Soybean Vegetative Growth Stages- VC vs V1

By: Laura Lindsay, OSU

Across the state, soybean growth and development is variable, ranging from early vegetative stages to flowering. However, there has been some confusion regarding the identification of the VC and V1 growth stages. This confusion is mostly due to two definitions of V1…that actually mean the same thing. The Fehr and Caviness Method (1977) is based on the number of nodes that have a fully developed leaf, whereas Pederson (2009) focuses more on leaf unrolling so that the leaf edges are no longer touching. The VC definition for both methods is the same, but the differences start to appear between the methods at V1. Fehr and Caviness define V1 as “fully developed leaves at unifoliolate nodes,” which also means that there is “one set of unfolded trifoliolate leaves unrolled sufficiently, so the leaf edges are not touching.” This second definition is common in extension publications (Pedersen, 2009).

Soybean growth stages are described in the OSU Corn, Soybean, Wheat, and Forages Field Guide (available for purchase here: https://extensionpubs.osu.edu/corn-soybean-wheat-and-forages-field-guide-pdf/). A visual guide to soybean staging is available as a pdf from Dr. Shawn Conley at the University of Wisconsin-Madison (https://coolbean.info/library/documents/2017_Soybean_GrowthDev_Guide_FINAL.pdf).

What a Difference a Year Makes in the Weather

By: Aaron Wilson, OSU

Things change quickly when it comes to weather and climate. Recall 2019, a record wet start to the year for many across Ohio, only to see 26% of the state enveloped in moderate drought conditions by October. Though not nearly as wet as last year, it has been wetter than average through the first five months of 2020.

Figure 1: Multi-sensor observed month-to-date precipitation ending on June 22, 2020. Figure from the Midwestern Regional Climate Center (https://mrcc.illinois.edu).

Things change quickly when it comes to weather and climate. Recall 2019, a record wet start to the year for many across Ohio, only to see 26% of the state enveloped in moderate drought conditions by October. Though not nearly as wet as last year, it has been wetter than average through the first five months of 2020.

Since our calendar flipped to the meteorological summer on June 1, however, precipitation has all but turned off across western and northwest Ohio (Figure 1). Most areas here have seen an inch or less of rainfall. Community Collaborative Rain, Hail and Snow Network (CoCoRaHS) observers in Ada, Napoleon, and Lima have only recorded 0.18”, 0.29”, and 0.40” of rainfall so far for the month! With warm summer conditions, this has led to intense evaporation rates and rapidly drying soils. To submit a report of drought impacts for your area, consider the Drought Impact Reporter. For more information on recent climate conditions and impacts, check out the latest Hydro-Climate Assessment from the State Climate Office of Ohio.

Figure 2: Forecast precipitation for the next 7 days. Valid from 8 pm Monday June 23, 2020 through 8 pm Monday June 30, 2020. Figure from the Weather Prediction Center https://www.wpc.ncep.noaa.gov/).

Continue reading

Changes in status of dicamba product labels for Xtend soybeans – a recap

DSource: Dr. Mark Loux, OSU

 

Ohio Department of Agriculture: Dicamba use in Ohio ends June 30, 2020

 

On June 3, the US 9th Circuit Court of Appeals issued a decision in a case concerning the use of dicamba on Xtend soybeans.  This decision voided the labels for XtendiMax, Engenia, and FeXapan that allows use on Xtend soybeans.  Tavium was not included in this decision, because it was not approved for use when the case was initially filed.  Several excellent articles covering this decision can be found here on the OSU Ag Law blog (https://farmoffice.osu.edu/blog).  EPA stated on June 8, providing further guidance about what this decision means for the use of dicamba for the rest of this season.  The gist of this decision was the following:

“EPA’s order addresses sale, distribution, and use of existing stocks of the three affected dicamba products – XtendiMax with vapor grip technology, Engenia, and FeXapan.

  1. Distribution or sale by any person is generally prohibited except for ensuring proper disposal or return to the registrant.
  2. Growers and commercial applicators may use existing stocks that were in their possession on June 3, 2020, the effective date of the Court decision. Such use must be consistent with the product’s previously-approved label, and may not continue after July 31, 2020.”

ODA subsequently issued a statement regarding the registration and use of these products in Ohio, stating that any application must happen before July 1, 2020.  Partial text from this statement:

“The registration of these products (XtendiMax, FeXapan, and Engenia) in Ohio expires on June 30, 2020. After careful evaluation of the court’s ruling, US EPA’s Final Cancellation Order, and the Ohio Revised Code and Administrative Code, as of July 1, 2020, these products will no longer be registered or available for use in Ohio unless otherwise ordered by the courts.

Continue reading

True Armyworm Infestations

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.

Continue reading

Distribution of Waterhemp and Palmer Amaranth in Ohio

Source: Dr. Mark Loux

The maps that accompany this article show our current knowledge of waterhemp and Palmer amaranth distribution in Ohio.  These are based on information from a survey of OSU Extension County Educators, along with information we had from samples submitted, direct contacts, etc.  We still consider any new introductions of Palmer amaranth to be from an external source (brought in from outside Ohio) – hay or feed, infested equipment, CRP/cover/wildlife seedings.  Palmer is not really spreading around the state, and as the map shows, we have had a number of introductions that were immediately remediated.  The number of counties where an infestation(s) is being managed is still low, and within those counties, the outbreak occurs in only a few fields still.  Waterhemp is much more widespread in Ohio and is spreading rapidly within the state from existing infestations to new areas via equipment, water, animals, etc.  We do not have Ag Educators in all counties, and even where we do, infestations can occur without us knowing about them.  Feel free to contact us with new information to update the maps.

Among the weed photos sent to the Agronomy Team members for identification, a fair number lately has been for the purposes of “pigweed” identification.  “Pigweed” as used here can refer to waterhemp, Palmer amaranth, spiny amaranth, Powell amaranth, and redroot/smooth pigweed (these two are mostly the same for ID/control purposes).  It’s almost impossible to tell these apart when they are very small, but this gets easier by the time they are 4 inches tall.  Waterhemp and Smooth/redroot pigweed are still the most common.  Waterhemp is smooth all over with a somewhat elongated leaf with smooth edges, and leaves sometimes can be a darker and glossier green than pigweed.  Smooth/redroot pigweed will have a hairy/rough stem (more defined as it gets larger), with relatively nonglossy leaves that are widest in the middle with “rougher” edges.  Various resources are available to help with identification, including our pigweed ID fact sheet and Youtube video.  Identification of pigweeds is not necessarily straight forward, so feel free to contact your local extension educator or OSU weed scientists (loux.1@osu.edu or ackley.19@osu.edu) for help with identification.

ODA Statement on Dicamba – Official Statement Regarding the Use of Over-the-Top Dicamba Products

Source: C.O.R.N. Newsletter

Official Statement Regarding the Use of Over-the-Top Dicamba Products

 

 

On June 3, 2020, the U.S. Court of Appeals for the Ninth Circuit rendered a decision which vacated the federal registrations of three of the four dicamba products that had previously been approved for use on dicamba-tolerant (DT) soybeans. This decision has caused tremendous uncertainty for soybean producers and pesticide dealers during an agronomically critical time of year.  It is estimated that around 40 to 50 percent of the soybean crop planted in Ohio are dicamba tolerant varieties. The specific products impacted are:  XtendiMax with VaporGrip Technology, Engenia Herbicide, and DuPont FeXapan with VaporGrip Technology. Tavium plus VaporGrip Technology for use on DT soybeans was not covered by this ruling.

In response to the decision, on June 8, 2020, the United States Environmental Protection Agency (US EPA) issued a Final Cancellation Order that outlines specific circumstances under which existing stocks of the three affected dicamba products can be used. The registration of these products in Ohio expires on June 30, 2020.  After careful evaluation of the court’s ruling, US EPA’s Final Cancellation Order, and the Ohio Revised Code and Administrative Code, as of July 1, 2020 these products will no longer be registered or available for use in Ohio unless otherwise ordered by the courts.

While use of already purchased product is permitted in Ohio until June 30, 2020, the Court’s decision and US EPA’s order makes further distribution or sale illegal, except for ensuring proper disposal or return to the registrant. Application of existing stocks inconsistent with the previously approved labeling accompanying the product is prohibited.  If you have questions about returning unused products, please reach out to your pesticide dealer’s representative.

For additional questions, please email pesticides@agri.ohio.gov or call 614-728-6394, and visit ODA’s website for updates.

Corn and Soybean Seedling Blights

Source: Dr. Anne Dorrance, OSU

Low stands or poor development of plants is, unfortunately, a common occurrence for fields that were planted in many regions of Ohio with heavy soil or are poorly drained soil.  Symptoms include skips, missing plants, or dried up and brown seedlings.  There may also be, wilting plants with and rotten, brown, decaying spots or lesions on the roots. Now is an excellent time to scout stands and check to be sure that the fields are not just crusted over – and that the seeds and seedlings that are there are still healthy.

While there, dig up a few of the affected plants, if the roots are brown and soft, the seedling will die eventually or be very weak.  So don’t count them as part of your total stand.  On soybeans check to see if there are nodules, the corky looking knobs on the roots that help legumes fix nitrogen.  The cold, wet weather does not favor nodulation, so this may take a bit longer, for now, native Rhizobium spp. to get a foothold in the plants.  Once the plants have nodules, they will recover and grow.  On corn, the root (mesocotyl) between the young seedling and the seed, should be white.  If it is dark brown or soft, this will also be a weakened plant.  Some pathogens, if the environment is right, will continue to multiply and grow to kill the seedling.

For management, improving soil drainage, and having at least two ingredients in the seed treatment mixture targeting water molds (Pythium and Phytophthora) are necessary for the challenging areas in Ohio that have a history of replanting.  If you do have to replant, take a look at what the seed treatment package is and note what is in the mix.  The one caution, though, is if the field was submerged for more than 24-48 hours (Ponding), this is flood injury, and there are no seed treatments for this.

Is It Nitrogen or Sulfur Deficiency Symptoms

Source: Dr. John Sawyer, Iowa State Univ.

Yellowing of corn plants early in the season can be confusing to diagnose. And in some conditions there may be a period of time after corn emergence where small corn just does not look good. There can be a number of causes for plant yellowing. An example is the description in a recent ICM Blog by Alison Robertson (Anthracnose leaf blight prevalent in corn fields). Other reasons for yellow corn tissue are varied such as waterlogged soils, cold temperatures, herbicide issues, potassium deficiency (typically older leaf margins), etc. Two reasons that can be confusing due to similar plant symptoms are nitrogen (N) and sulfur (S) deficiency.

Nitrogen deficiency. Classic symptom description is yellowing of lower (older) leaves, from the leaf tip to the base down the midrib.

Sulfur deficiency. Classic symptom description is yellowing of new leaves (in the whorl, sometimes with interveinal striping), with lower (older) leaves remaining uniform green (Figure 1).

However, both N and S are tied together due to several common physiological process, therefore, early growth symptoms can be similar. Examples including overall leaf and plant yellowing, spindly plants, and interveinal striping. These similar symptoms most often occur when plants are small and there is severe deficiency (low soil supply and no fertilization). Also, plant response from fertilizer application can be quite similar for N and S, that is, good growth and green plants with uniform coloration (Figure 2). Sulfur does not move as readily in plants as N, so symptoms should differentiate on different plant parts. However, with young plants, early onset of symptoms, and with large and prolonged deficiency, such differentiation may not happen (Figures 2 and 3). One way to determine if an early season deficiency is N or S is to hand apply some S and N fertilizer to different areas and see if the plants green up.

Click here for complete article.