Spring Herbicide Applications on Winter Wheat – Part 2 Labeled Herbicides

Source: Purdue University (Edited)

If weed infestations are severe enough to require a herbicide application, the use of liquid nitrogen fertilizer solution as a carrier is a popular option for applying herbicides and topdressing the wheat crop in a single pass over the field.  Caution should be taken when using a liquid fertilizer as a herbicide carrier as moderate to severe crop injury can result, especially in saturated conditions.  Many post applied wheat herbicide labels allow for liquid nitrogen carriers, but require different rates and types of surfactants than if the herbicide was applied with water as the carrier.  Table 1 includes precautions to be taken when applying wheat herbicides using liquid fertilizer as a carrier; further details and directions can be acquired from the herbicide label.

Another consideration growers should take into account when planning early spring herbicide applications is the plant back restrictions to double crop soybeans.  A large percentage of the herbicides listed in Table 1, especially those with activity on Ryegrass and Brome, have soybean plant back restrictions greater than the typical three month time period between spring applications and double crop soybean planting.  The soybean plant back restrictions greatly reduce the number of options available to wheat producers who double crop soybeans after wheat.  Refer to Table 1 for more specific plant back timing restrictions.Click Here For Complete Table

Fertilizer License and Poultry Litter

Source: Glen Arnold, Field Specialist, OSU Extension (edited)

 

This winter there have been a few questions  about fertilizer license and spreading poultry manure.  According to Senate Bill 1 (SB 1), passed a few years ago, any farmer handling, receiving, or applying poultry litter (or any other manure) from a PERMITTED farm in Ohio must have either a fertilizer license or a Certified Livestock Manager certificate or be a Certified Crop Advisor.  If you have nay questions, call the Knox County Extension Office at 740-397-0401.

Nitrogen Application Timing for Weak Wheat Stands

Source: Ed Lentz, OSU Extension

Late-planted wheat fields had little opportunity for growth before cold and wet conditions moved into the area last November. Fall tiller production was limited because of early cold weather soon after planting. In addition, some wheat stands have been damaged this winter from lack of snow cover, standing water, saturated soils, ice sheets, and days of very cold temperatures.

In these situations, producers have asked whether they should apply nitrogen earlier to increase the number of spring tillers. Keep in mind, it is fall tillers that provide most of the yield in a wheat field. Heads developing from spring tillers generally are much smaller than heads from fall tillers.

In northern climates, the vegetative period of growth is much shorter than the other wheat regions of the country; thus, plants have a much shorter time to recover from winter damage. From my experience, producers will have limited success in improving yields of poor stands and stands with reduced-growth by applying nitrogen earlier. A producer may get a few more spring heads, but not enough to significantly change the yield situation. The earlier application will also significantly increase the risk of nitrogen loss. In fact, a producer may need to readjust their yield potential for these fields and reduce their total nitrogen rate accordingly.

Wheat does not need large amounts of nitrogen until jointing (Feekes GS 6), generally the latter part of April. Soil organic matter and/or nitrogen applied at planting generally provide sufficient nitrogen for early spring growth. Ohio research has shown no yield advantage for nitrogen applied before jointing. The longer the time between nitrogen application and jointing, the greater the risk for nitrogen loss. Nitrogen source will also affect the potential for loss. Urea-ammonium nitrate (28%) has the greatest potential for loss, ammonium sulfate the least, and urea would be somewhere between the two other sources.

Ohio research has also shown that yield losses may occur from nitrogen applied prior to green-up regardless of the nitrogen source. The level of loss depends on the year (losses would be smaller if the ground is not frozen or snow/ice covered). This same research did not observe a yield increase from applications made prior to green-up any year compared to green-up or Feekes GS 6 applications.  Keep in mind that green-up is a descriptive term and not a definable growth stage. My definition of green-up is when the new growth of spring has covered the dead tissue from winter giving the field a solid green color – thus, growing plants.

There is a legitimate concern that wet weather may prevent application of nitrogen at early stem elongation. Ohio research has shown a yield decrease may occur when nitrogen application is delayed until Feekes Growth Stage 9 (flag leaf fully emerged). Thus a practical compromise is to topdress nitrogen any time fields are suitable for application after initial green-up to Feekes GS 6. There is still a potential for loss even at green-up applications. To lessen this risk a producer may want to use a nitrogen source that has a lower potential for loss such as urea or ammonium sulfate. ESN (polymer-coated urea) would be another option but it needs to be blended with urea or ammonium sulfate to insure enough nitrogen will be available for the crop between Feekes GS 6 – 9. The source of nitrogen becomes less important as the application date approaches Feekes GS 6 (jointing). The percentage of urea and/or ammonium sulfate would need to be increased with ESN for application times closer to Feekes GS 6. A producer may want to consider the use of a urease inhibitor with urea if conditions are favorable for volatilization losses: warming temperatures, drying winds and no rain in the forecast for 48 hours.

A split application of nitrogen may also be used to spread the risk of nitrogen loss and to improve nitrogen efficiency; however, Ohio State University research has not shown a yield increase from this practice compared to a single application after green-up. In a split system, the first application should be applied no sooner than green-up. A smaller rate should be applied with the first application since little is needed by the crop at that time and the larger rate applied closer to Feekes GS 6.

In summary, some wheat fields look rough coming out of the winter. Applying nitrogen earlier may slightly increase the number of spring heads but probably not enough for a significant yield increase. The earlier application will increase the potential for nitrogen loss. University recommendation would be to topdress nitrogen when fields are suitable for application after initial green-up to early stem elongation.

Tar Spot – A “New” Corn Disease

Adopted from: CPN-2012 Corn – Tar Spot, Crop Protection Network

Initial symptoms of tar spot are brownish lesions on the leaves. Black, spore-producing spots appear later, making the leaf feel rough or bumpy. (Purdue Botany and Plant Pathology photo/Kiersten Wise)

Tar spot is a foliar disease of corn that commonly occurs throughout Mexico, Central America, South America, and the Caribbean. The disease was identified in the United States for the first time in 2015 in northern Illinois and Indiana. As of 2018, it has been confirmed in Iowa, Michigan, Wisconsin, Ohio, and Florida.  During the 2018 growing season, the prevalence and severity of the disease increased dramatically, and in some areas tar spot caused substantial yield losses.

In the United States, tar spot of corn is caused by the fungus Phyllachora maydis. The fungus produces small (0.2-0.8 inch), round to semi-circular, raised black structures called stromata.  In severe cases, stromata may also be observed on leaf sheaths and husks.  Tar spot severity on ear leaves at growth stage R5 (dent stage) can exceed 50 percent in susceptible hybrids when conditions are favorable for the disease.

Corn at any developmental stage is susceptible to infec­tion by the tar spot fungus when conditions are favor­able. Disease symptoms have been observed as early as the third-leaf (V3) growth stage in the United States. P. maydis overwinters on infested corn residue on the soil surface, which serves as a source of inoculum for the subsequent growing season. It is not known if P. maydis overwinters on or infects any other plant hosts in the United States.

Conditions that Favor Disease   In Latin America, cool temperatures (60-70°F) and high relative humidity (greater than 75 percent) favor tar spot development. In addition, disease incidence increases when there is at least seven hours of free moisture on the leaves due to rain, fog, or high relative humidity. However, it is not currently known what conditions favor the disease in the United States. In both 2015 and 2018, warm weather and periods of persistent rain and high humidity during the growing season likely favored the development and spread of the disease.

Continuous corn cultivation with minimum tillage practices, and high application rates of nitrogen fertilizer are also positively correlated with increased disease in Latin America. Although corn lines have been identi­fied in Latin America that have resistance to tar spot complex, U.S. observations indicate that most hybrids grown in the North Central region are susceptible to P. maydis (although they differ in susceptibility).

Yield Losses and Impact   Preliminary data from the Midwest indicate that severe tar spot outbreaks can reduce yield by more than 30 bushels per acre. Yield losses are a function of reduced ear weight, poor kernel fill, loose kernels, and vivipary (a condition in which the seed germinates while still on the cob). Observations also suggest that stalk rot and lodging are increased when tar spot severity is high. Severe tar spot also reduces forage quality.

Diagnosis  You can diagnose corn tar spot in the field by examining corn leaves for the presence of black, tar-like spots. To date, tar spot has been observed most often during mid-to late grain fill (growth stages R3-R6) and usually on leaves below or near the ear leaf. You can observe stromata in green and senesced tissues. Occasionally, you may also observe necrotic brown tissue surrounding the black structures, which produces a fisheye appear­ance.

Management  Most of what we know about tar spot has originated from Mexico and Central America. However, differences in the environments, fungal populations, hybrid genetics, and cropping systems may influence disease development in different areas. Our understanding of this disease in the United States is limited because of its very recent history.

However, several management practices may help reduce tar spot development and severity.

  1. Manage residue. Tilling fields buries infected residue and encourages it to decompose, which may help reduce the amount of overwintering tar spot inoculum.
  2. Rotate to other crops. This will allow residue to decompose and reduce the primary It is not yet known how many years it may take to sufficiently reduce inoculum.
  3. Avoid highly susceptible hybrids.
  4. Investigate fungicides. Some fungicides may reduce tar spot, however, we have little data about application timing that will provide an effective and economical response.  Efforts are underway to understand the biology and epidemiology of this disease, which may help formulate fungicide application decisions in the future.

 

Knox County Soybean Starter Fertilizer Trial

A BIG thank you to David & Emily Mitchem for allowing me to put my Soybean Starter Fertilizer trial on their farm this year!

 

The results are listed in the tables below.

The 2018 report is now available in both a print and e-version. To receive a printed copy, stop by the Knox County Extension office.  The e-version can be viewed and downloaded here at go.osu.edu/eFields.

Stalk Quality Concerns

Source: Dr.’s Peter Thomison, Pierce Paul, OSU

Poor stalk quality is being observed and reported in Ohio corn fields. One of the primary causes of this problem is stalk rot. Corn stalk rot, and consequently, lodging, are the results of several different but interrelated factors. The actual disease, stalk rot, is caused by one or more of several fungi capable of colonizing and disintegrating of the inner tissues of the stalk. The most common members of the stalk rot complex are Gibberella zeaeColletotrichum graminicolaStenocarpella maydis and members of the genus Fusarium.

The extent to which these fungi infect and cause stalk rot depends on the health of the plant. In general, severely stressed plants (due to foliar diseases, insects, or weather) are more greatly affected by stalk rot than stress-free plants. The stalk rot fungi typically survive in corn residue on the soil surface and invade the base of the corn stalk either directly or through wounds made by corn borers, hail, or mechanical injury. Occasionally, fungal invasion occurs at nodes above ground or behind the leaf sheath. The plant tissue is usually resistant to fungal colonization up to silking, after which the fungus spreads from the roots to the stalks. When diseased stalks are split, the pith is usually discolored and shows signs of disintegration. As the pith disintegrates, it separates from the rind and the stalk becomes a hollow tube-like structure. Destruction of the internal stalk tissue by fungi predisposes the plant to lodging.

Nothing can be done about stalk rots at this stage; however, growers can minimize yield and quality losses associated with lodging by harvesting fields with stalk rot problems as early as possible. Scout fields early for visual symptoms of stalk rot and use the “squeeze test” to assess the potential for lodging. Since stalk rots affect stalk integrity, one or more of the inner nodes can easily be compressed when the stalk is squeezed between the thumb and the forefinger. The “push” test is another way to predict lodging. Push the stalks at the ear level, 6 to 8 inches from the vertical. If the stalk breaks between the ear and the lowest node, stalk rot is usually present. To minimize stalk rot damage, harvest promptly after physiological maturity. Harvest delays will increase the risk of stalk lodging and grain yield losses and slowdown the harvest operation. Since the level of stalk rot varies from field to field and hybrids vary in their stalk strength and susceptibility to stalk rot, each field should be scouted separately.

Watersheds in Distress – New Reg’s Coming

Governor John Kasich signed an executive order on July 11, 2018 directing the Ohio Department of Agriculture (ODA) to “consider whether it is appropriate to seek the consent of the Ohio Soil and Water Commission (OSWC) to designate” certain watersheds “as watersheds in distress due to increased nutrient levels resulting from phosphorous attached to soil sediment.”  Since that time, ODA has submitted a proposed rule dealing with Watersheds in Distress.  Amendments were made to the proposed rule after evaluating the first set of public comments, and ODA is now resubmitting the rules package.

 Highlights of the Department’s revisions include the following changes:
  1. Make the proposed rule mirror the existing standards in the Revised Code that govern the application of manure and fertilizer on frozen, snow-covered and rain-soaked ground in the Western Basin.  These standards were enacted in Senate Bill 1 of the 131st General Assembly;
  2. Remove the manure application prohibition window for Grand Lake Saint Marys;
  3. Give the Director more flexibility in establishing the deadline for the submission and approval of nutrient management plans;
  4. Allow farmers to attest to the completion of their nutrient management plans by the deadline, while maintaining Ohio Department of Agriculture oversight to verify the completion and incorporation of a nutrient management plan.

A draft of the newly amended proposed rules is available here.

Evaluation of Adapt-N and FieldView Corn N Fertilizer Tools in Ohio

Source:  Dr. Steve Culman, OSU Extension

NutrientStar, an independent evaluator of nutrient management tools, has just released results testing the performance of two web-based tools that provide customized corn nitrogen fertilizer rates: Adapt-N and Climate FieldView. Both tools are available for farmers in Ohio to use for a fee.

NutrientStar conducted 61 trials over 3 years evaluating Adapt-N and 21 trials over 2 years evaluating FieldView in Ohio. A summary of findings is presented below.

Compared to ‘farmer normal practice’ using the tools produced a range of yield differences across trials and years in Ohio. Some trials yielded more grain using the tools (positive values) and some yielded less grain (negative values). When all trials within a year were averaged, both tools resulted in lower yields compared to farmer normal practices (8 – 41 bushels/acre less). Depending on the year, farmers lost on average between $6 – $131/ acre on their return to N fertilizer.

The results varied by state, with some states benefiting from the tools and other states not benefiting from the use of the tools. Unfortunately, these tools have not performed well in Ohio to date.

An alternative approach to deciding corn N fertilizer rates is to use the economic model that Ohio State University Extension endorses. This simple calculator is based on maximizing farmer profitability. It uses 3 inputs to determine at what point will additional N fertilizer not pay for itself with more yield. This free, publicly-available tool was recently updated with extensive on-farm trials in Ohio and can be found here: http://go.osu.edu/corn-n-rate

More information on Adapt-N evaluation: http://nutrientstar.org/tool-finder/adapt-n/

More information on FieldView evaluation: http://nutrientstar.org/tool-finder/climate-fieldview/

Early Yellowing Soybeans

Source: Dr Anne Dorrance, OSU Extension

Sudden Death Syndrome

Soybeans across the state range from ready to harvest to still flowering.  But in some fields, the yellowing was limited to pockets – some was sudden death syndrome or brown stem rot, charcoal rot, Phytophthora stem rot, and soybean cyst nematode.  There are some other early yellowing situations that we are still working on an accurate diagnosis, but yellowing in these cases may be linked to fertility issues and/or related to late flooding injury.  I think in 2018 we’ve observed just about everything, and it was all dependent on where in the state the soybeans were grown, how much rain occurred and when that rain fell, as well as the variety.  It did seem that we had calls on the same variety from multiple regions.

The heat this past weekend is also going to move the crop fairly fast. So if you haven’t driven by the earliest planted fields – this is the week to do so.  Sudden death syndrome is very widespread – but in most fields, it is limited to a scattering of plants throughout the wet areas.  The plants were not severely affected as most of the fields I visited were holding their leaves and not defoliating as quickly as I have observed for the most susceptible varieties. Late season Phytophthora stem rot is also present – in this disease, the plant wilts, holds its leaves and develops a brown canker that extends from the base of the plant up the stem.  Charcoal rot can also cause early yellowing or dying, and these symptoms were present last week in several areas of the state.  To distinguish this from other diseases, cut open the tap root and look for the black dots embedded in the tissue and lower stem.  When populations of soybean cyst nematode are high, plants will also mature earlier.  For cyst, you can dig up the plants, shake the soil off and see the small white pearls (females) on the roots.  Often we need a microscope as the cyst will turn tan to brown and becomes hard to see.

This round of late season scouting is important for variety selection, improving fertility applications for the fall, and prioritizing which fields to sample for soybean cyst nematode.  Let’s just hope the weather cools so we can get out of the trucks and walk into the fields!

It’s almost that time of year … Don’t forget to calibrate your yield monitor!

Remember the old adage … Garbage in = Garbage out. Many of us use our yield data to make additional management decisions on our farms such as hybrid or variety selection, fertilizer applications, marketing, etc. Data from an uncalibrated yield monitor can haunt us for many years by leading us into improper decisions with lasting financial affects. In today’s Ag economy we can ill afford any decision with adverse financial implications.

The two biggest reasons I usually hear for not calibrating a yield monitor are 1) I just don’t have time to do it or 2) I can’t remember how to do it without getting my manual out.  While I know it’s easy to criticize from “the cheap seats”, I would argue that this could be some of the most important time you spend in your farming operation each year.  Like many other tasks on our farm, the more we do it, the easier it gets.  Yield monitor data has so much value!  This data provides a summary (in term of yield) of every single decision you made on your farm during the past year.

Below is a calibration checklist created by Dr. John Fulton and Dr. Elizabeth Hawkins.

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