Herbicide options for burndown of existing weeds prior to planting of no-till wheat include glyphosate, Gramoxone, Sharpen, and dicamba. Among these, the combination of glyphosate and Sharpen probably provides the best combination of efficacy on marestail, flexibility in application timing and residual control. Dicamba labels have the following restriction on preplant applications – “allow 10 days between application and planting for each 0.25 lb ai/A used”. A rate of 0.5 lb ai/A would therefore need to be applied at least 20 days before planting. We do not know of any 2,4-D product labels that support the use of 2,4-D prior to or at the time wheat planting. There is some risk of stand reduction and injury to wheat from applications of 2,4-D too close to the time of planting. Liberty and other glufosinate products are also not labeled for use as a burndown treatment for wheat. Sharpen should provide limited residual control of winter annuals that emerge after herbicide application, and the rate can be increased from 1 to 2 oz/A to improve the length of residual. Gramoxone should also effectively control small seedlings of marestail and other winter annuals. Be sure to use the appropriate adjuvants with any of these, and increase spray volume to 15 to 20 gpa to ensure adequate coverage with Sharpen or Gramoxone.
There are several effective postemergence herbicide treatments for wheat that can be applied in November to control these weeds, in fields where preplant burndown treatments are not used. The most effective postemergence treatments include Huskie, Quelex, or mixtures of dicamba with either Peak, tribenuron (Express etc), or a tribenuron/thifensulfuron premix (Harmony Xtra etc). We discourage application of 2,4-D to emerged wheat in the fall due to the risk of injury and yield reduction.
The purpose of the Ohio Wheat Performance Test is to evaluate wheat varieties, blends, brands, and breeding lines for yield, grain quality, and other important performance characteristics. This information gives wheat producers comparative information for selecting the varieties best suited for their production system and market. Varieties differ in yield potential, winter hardiness, maturity, standability, disease and insect resistance, and other agronomic characteristics. Selection should be based on performance from multiple test sites and years.
In fall 2019, wheat was planted at four out of the five locations within 10 days of the fly-free date. Due to poor soil conditions, wheat was planted in Wood County 21 days after the fly-free date; however, wheat grain yield averaged 99.5 bu/acre at that location. Wheat entered dormancy in good to excellent condition. Early season wheat growth and development were slower than previous years due to cool temperatures and above average precipitation. Harvest conditions were favorable and harvest dates average. Results from Union County were not included in this report due to extreme field variability caused by high rainfall. Overall, grain test weight averaged 58.8 lb/bu (compared to an average test weight of 55.0 lb/bu in 2019). Across the Wood, Wayne, Darke, and Pickaway locations, grain yield averaged 93.8 bu/acre.
Source: Andy Michel, Curtis Young, CCA, Kelley Tilmon, OSU
As you scout your fields this week be on the lookout for this pest!
We received many reports of true armyworm infestations in wheat, barley, and corn. These are black or green caterpillars with stripes along the side and orange heads. In the spring, true armyworm moths migrate from the south and lay eggs in grasses such as forage and weed grasses, winter wheat and barley, and rye cover crops. When the eggs hatch, the larvae can significantly damage wheat and barley before then moving to young corn. Usually, moth flights occur in April, but we may have had a second peak the first or second week of May—it’s likely the caterpillars feeding now are from this later flight. Right now, wheat, barley, and corn should be inspected for true armyworm populations. Armyworms like to hide during the day and feed at night, so scouting should occur at dusk or dawn, and/or on cloudy days.
Corn: True armyworm in corn cause the most damage when planted in no-till grassy fields, such as a rye cover crop. In this case, after feeding on the cover crop, the caterpillars shift onto the emerging corn. The name armyworm comes from the caterpillars’ behavior of migrating en masse from one location to another. Thus, one should pay particular attention to cornfields adjacent to wheat fields that may have supported a high armyworm population, especially the first several rows into the cornfield. As the wheat matures and dries down, it could stimulate the caterpillars to move.
One may only need to treat the edge of the field closest to the wheat field from which the caterpillars are marching. If armyworms are found in a cornfield, check for the percentage of plants damaged in 5 sets of 20 plants. If more than 10% of the stand has feeding damage, it may indicate a large infestation, and the field should be re-checked in a few days to see if defoliation is increasing. If defoliation has increased and plants have two or more caterpillars per corn seedling, an insecticide application may be necessary. However, if most larvae are longer than 1 inch, then much of the feeding is complete as the caterpillars will begin to pupate. Also, look for the presence of diseased (black and shriveled) or parasitized caterpillars (having a few or several small, white egg cases on their body)—if found, do not include them in your counting.
If defoliation exceeds 50%, even a rescue treatment may not recover the field without a significant impact on yield. According to the Handy Bt Trait Table (https://agrilife.org/lubbock/files/2020/02/BtTraitTable_FEB_2020.pdf), only the Vip3A (e.g., Viptera) Bt trait is effective against true armyworm. Insecticidal seed treatments may offer some control but can be overwhelmed with high populations. Plus, insecticidal seed treatments last only about 4-6 weeks after planting.
Between planting in the fall and Feekes 4 growth stage (beginning of erect growth) in the spring, winter wheat is vulnerable to environmental stress such as saturated soils and freeze-thaw cycles that cause soil heaving. All of which may lead to substantial stand reduction, and consequently, low grain yield. However, a stand that looks thin in the spring does not always correspond to lower grain yield. Rather than relying on a visual assessment, we suggest counting the number of wheat stems or using the mobile phone app (Canopeo) to estimate wheat grain yield.
Wheat stem count method. Wheat stems (main stem plus tillers) should be counted at Feekes 5 growth stage (leaf sheaths strongly erect) from one linear foot of row from several areas within a field.
Canopeo mobile phone app method. Canopy cover should be measured at Feekes 5 growth stage using the mobile phone application, Canopeo (http://canopeoapp.com). After accessing the app, hold your cell phone parallel to the ground to capture three rows of wheat in the image and take a picture. The app will convert the picture to black and white and quantify (as a percentage) the amount of green pixels in the image. For example, the screen shot here shows 44.86% canopy cover. (Keep in mind, this app will quantify anything green in the image. So, if you have a weedy field, the weeds will also be quantified in the canopy cover estimate.) Continue reading →
Source: Andy Michel, Laura Lindsey, Pierce Paul, OSU
With the autumn rapidly approaching, wheat planting is likely to begin soon. Planting after the Hessian fly free date remains the best chance to avoid issues with insects and diseases, as well as helping ensure good agronomic quality. Some benefits of the fly free date:
Hessian Fly: Adults of the Hessian fly lay eggs in emerging wheat. These eggs then hatch into small larvae that feed before spending the winter as a flaxseed. The early autumn feeding will stress the young wheat plant right before the winter, resulting in stunted and wilted plants. Very little egg laying occurs after the fly free date, which helps to limit infestation. Wheat varieties with resistance against the Hessian are available, in addition to seed treatments, which can help limit damage.
Aphids: Two main aphids infest wheat in Ohio: the English grain aphid and the bird cherry-oat aphid. These aphids rarely cause economic injury on wheat from feeding. However, they can transmit several viruses that can severely impact wheat including Barley Yellow Dwarf virus. These aphids do not only feed on wheat, but several other grasses that serve as natural sources of viruses. If wheat is planted too early, and emerges before the aphids overwinter or stop feeding, they can be early transmitters of viruses. Although seed treatments could help kill the aphids, they may survive long enough to transmit the virus to the plant. Any transmission in the autumn would likely serve as a local source in the following spring.
Other foliar diseases: Although not directly related to the Hessian Fly, planting after the fly free date also helps to reduce the early establishment of leaf diseases like Stagonospora leaf blotch and powdery mildew. Planting date is indirectly linked to spore production by fungi that cause these diseases and infection of young plants. The earlier you plant, the more spores are available, and the more suitable (warmer) conditions are for infection. Fall infections often leads to more damage and greater yield loss in the spring, especially of susceptible varieties are planted and not protected with a fungicide at Feeks 8 (flag leaf emergence). As conditions become cooler after the fly free date, pathogens that cause leaf diseases become last active, and as such, are less likely to infect plants.
The purpose of the Ohio Wheat Performance Test is to evaluate wheat varieties, blends, brands, and breeding lines for yield, grain quality, and other important performance characteristics. This information gives wheat producers comparative information for selecting the varieties best suited for their production system and market. Varieties differ in yield potential, winter hardiness, maturity, standability, disease and insect resistance, and other agronomic characteristics. Selection should be based on performance from multiple test sites and years.
In fall 2018, wheat was planted at three out of the five locations within two weeks of the fly-free date. Due to poor soil conditions, wheat was planted in Marion and Wayne County 16 and 23 days after the fly-free date, respectively. Wheat entered dormancy in good to excellent condition. Early season wheat growth and development were slower than the previous years due to cool temperatures and above average precipitation. However, harvest conditions were favorable and harvest dates average. Results from the Marion County were not included in the 2019 report due to extreme field variability caused by high rainfall. Overall, grain test weight averaged 55.0 lb/bu (compared to an average test weight of 55.5 lb/bu in 2018). Across the Wood, Wayne, Darke, and Pickaway locations, grain yield averaged 85.9 bu/acre.
Source: Christy Sprague, Michigan State University
The challenging conditions this spring have left many fields unplanted. Glyphosate- and multiple-resistant horseweed (marestail) dominates a majority of these fields. Horseweed and other weeds in these unplanted fields need to be controlled prior to setting seed to prevent future weed problems. To help determine some of the more effective options for horseweed control, we sprayed several treatments two weeks ago on 2 feet tall horseweed. Common lambsquarters, common ragweed and prickly lettuce were also present in this field. Below is a compilation of pictures of these treatments and a summary of the results.
Horseweed control results
Roundup PowerMax (glyphosate) alone was ineffective at controlling a majority of the horseweed plants in this field (Figure 1A), indicating this population is highly resistant to glyphosate. Glyphosate-resistant horseweed is extremely common in many Michigan fields and glyphosate alone should not be used. The addition of 2,4-D ester at 1 pint per acre (pt/A) or 1 quart per acre (qt/A), Enlist One at 1 pt/A or Clarity (dicamba) at 1 pt/A to Roundup PowerMax improved horseweed control. However, controlling horseweed with these treatments only ranged from 60–70% 14 days after treatment (Figure 1B). These treatments will not likely result in complete control of horseweed.
The addition of 2,4-D or dicamba also improved common lambsquarters and common ragweed control over Roundup PowerMax alone. While these may be some of the more inexpensive treatments, they were not the most effective and caution should be taken if 2,4-D ester or any of the dicamba formulations are used. Off-target movement by drift or volatility, especially under high temperature conditions and when sensitive crops are in the area, can occur these herbicides.
Figure 2. Glyphosate-resistant horseweed control with (A) Liberty (glufosinate) at 32 fl oz/A plus AMS and (B) Sharpen at 1 fl oz/A plus Roundup PowerMax at 32 fl oz/A plus MSO plus AMS, 14 days after treatment. Photo by Christy Sprague, MSU.
The most effective treatments to control glyphosate-resistant horseweed were Liberty (glufosinate) at 32 fluid ounces per acre (fl oz/A) plus AMS (Figure 2A), or Sharpen at 1 fl oz/A or 2 fl oz/A plus Roundup PowerMax at 32 fl oz/A plus MSO plus AMS (Figure 2B). These treatments resulted in greater than 95% control of horseweed, common lambsquarters, common ragweed and prickly lettuce. A higher rate of Liberty (glufosinate) at 43 fl oz/A can also be used.
Initial control of glyphosate-resistant horseweed with Gramoxone 3L (new formulation) at 2.67 pt/A plus surfactant was 80%. However, by 14 days after treatment, horseweed started to regrow (Figure 3). Controlling common lambsquarters, common ragweed and prickly lettuce ranged from 70–75%.
Figure 3. Glyphosate-resistant horseweed control with Gramoxone plus surfactant, 14 days after treatment. Photo by Christy Sprague, MSU.
Two additional treatments we examined included disking and mowing. Mowing reduced overall weed biomass, however it also removed the primary growing point and as horseweed started to regrow, additional shoots were produced. If mowing, multiple passes throughout the season will likely be required. A onetime mowing would likely be more beneficial later in the season prior to flowering and seed set. Tillage or disking did provide good horseweed control, however it will likely take multiple passes to keep the fields clean throughout the season.
Additional considerations
All these treatments were applied under good growing conditions (plenty of moisture and heat) and resulted in good herbicide activity. As weeds continue to grow and begin to flower, the effectiveness of these treatments will likely be reduced. Additionally, depending on the weed species, there could possibly be new emergence later in the season.
Crop rotation restrictions also need to be considered when choosing one of these herbicide treatments for horseweed and other weed control. Sharpen, 2,4-D and dicamba all have residual activity and could cause injury to certain cover crops and winter wheat if rotation restrictions are not followed. Winter wheat should not be planted earlier than one month after applying dicamba or 2,4-D (Enlist One). Sharpen at 1 or 2 fl oz/A can be applied any time before planting winter wheat. There is a 70-day rotation restriction between Liberty applications and planting winter wheat. Consult individual herbicide labels.
Wheat harvest is now underway. What is the nutrient value of the straw? The nutrient value of wheat straw is influenced by several factors including weather, variety, and cultural practices. Thus, the most accurate values require sending a sample of the straw to an analytical laboratory. However, “book values” can be used to estimate the nutrient values of wheat straw. In previous newsletters, we reported that typically a ton of wheat straw would provide approximately 11 pounds of N, 3 pounds of P2O5, and 20 pounds of K2O.
The nitrogen in wheat straw will not immediately be available for plant uptake. The nitrogen will need to be converted by microorganisms to ammonium and nitrate (a process called “mineralization”). Once the nitrogen is in the ammonium and/or nitrate form, it is available for plant uptake. The rate of which mineralization occurs depends on the amount of carbon and nitrogen in the straw (C:N ratio). The USDA reports a C:N ratio of 80:1 for wheat straw which means there are 80 units of carbon for every unit of nitrogen. Mineralization rapidly occurs when the C:N ratio is ≤ 20:1. At a C:N ratio of 80:1, mineralization will be much slower. (For comparison, corn stover is reported to have a C:N ratio of 57:1.) Rate of mineralization is also influenced by soil moisture and temperature. Since mineralization is a microbial-driven process, mineralization will be slowed (halted) in the winter when temperatures are cold. Thus, no N credit is given for wheat straw since it is not known when the N will mineralize and become available to the following crop.
Besides providing nutrients, straw has value as organic matter, but it is difficult to determine the dollar value for it. Removal of straw does lower soil potash levels. If straw was removed after heavy rainfall, some of the potash may have leached out of the straw, lowering the nutrient value of the straw. However, a soil test should be done to accurately estimate nutrient availability for future crops.
Source: Barry Ward, Leader, Production Business Management & Director, OSU Income Tax School
Production costs for Ohio field crops are forecast to be largely unchanged from last year with slightly higher fertilizer and interest expenses that may increase total costs for some growers. Variable costs for corn in Ohio for 2019 are projected to range from $356 to $451 per acre depending on land productivity. Variable costs for 2019 Ohio soybeans are projected to range from $210 to $230 per acre. Wheat variable expenses for 2019 are projected to range from $178 to $219 per acre.
Returns will likely be low to negative for many producers depending on price movement throughout the rest of the year. Grain prices used as assumptions in the 2019 crop enterprise budgets are $3.60/bushel for corn, $8.20/bushel for soybeans and $4.25/bushel for wheat. Projected returns above variable costs (contribution margin) range from $150 to $308 per acre for corn and $144 to $300 per acre for soybeans. Projected returns above variable costs for wheat range from $102 to $202 per acre (assuming $4.25 per bushel summer cash price).
Return to Land is a measure calculated to assist in land rental and purchase decision making. The measure is calculated by starting with total receipts or revenue from the crop and subtracting all expenses except the land expense. Returns to Land for Ohio corn (Total receipts minus total costs except land cost) are projected to range from $23 to $182 per acre in 2018 depending on land production capabilities. Returns to land for Ohio soybeans are expected to range from $84 to $254 per acre depending on land production capabilities. Returns to land for wheat (not including straw or double-crop returns) are projected to range from negative $2 per acre to a positive $143 per acre.
Total costs projected for trend line corn production in Ohio are estimated to be $753 per acre. This includes all variable costs as well as fixed costs (or overhead if you prefer) including machinery, labor, management and land costs. Fixed machinery costs of $66 per acre include depreciation, interest, insurance and housing. A land charge of $187 per acre is based on data from the Western Ohio Cropland Values and Cash Rents Survey Summary. Labor and management costs combined are calculated at $69 per acre. Returns Above Total Costs for trend line corn production are negative at -$120 per acre.
Total costs projected for trend line soybean production in Ohio are estimated to be $518 per acre. (Fixed machinery costs – $52 per acre, land charge: $187 per acre, labor and management costs combined: $45 per acre.) Returns Above Total Costs for trend line soybean production are also projected to be negative at -$76 per acre.
Total costs projected for trend line wheat production in Ohio are estimated to be $488 per acre. (Fixed machinery costs: $52 per acre, land charge: $187 per acre, labor and management costs combined: $39 per acre.) Returns Above Total Costs for trend line wheat production are also negative at -$137 per acre.
These projections are based on OSU Extension Ohio Crop Enterprise Budgets. Newly updated Enterprise Budgets for 2019 have been completed and posted to the OSU Extension farmoffice website: https://farmoffice.osu.edu/farm-management-tools/farm-budgets
Between planting in the fall and Feekes 4 growth stage (beginning of erect growth) in the spring, winter wheat is vulnerable to environmental stress such as freezing temperatures with limited snow cover, saturated soils, and freeze-thaw cycles that cause soil heaving. All of which may lead to substantial stand reduction.
However, a stand that looks thin in the spring does not always correspond to lower grain yield. Rather than relying on a visual stand assessment, farmers should estimate the yield potential of their winter wheat crop by counting stems, before deciding whether a field should be destroyed. An alternative method to evaluate wheat stand is fractional green canopy cover (FGCC). Fractional green canopy cover can be used to measure the canopy surface area using the mobile device application Canopeo. The app can be downloaded for free here: http://www.canopeoapp.com.
Figure 1. Measurement tool used to consistently count the number of stems in one foot of row.
Wheat Stem Count Methods: Wheat stems (main stem plus tillers) should be counted at Feekes 5 growth stage (leaf sheaths strongly erect) from one linear foot of row from several areas within a field (Figure 1).
Figure 2. Winter malting barley image analyzed for fractional green canopy cover with the Canopeo mobile device application.
Fractional Green Canopy Cover Methods: Fractional green canopy cover should be measured at Feekes 5 growth stage using the mobile device application, Canopeo (http://www.canopeoapp.com). The camera should be held at a height to capture three rows of wheat in the image (Figure 2).
After counting the number of wheat stems or measuring FGCC, Table 1 can be used to estimate wheat grain yield. For example, if an average of 51 stems is counted from one foot length of row, the predicted grain yield would be 100 bu/acre. Similarly, if the average FGCC measurement was 35%, the predicted grain yield would be 100 bu/acre.
Herbicide options for burndown of existing weeds prior to planting of no-till wheat include glyphosate, Gramoxone, Sharpen, and dicamba. Among these, the combination of glyphosate and Sharpen probably provides the best combination of efficacy on marestail, flexibility in application timing and residual control. Dicamba labels have the following restriction on preplant applications – “allow 10 days between application and planting for each 0.25 lb ai/A used”. A rate of 0.5 lb ai/A would therefore need to be applied at least 20 days before planting. We do not know of any 2,4-D product labels that support the use of 2,4-D prior to or at the time wheat planting. There is some risk of stand reduction and injury to wheat from applications of 2,4-D too close to the time of planting. Liberty and other glufosinate products are also not labeled for use as a burndown treatment for wheat. Sharpen should provide limited residual control of winter annuals that emerge after herbicide application, and the rate can be increased from 1 to 2 oz/A to improve the length of residual. Gramoxone should also effectively control small seedlings of marestail and other winter annuals. Be sure to use the appropriate adjuvants with any of these, and increase spray volume to 15 to 20 gpa to ensure adequate coverage with Sharpen or Gramoxone.
