figure 3). Common rust will progress during relatively cool, rainy, and cloudy weather; however, very rarely are fungicide applications warranted for common rust. Warmer temperatures will greatly slow common rust development.
Southern rust pustules are more orange than brick red, usually not as elongated, and usually appear on the upper surface of leaves (Figure 4). This disease develops in warmer temperatures than for common rust and can continue to develop throughout the growing season. Like common rust, the disease usually initiates in the lower-to-mid-canopy. The disease can reach the upper canopy during conditions favorable for development. Fungicides may be justified but should be made on a field-by-field basis. The genetic resistance of the hybrid and growth stage (post tassel) and current environmental conditions are factors to consider prior to applying a fungicide.
Northern corn leaf blight (NCLB) is a disease usually seen every year in susceptible hybrids (Figure 5). This disease will first appear in susceptible hybrids in fields following corn with reduced tillage. The disease will progress slowly during dry weather, and more quickly during regular rainy periods. Most of the time fungicide applications are not needed for NCLB. However, severe disease may occur in susceptible hybrids following corn in reduced tillage situations. These are the fields that need to be watched closely.
Fungicide application decisions should be carefully considered field by field based on: disease severity (Figure 6), crop stage (Table 1), hybrid susceptibility, fungicide efficacy, tillage regime, prevailing environmental conditions, previous experience, commodity price, and the probability of a return on the investment. If applications are warranted, apply at labeled rates using maximum (5 GPA by air, minimum) water volume is recommended.
Table 1. Percent yield loss (in blue) because of defoliation by crop stage. The percentage of defoliation is shown on the top row of the table. For example…30% defoliation at dent stage results in a 2% yield loss.
Figure 1. Paraquat drift on corn.
Figure 2. Holcus spot of corn.
Figure 3. Common rust.
Figure 4. Southern rust.
Figure 5. Northern corn leaf blight.
Figure 6. NCLB disease severity scale.
ames Villegas, LSU AgCenter Entomologist
Stink bugs are typically found infesting wheat in Louisiana at this time of the year. While it’s not uncommon to find stink bugs on heading wheat, they rarely cause economic damage. The predominant stink bug species found in Louisiana wheat is the rice stink bug (Oebalus pugnax), although brown stink bugs can also be present. These pests are mostly found around the border edges of the field. It takes high numbers of stink bugs to damage wheat. Treatment is only recommended if the threshold of 1 stink bug per 10 heads during the milk stage and 3 stink bugs per 10 heads during the soft dough stage is reached. Pyrethroids such as z-cypermethrin and lambda-cyhalothrin should be effective against these pests. Once wheat reaches the hard dough stage, damage due to stink bugs is greatly reduced. It’s important to note that stink bugs in wheat are not typically treated, but they can be an indication of stink bug infestations in corn. During harvest, stink bugs can potentially be pushed to nearby corn, so it’s important to scout adjacent corn fields.
The brown stinkbug (Euschistus spp.) is the most common species to attack corn, but the green stink bug (Chinavia halaris) and southern green stink bug (Nezara viridula) can also be a pest. Treatment is recommended if 5% of plants have bugs prior to ear shoot appearance (1 stink bug per 20 plants). For early vegetative stages (V1–V6), treatment is necessary if 10% of plants are infested (1 stink bug per 10 plants). Table 1 provides recommended insecticides for managing stink bugs in corn. Managing stink bugs in corn is critical, as they can cause significant damage resulting in reduced yields and kernel quality.
Rice stink bug (Oebalus pugnax) in wheat. Photo by: J. Villegas
Table 1. Recommended Insecticides for Stink Bugs in Corn
ark Carriere, County Agent, LSU AgCenter
As our evening temperatures begin to warm, you may begin to see swarms of Formosan subterranean termites begin to swarm. These termites come out of their colonies at dusk, often near lights, searching for wood and moisture to form new colonies. Each year these termites swarm from May to June, with their most activity typically seen around Mother’s Day. This year we are just starting to see our first signs of swarms begin.
These termites are not new to Louisiana as they are an invasive species that came to the continental United States from Asia shortly after World War II via wood on cargo ships. Louisiana was one of the first places in the U.S. where these termites established colonies. This is due to the heat and humidity that we have here in Louisiana.
hoto 1. Formosan subterranean termite workers and soldiers are rarely seen. Swarmers will be flying from late April to June.
Formosan subterranean termite colonies grow slowly at first but will eventually become huge and can survive for decades. This is due to the queen becoming very large and laying thousands or tens of thousands of eggs per day. Formosan termites are the most destructive termites in the world due to their large colonies and very aggressive soldiers that are tolerant to high temperatures and feed on a diverse range of wood types. It is estimated that these pests cause $1 billion in damage in the United States annually, with half of that - $500 million – in Louisiana, especially in the southeastern portion of the state towards the New Orleans area.
If you see these termites swarming around your home, it indicates that there may be a nearby colony. We recommend being proactive and search your property for any sources of food or water where a colony may exist such as wood stored on the ground or mulch contacting the foundation of your home, decaying portions of a tree, or any outdoor faucets that may be leaking. In some cases, the infestation may be on your neighbor’s property. So, work with your neighbor and try to locate the source of your infestation. If you cannot locate the source or have a concern, we recommend contacting a local pest control professional.
Photo 2. Termite swarms around light posts and outdoor lightning typically peaks around Mother’s Day.
To reduce the swarmers from being attracted to your home, remove all food and water sources. In the evenings, termites are attracted to a light source. We recommend during peak swarming months to turn off all outdoor lighting, and close blinds or curtains to reduce them swarming around your home. If you do see a few termites in your home during this time, but do not see mud tunnels, there is not much to worry about. Just because you see these swarmers in your home, it does not mean that you immediately have a termite problem. These swarmers will fly in the home and once they land on a surface their wings pop off leaving behind a trail of wings in the home. In most cases if you have them in the home, you can just vacuum them up and dispose of them outside.
If you do see tunnels or a large number of swarmers in the evenings, we recommend contacting a pest control professional to treat your home. As the summertime heat approaches you will begin to see fewer of these termites swarming around your home. For more information about this or other topics please contact Mark Carriere, County Agent, at mcarriere@agcenter.lsu.edu or by calling the Pointe Coupee Extension Office at (225) 638-5533. More information on this and other topics can be found on the web at www.lsuagcenter.com.
Michael Deliberto, LSU AgCenter Economist
The economic impact on farm-level production costs from replanting soybeans and/or corn can result in an increase in the number of additional bushels that will be required to offset the incurred production expenses associated with replanting field operations. The severity of this will depend on the type of seed technology employed, as differences in the prices for seed, seed treatments, and seeding rate which can influence the replanting costs and, hence, the number of additional bushels required at harvest to offset those costs.
In any ‘normal’ crop year, replanting costs play a substantial role in estimating the additional production cost per unit (bushel). However, inflationary pressures and input price volatility observed have cut into expected profit margins and may affect how growers alter their marketing strategy when using the breakeven (BE) cost per unit coupled with a percentage margin when identifying selling opportunities in the futures market. A positive aspect on this situation is that soybean and corn market prices are far better than in recent years, triggered by tight domestic stocks, renewable fuel demand, and increased U.S. export demand. However, substantial increases in production costs have eroded what otherwise would have been healthy profit margins. The following economic analysis employs a general farm management approach to calculate the BE yield required to cover the increase in replanting costs across alternative soybean and corn price levels.
Under the assumption that the farm’s soybean yield is expected to be 55 bushels per acre, estimated total variable production costs for soybeans under irrigation are $495.16 per acre. The BE yield under these imposed conditions is calculated to be 39.61 bushels per acre, assuming a $12.50 per bushel price. The BE price is calculated to be $9.00 per bushel. This can be interpreted to the extent that a producer would need to receive a market price of more than $9.00 per bushel to cover the total variable production costs per acre.
Planting costs (e.g., machinery, fuel, and labor) are comprised of a planter, tractor, and seed. Planter costs are estimated to be $5.30 per acre in addition to the $58.00 soybean seed cost to total $63.30 per acre. If a producer determines that a field must be replanted, the total variable costs for the growing season will increase from $495.16 to $558.46 per acre, reflecting the replanting costs. The new BE yield under these imposed conditions is calculated to be 44.68 bushels per acre, assuming a $12.50 per bushel price. Normal production conditions are assumed. This is an increase of approximately 5 bushels per acre to offset the increase in production costs while the $12.50 price is held constant. The BE price is calculated to be $10.15 per bushel, an increase of $1.15 per bushel.
When the market price is varied from $15.00 to $11.00 per bushel (viewed left-to-right on the horizontal axis) at a yield of 55 bushels per acre, it is observed from Figure 1 that as price declines, more production is required to cover the increase cost of replanting.
Figure 1. Breakeven (BE) yield comparison across multiple price levels for replanting soybeans.
Figure 2 illustrates the required increase (change) in BE yields from replanting a 55 bushel per acre potential field across multiple price levels. As the soybean market price declines, the required increase in BE yield increases from 4.22 (at a $15.00 price) to 5.75 bushels per acre (at a $11.00 price).
Figure 2. Required increase in BE yields from replanting costs in soybeans.
In a similar approach, assuming that the farm’s corn yield is expected to be 190 bushels per acre, estimated total variable production costs for corn under irrigation are $701.96 per acre. The BE yield under these imposed conditions is calculated to be 116.99 bushels per acre, assuming a $6.00 per bushel price. The BE price is calculated to be $3.69 per bushel. This can be interpreted to the extent that a producer would need to receive a market price of more than $3.69 per bushel to cover the total variable production costs per acre.
Planting costs (e.g., machinery, fuel, and labor) are comprised of a planter, tractor, and seed. Planter costs are estimated to be $5.30 per acre in addition to the $118.30 corn seed cost to total $123.60 per acre. If a producer determines that a field must be replanted, the total variable costs for the growing season will increase from $701.96 to $825.56 per acre, reflective of the replanting costs. The new BE yield under these imposed conditions is calculated to be 137.59 bushels per acre, assuming a $6.00 per bushel price. Normal production conditions are assumed. This is an increase of approximately 21 (20.6) bushels per acre to offset the increase in production costs while the $6.00 price is held constant. The BE price is calculated to be $4.35 per bushel, an increase of $0.65 per bushel.
When the market price is varied from $6.70 to $4.70 per bushel (viewed left-to-right on the horizontal axis) at a yield of 190 bushels per acre, it is observed from Figure 3 that as price declines, more production is required to cover the increase cost of replanting.
Figure 3. Breakeven (BE) yield comparison across multiple price levels for replanting corn.
Figure 4 illustrates the required increase in BE yields from replanting a 190 bushel per acre potential field across multiple price levels. As the corn market price declines the required increase in BE yield increases from 18.45 (at a $6.70 price) to 26.30 bushels per acre (at a $4.70 price).
Figure 4. Required increase in BE yields from replanting costs in corn.
For information on soybean and corn enterprise budget and farm management economics, please refer to the LSU AgCenter’s website at https://lsuagcenter.com/topics/crops/soybeans/budg... and https://lsuagcenter.com/topics/crops/corn/budget .
Rasel Parvej, LSU AgCenter State Soil Fertility Specialist
Most of the corn acreage in Louisiana was injured by freezing temperature from March 19-20. At that time, most corn was at VE (emergence) to V2 stage (two leaves with visible collar) and therefore the growing point was below the soil surface. Corn’s growing point remains below the soil surface until V6 growth stage for most hybrids. Since frost injury is usually limited to aboveground plant parts, unless the temperature falls below 28°F, the growing point was most likely protected from freeze injury. However, temperatures may have reached the critical temperature of 28°F in some areas, so each field should be scouted to ensure that growing points are still viable. At this point producers need to wait 5-7 days or until visible growth is observed to assess stand quality and uniformity. Many producers are inquiring about applying some nitrogen (N) fertilizer to jump start new growth. The following things should be considered prior to applying N in frost injured corn field.
If you have any questions on loss mechanisms and why I suggest not applying all the N using urea at one short without incorporation please contact me at 479-387-2988 or mrparvej@agcenter.lsu.edu.
Ed Twidwell and Wink Alison – LSU AgCenter
Variety selection is an important decision that producers must make when establishing forages in pastures. Many varieties of forage crops are marketed in Louisiana and scientists with the Louisiana State University Agricultural Center periodically conduct variety trials with warm-season forages. This information is used to make suggestions each year concerning warm-season forages for producers to consider utilizing.
Suggested varieties listed are ones evaluated in Louisiana and found to perform satisfactorily. Suggested seeding rates are made assuming the use of good quality seed that meets the germination and purity seed standards as determined by the Louisiana Department of Agriculture and Forestry Seed Commission.
Warm-season perennial grasses grown in the Southern region are of tropical origin and grow mainly during the late spring, summer and early autumn. These grasses become dormant and remain unproductive during the winter months. The optimum planting date for these grasses is from March 1 to June 1, but they can also be planted anytime during the growing season when soil moisture is adequate.
Bermudagrass can be grown throughout Louisiana and is adapted to most soil types. Both seed-propagated and vegetatively propagated varieties are available. Seeded varieties should be planted at a rate of 5 to 8 pounds of hulled seed per acre. The hybrid varieties should be planted with enough plant material to give about 7,500 plants per acre.
Hybrids: Alicia, Brazos, Coastal, Grazer, Tifton 44, Tifton 85, Russell, Jiggs, Sumrall 007, and Little Phillip #1
Seeded: Common, Cheyenne II, Mohawk, Ranchero Frio, Sungrazer Plus
Bahiagrass is widely grown throughout Louisiana and is particularly adapted to well-drained sites and will persist on low fertility soils. It should be seeded at a rate of 15 pounds per acre.
Argentine, Pensacola, Tifton 9, UF Riata, TifQuik and AU Sand Mountain
Dallisgrass is very productive on alluvial soils and more fertile upland soils in Louisiana. Dallisgrass is noted for having poor seed quality. Seed germinates slowly, often taking four weeks or longer for emergence. There are no varieties of Dallisgrass; all seed is “common” and is imported from countries outside of the United States and seed availability is often limited. Dallisgrass should be seeded at a rate of 5 pounds per acre.
These grasses should be planted between April 15 and August 1. They will be killed by frost in the autumn. Specific variety suggestions for these species cannot be made because of insufficient data.
This species generally does best on well-drained, light, and upland soils. Pearl millet should be seeded at a rate of 25 pounds per acre if drilled and 30 pounds per acre if broadcast. This species does not cause prussic acid poisoning in livestock, but nitrate accumulation can cause toxicity under some circumstances.
This species generally does best on heavier soil types, although it can also be successfully planted on well-drained soils. Sorghum sudangrass should be seeded at a rate of 30 pounds per acre if drilled and 35 pounds per acre if broadcast. Nitrate accumulation or prussic acid can cause toxicity under some circumstances.
This species is best adapted to well-drained soil types. Seeds are planted at a rate of 15 to 20 pounds per acre in May or June. Establishment is slow and weed competition may be a problem. There are no varieties of Alyceclover available; only “common” seed is marketed.
This is a perennial legume that is adapted to well-drained soil types. It should not be planted on heavy soils that are prone to flooding or being water-logged for extended periods of time. Perennial peanuts would be better adapted in southern parts of
Louisiana, but have been shown to survive for several years at locations just south of I-20 in north Louisiana.
Two varieties that have been used in research trials in Louisiana are Arbrook and Florigraze. They should be planted at a rate of 60 to 80 bushels of rhizomes per acre from January 1 to March 15. Planting material is scarce, and producers may have to obtain their material from Georgia or Florida.
Specific variety suggestions for these species cannot be made because of insufficient data.
This species should be planted from April 15 to June 15 in south Louisiana and from May 1 to June 15 in north Louisiana. It can be planted at a rate of 8-12 pounds per acre if drilled and 15-20 pounds per acre if broadcast. It can also be planted at a rate of 6-8 pounds per acre if planted in 40-inch rows.
This species should be planted from March 1 to April 15. It should be planted at a rate of 12 to 20 pounds per acre planted in 30 to 40-inch rows.
The decision to “buy or not to buy” fertilizer is weighing on everyone’s mind. When the decision is made to purchase, hopefully the following will be helpful to you.
From an economic perspective, not all fertilizers are created equally. Therefore, it is important for us to compare fertilizers based on cost per acre. Let’s assume that we have these three fertilizers to choose from: 1) Urea – 46-0-0 with a cost of $1,010 per ton 2) Ammonium Nitrate – 33-0-0 with a cost of $897 per ton and
3) Ammonium Sulfate – 21-0-0 with a cost of $825 per ton. The knee jerk reaction is to purchase the least cost per ton option, but since the actual nitrogen content is quite different in these three sources, which fertilizer is the most economical if you want to apply 70 pounds of nitrogen per acre?
First, we must remember that neither of these three options are 100% nitrogen. Based on the guaranteed analysis, Urea is 46% nitrogen, Ammonium Nitrate is 33% nitrogen and Ammonium Sulfate is 21% nitrogen.
Next, calculate the pounds of fertilizer per acre you would need to apply to achieve the 70 pounds of nitrogen per acre in this scenario.
Urea (46-0-0)
70 lb. N per A ÷ 0.46/lb. of fertilizer = 152 lbs. needed per acre.
Ammonium Nitrate (33-0-0)
70 lb. N/A ÷ 0.33/lb. of fertilizer = 212 lbs. needed per acre.
Ammonium Sulfate (21-0-0-2)
70 lb. N/A ÷ 0.21/lb. of fertilizer = 333 lbs. needed per acre.
At slightly over 180 pounds per acre difference between the greater and lesser amounts is quite a bit, but what does this mean in terms of how light it makes your pocketbook? So, let’s calculate this based on what each of these will cost per acre, because that is what it all boils down to.
Urea @ $1,010 per ton/2,000 = $.505/lb. X 152 pounds needed per acre = $77 per acre
Ammonium Nitrate @ $897 per ton/2,000 = $.449/lb. X 212 pounds needed per acre = $95 per acre
Ammonium Sulfate @ $825 per ton/2,000 = $.413/lb. X 333 pounds needed per acre = $137 per acre
In this scenario, Urea is by far the best value per acre. You can use this math anytime you are purchasing a single nutrient (little more math involved when purchasing blended fertilizer). An important side note to keep in mind is that applications of urea-based fertilizers in the summer months can result in nitrogen loss due to volatilization. At least ½” of rain needs to be received in 3-4 days after a urea application to keep major nitrogen loss from occurring.
If we apply fertilizer when forage is actively growing, do a decent job of controlling broadleaf weeds, and conduct a cost- per-acre comparison of nutrient sources we can be more efficient with the money being spent on fertilizer. Other practices to consider to lower fertilizer costs are utilization of legumes in the forage system and recycling nutrients through grazing management.
Our Regional Horticulture Agents and specialists put together the Horticulture Hints for the Central Region in Louisiana. The Central Region Horticulture Hints can be found online by going to the Central Region Horticulture Hints Website. These are done quarterly and have great information on timely issues happening across our region. Great resource and information for any homeowner or commercial horticulturalist.
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