Wheat Variety Performance and Production Practices in Louisiana

Steve Harrison, Boyd Padgett, and Trey Price, LSU AgCenter scientists

Wheat acreage remained low in 2020. The season started off well but deteriorated in some parts of the state. The warm winter prevented vernalization of some varieties in the central and southern parts of the state, which resulted in poor yields. Scab continued to severely impact yield and grain quality. Fortunately, there is genetic resistance in a limited number of varieties and several fungicides that provide some suppression.Wheat prices are currently high and there is significantly more demand for seed this fall.Growers should be wary of planting varieties that do not have proven performance in a short seed year as some varieties are not adapted to Louisiana.

In an effort to assist producers, agents, and consultants in variety selection, the LSU AgCenter continues to evaluate varieties in official trials located on seven experiment stations. To access the complete 2020 Variety Performance Trial publication go to the 2020 Small Grain Performance Trials PDF page.

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. Fusarium head blight (FHB) epidemics were severe during the 2020 seasons due to environmental conditions favoring infection during flowering. 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.

Crop management:

Planting dates for Louisiana wheat depend on location and variety. For southern and central Louisiana, optimum planting dates range from November 1 through November 30. The optimum planting for northern Louisiana is slightly earlier, ranging from October 15 through November 15. Early-heading varieties should generally be planted after the mid-date, while late-heading varieties can be pushed a little on the early side of the planting window. The weather in north Louisiana is cooler in the fall and early winter, which slows growth and prevents excess winter growth. It is important that the wheat crop be well-established and fully tillered before the coldest part of the winter. Additionally, because of the cooler conditions, the threat from fall pests (Hessian fly, army worms and rust) is decreased earlier in the fall compared to south and central Louisiana. While these dates are the optimum planting window averaged over years, the timing will vary in some years depending on weather patterns. Additionally, if wheat cannot be planted within these optimum windows, planting later than the optimum window is usually better than planting too early. Early planting can result in greater insect and fall rust establishment and also makes plants more prone to spring freeze injury due to excessive fall growth and development. Planting too late (more than 14 days after the optimum window) can result in significant yield loss due to slow emergence, poor stands from seed rotting and a decreased tillering period, which results in fewer and smaller heads.

Wheat can be planted by broadcasting seed and incorporation into the soil; however, it is preferred that the seed be drilled. Drilling the seed increases the uniformity of depth and uniform emergence. Use recommended planting rates for drilled wheat (60 to 90 lb/A) or broadcast wheat (90-120 lb/A) of quality seed into a good seedbed with adequate moisture. This higher seeding rate should be used under conditions in which good germination or emergence is not expected, as occurs with late-planted wheat or heavy, wet soils. Late-planted seed should be planted at a higher seeding rate using a drill to ensure rapid, adequate and uniform emergence.

Good surface drainage is critical to successful wheat production.Saturated fields lead to diseases such as root rots and downy mildew, reduced tillering and vegetative growth, and decreased root development and nutrient utilization.Yields in wheat fields suffering from waterlogging stress are greatly reduced.Fields with marginal drainage should be ditched to ensure that water stands for a minimum time after heavy rainfall.

Nitrogen (N) fertilization of wheat can be a challenging aspect of production. Total N application should normally range from 90 to 120 pounds per acre, but this will vary depending on soil type and rainfall after applications. Timing of N application depends on several factors. The wheat crop needs adequate N in the fall and early winter to establish ground cover and properly tiller; however, excessive levels of fall N can result in rank growth and increased lodging potential, as well as a higher probability of spring freeze damage from early heading. If the wheat crop is following soybeans, soil residual or mineralized N should be adequate for fall growth, and no pre-plant N is needed. However, if the wheat 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. Any 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.

Phosphorus, K, and micronutrients should be applied in the fall based on soil test reports. All fertilizers applied as well as lime should be incorporated into the soil prior to planting. Required lime should be applied as soon as possible because it takes time for the lime to begin to neutralize the acidity of most soils. The application of sulfur is a growing concern in Louisiana production systems, with increasing deficiencies appearing every year. Oftentimes, early spring sulfur (S) deficiencies are mistaken for N deficiencies and additional S is not applied. Because sulfur is mobile, similar to N, the application solely in the fall may not be adequate. Supplemental applications of S with spring N applications are often warranted.

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

Weed Management Programs in Winter Wheat

Daniel Stephenson, LSU AgCenter Weed Specialist

Weed management in wheat is not extremely complicated, but subtle changes in the weed spectrum can really cause significant issues.There are not many herbicides labeled for use in wheat and only a few provide control of grassy and broadleaf weeds.Others are specific for grassy or broadleaf weeds.For example, Finesse, metribuzin, and Powerflex HL will control both most grassy and broadleaf weeds.Sharpen, Anthem Flex, Zidua, 2,4-D, dicamba, Osprey, Harmony Extra, and Axial XL are usually for either grassy weeds or broadleaf, although Anthem Flex, Zidua, and Osprey do provide control of broadleaf weeds.

Metribuzin has a major caveat that must be understood before applying it.Some wheat varieties are susceptible and some are tolerant to metribuzin.The LSU AgCenter, Mississippi State University, University of Arkansas, and University of Kentucky (probably others) have evaluated wheat tolerance to metribuzin in the past, so I suggest searching on the internet for this information or ask the person you purchased the seed from.That said, a postemergence application metribuzin in the fall provides excellent control of small grass and broadleaf weeds in wheat.

Another issue is ALS-inhibiting herbicide- and/or clethodim-resistant Italian ryegrass.In wheat, ALS-inhibiting herbicides that will control susceptible Italian ryegrass are Finesse, PowerFlex HL, and Osprey, so if resistance is present, then these herbicides may not be a good choice.Clethodim is utilized on many acres in Louisiana for glyphosate-resistant Italian ryegrass control in the spring at burndown.Unfortunately, many producers are reporting poor control with clethodim and the LSU AgCenter is investigating the possible presence of clethodim-resistant Italian ryegrass.Clethodim is an ACCase-inhibiting herbicide.In wheat, Axial XL is also an ACCase-inhibiting herbicide and is a great choice for Italian ryegrass control.Now, if clethodim didn’t control the Italian ryegrass previously, does that mean Axial XL won’t work either?I cannot say for sure, but I wouldn’t bet on it.So, Axial XL may not be a good option for Italian ryegrass control too.

In addition, if Finesse is applied preplant, preemergence, or postemergence, the rotation interval to cotton or soybean is 18 months.However, the interval is only 4 months for BOLT soybean and 6 months for STS soybean, so if Finesse is applied, the grower is locked into a BOLT or STS soybean variety.This issue is the primary reason I usually do not often suggest the use of Finesse.

Below are some scenarios and suggested herbicide programs in the absence or presence of the issues discussed above.Please read labels for use rates and application timing restrictions.

Preplant burndown:

• Glyphosate or paraquat plus Sharpen at 1 lb or 0.5 lb plus 1-2 oz/A.MSO and AMS must be used.

Fall POST:

• Anthem Flex at 2 to 4.5 oz/a depending upon soil type.80% of wheat must be emerged and 1-inch in height before application.Apply only to drill-seeded wheat.
• Zidua SC at 1.25 to 3.25 oz/A or Zidua WG 0.7 to 2 oz/A depending upon soil type.80% of wheat must be emerged and 1-inch in height before application.Apply only to drill-seeded wheat.
• Metribuzin at 2 to 3 oz/A.Apply only to drill-seeded wheat.
• PowerFlex XL at 2 oz/A plus nonionic surfactant.Will provide control of annual bluegrass when applied in the fall.

Spring POST:

• Harmony Extra at 0.45 to 0.9 oz/A plus nonionic surfactant.
• Axial XL at 16.4 oz/A
• 2,4-D at 0.5 to 1 lb/A.Apply after 3 tillers have formed, but before panicle initiation.

Remember to always read and follow the herbicide label instructions.If you have any questions, please call.

Daniel Stephenson – 318-308-7225

2020 LA Soybean Production Season Review

David Moseley, Daniel Stephenson, Sebe Brown, Boyd Padgett, Trey Price, Michael Deliberto, LSU AgCenter scientists

2020 Soybean Season Summary

The 2020 soybean season has been one for the history books.

In March, the USDA estimated Louisiana producers would increase soybean acres by 10% from 2019, for a total of 980,000 acres planted to soybean in 2020. Before the season could really get started, COVID-19 restrictions disrupted many operations. In addition, dry conditions in the south and wet conditions in the north slowed the planting progress in late March/early April. However, the progress increased in mid-April, and 68% of the crop had been planted by May 10^th. The planting progress during the optimum planting window was as high as 17% faster than in 2019. This efficiency did not remain after May 10^th as persistent rains prevented planting and caused some acres to be replanted; However, the LA soybean crop was 100% planted by June 21^st, just ahead of the five-year average. In October, the USDA increased their estimate of acres planted to 1.05 million acres.

The soybean crop condition was good for most of the growing season. Producers and parish agents reported they were optimistic for high yields, and the USDA rated the LA crop at least 85% good -excellent from July 5^th to August 23^rd.

Hurricane Laura hit landfall on August 29^th when the soybean crop was approximately 50% mature and 33% harvested. Parish agents estimated 13-16% of the crop was impacted, consisting mostly of light to heavy lodging. The economic impact was estimated to be approximately 1 to 1.5% yield reduction of pre-storm production.After Hurricane Laura, the crop rating dropped to 60% good - excellent.

In late September, Tropical Storm Beta dropped a lot of rain and delayed harvest in some areas. On October 9^th, Hurricane Delta hit landfall closely following the path of Hurricane Laura. When Delta hit, approximately 94% of the crop was mature and 90% harvested. Once again, parish agents estimated flood and wind damage caused an approximate 1% yield reduction of total pre-storm production.

On October 18^th, the USDA estimated 93% of the soybean crop had been harvested, equal to the five-year average. Furthermore, the harvested acre projection was 1.02 million acres with an estimated yield of 55 bu/A. The LA production forecast was 56.1 million bushels, up 36% from 2019.

Insect Pressure

Insect issues in soybean fields during 2020 were heavy across much of Louisiana. The winter of 2019-2020 was the second in a row of unseasonably warm temperatures that had very little impact on redbanded and native stink bugs. Clover began to appear in late fall across the state and began to bloom in South and Central Louisiana in February. This early green up and bloom of clover allowed for large populations of redbanded stink bugs to migrate into soybeans once the clover senesced.It was not uncommon for producers to make several applications for stink bugs (especially redbanded stink bugs) in 2020. Caterpillar populations were also higher in 2020 than years previous. Corn earworm infestations in soybeans from R1 to R4 were common throughout the state. Fields near corn were infested with large numbers of earworms for extended periods of time. Defoliating worms such as velvet bean caterpillars and soybean loopers were present in fields around Louisiana at economically damaging levels. According to several consultants, the level of defoliating worms in 2020 were higher than several previous decades.

Disease Pressure

Early in the season, southern blight and taproot decline were prevalent causing significant losses in some cases.Foliar diseases were not much of an issue until mid-season.Aerial blight, soybean rust, target spot, and Cercospora leaf blight were the major diseases impacting soybean in Louisiana.Hurricanes Laura and Delta provided conditions throughout the state that promoted disease development.Many texts, phone calls, and farm visits indicated that Cercospora leaf blight was particularly bad across the state, and in some cases played a role in preventing fields from being harvested.Green stem syndrome (influenced by variety, planting date, stinkbug pressure, disease pressure, and environmental stresses) was prevalent on some farms resulting in severe losses.Timely application of fungicides helped suppress diseases and preserved yield in some cases.Rains during the harvest season have caused seed quality issues in some cases.Looking forward to next season, producers should rotate fields to corn, cotton, sugarcane, or grain sorghum.

Weed Pressure

In 2020, weedy grasses, especially barnyardgrass, prickly sida (teaweed), and glyphosate-resistant pigweed were the most common weed issues in Louisiana.Difficulty in managing these weeds was often associated with a program consisting of only postemergence application(s) of glyphosate plus dicamba (Engenia, FeXapan, Tavium, or XtendiMax) in Xtend soybean.Weedy grass control was reduced following glyphosate plus dicamba because of antagonism – meaning the dicamba prevented the glyphosate from preforming the way it should on weedy grasses.Neither glyphosate nor dicamba have ever provided excellent control of prickly sida, so control was quite poor following their application.Control of glyphosate-resistant pigweed is highly influenced by the weed height at application, so dicamba applied to pigweeds bigger than 4-inches resulted in less than acceptable control.An additional, unexpected, herbicide application was usually needed to manage these pests.Clethodim or Assure II was applied for grass control.One to two applications of glyphosate plus a PPO-inhibiting herbicide like fomesafen or glyphosate plus Classic was needed for prickly sida, but sometimes that did not provide desired control.Everything was thrown at glyphosate-resistant pigweed because no herbicide provides good control of a big pigweed.Growers should plan to implement a program that includes a residual herbicide applied preemergence followed by a residual herbicide tank-mixed with their first postemergence application, usually 2-3 weeks after soybean emergence, to help manage weedy grasses, prickly sida, and glyphosate-resistant pigweed in 2021.Finally, above all, apply postemergence herbicides to weeds that are less than 3-inches tall.

Economics

Trade was the prominent theme dominating market news for the 2019/20 marketing year. That undertone continues to be persistent in the 2020/21 marketing year. The U.S/China Phase One agreement offers hope that U.S. soybeans would gain traction and displace Brazilian soybeans destined for China. Ultimately, that may or may not be the case, as strong export competition from Brazil (combined with a weak Brazilian real) signaled a reduction in U.S. soybean market share in China. China, whose swine sector has been ravaged by African Swine Fever, is beginning to show signs of economic recovery with added calls for diversifying shipment sources for soybeans to meet growing feed demand. As the 2020/21 marketing year progressed, soybean futures started to price in the smaller crop, additionally, export sales to China also helped to spur a rally for soybeans.

COVID-19 proved to be a major challenge for all sectors of both the U.S. and global economies. Logistical and governmental regulatory restrictions did affect agricultural supply chains. China bought cargoes of Brazilian soybeans for fall delivery, normally the peak U.S. shipping season to China. As the severity of the COVID-19 pandemic in Brazil continued to escalate, concerns about possible supply chains disruptions emerged in Brazil.

In October 2020, the USDA estimated the 2020/21 U.S. soybean crop at 4.268 billion bushels from 83.1 million acres sown. The estimated acres planted is down slightly from the March estimate of 83.5 million acres.

With strong export sales to China, the USDA raised its forecast of 2020/21 soybean exports to a record 2.2 billion bushels. The lower supply and higher export demand are forecast to reduce season-ending soybean stocks for 2020/21 by 170 million bushels to 290 million - a significant revision to the supply/demand balance sheet and supportive of soybean prices. The fast pace of early-season U.S. soybean shipments reflects unimpeded harvesting efforts and a record volume of new-crop sales. The latter is due largely to a sharp increase for export sales to China.

The tighter outlook prompted the USDA to boost its forecast of the 2020/21 U.S. average farm price to $9.80 per bushel from $9.25 last month. This is the first-time near-term soybean futures have reached the $10.00 mark since early June 2018. The dynamics behind the mid-August to mid-September price surge reflect a rebound in China purchases of U.S. soybeans and limited availability of exportable supplies in South America. Recovery of China’s pork industry from African Swine Fever has spurred imports by the Asian nation.

Recently, soybean futures are again finding support from strong Chinese demand and Brazilian planting delays. Prices have rallied about $1.75 since mid-August when the USDA initially began revising new crop bean production lower. If we go back to March and May, prices have gone up about 27%. The market has rallied from $8.30 per bushel to $10.50 more recently. Much of this occurred in the past month or two.

In a global perspective, the downsized U.S. crop and an increase for foreign use of soybeans in 2020/21 should continue to tighten global soybean stocks. For China, 2020/21 soybean imports are forecasted higher on account of strengthening demand.

Brazil has already begun planting their 2020/21 soybean crop. Progress is slow, however, due to a lack of rainfall. Dryness is unlikely to affect the soybean area sown in Brazil for 2020/21 but could delay the arrival of new-crop deliveries next year. A likely extension of the country’s tight old-crop supply has swelled Brazilian price quotes (relative to Chicago futures) for 2021 shipments. This signals that U.S. exporters may shoulder the burden of supplying China with soybean imports well into next year.