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C.O.R.N. Newsletter: 2024-14

  1. Battle for the Belt: Season 2 Episode 7- Soybean & Weed Competition

    Episode 7 of Battle for the Belt is now available: https://www.youtube.com/watch?v=F1FZlpe_QK8 
    In Episode 7, Dr. Eugene Law, a new Assistant Professor of Weed Ecology in the Department of Horticulture and Crop Science at Ohio State, discusses early season weed competition in soybean.

    Early season ragweed competition
    In the video from April 25, we are in the field at the Western Agricultural Research Station in an early planting weed control study observing seedling giant ragweed (Ambrosia trifida) establishment in March 25th planted soybeans. The ragweed at this point is outgrowing the soybean crop (Figure 1). Ragweed is resistant to many herbicides including ALS inhibitors, which are some of the best residual pre-emergence herbicides. The issue here is that ragweed seedlings have a greater tolerance to environmental stress compared to the soybean seedlings, and ragweed seedlings are coming up at the same time as the ultra-early planted soybeans. The resilience of ragweed is showcased by the frost conditions a few weeks ago (April 22), where the soybeans were heavily damaged in this field and the ragweed exhibited no injury. Early emerging weeds are generally adapted to colder and wetter conditions than crops, giving issues with early-season weed control if the weeds are resistant to or otherwise escape the herbicide programs being used. 

    x

    Figure 1. Ragweed seedling and frost-injured soybeans on April 25th at the Western Agricultural Research Station three days after initial frost.

    What can we do to manage weed competition?

    When soybeans are planted early, the normal burn down is applied even earlier and may not control the initial emergence of ragweed. Early planted soybeans can also have a reduced plant population due to frost, water damage, disease, or a combination of abiotic and biotic factors. Over time, the soybean can compensate for a low plant population with branching and does not always cause yield decline (depending on how severe stand loss is) but canopy closure takes longer and that is a major factor in the weed vs crop competition. Cultural practices that can be used to combat these issues include narrow row spacing or increasing seeding rate, to increase the speed of canopy closure to shade out the weeds. Another option is cover cropping, which provides a mulch that can slow down or prevent germination of weeds giving the soybean a head start if cover crops are managed properly.

    What’s happening in the field?

    Last week at the Western location, bean leaf beetle damage was found in the soybeans planted on March 25, but minimal damage was observed for the soybeans planted on April 16. Bean leaf beetle is common early in the growing season. For more information about bean leaf beetle in Ohio, please see this FactSheet: https://ohioline.osu.edu/factsheet/ENT-23#:~:text=The%20bean%20leaf%20beetle%20(BLB,found%20feeding%20on%20soybean%20nodules. The Western location received rain after planting the third date on Monday, May 6 (Table 1). Corn is at the V3/V4 growth stage and V2 growth stage for planting date 1 (March 25) and planting date 2 (April 16), respectively. Soybean is at V1 and VC for the first and second planting date, respectively. The fourth planting date is expected to occur in about 1-2 weeks.

     

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    Figure 2. Bean leaf beetle at the Western location in March 25th planted soybeans.


    The Wooster location had a little over two inches of rain last week. The stages for planting date one (April 22) were V1 for corn and VC for soybean. Planting date two (May 3) was germinated but has not yet emerged (https://www.youtube.com/shorts/IWS-309H-sw). Planting date three in Wooster will happen in the next 5-10 days.

    At the Northwest location, no planting has occurred due to wet conditions. We will plant when soil conditions become adequate, hopefully very soon. A summary of all planted sites and weather is presented in Table 2.

     Table 1. The planting date conditions for planting date three at the Western Location, 2024.

    Location

    Planting date

    2-inch soil temperature
     (at planting)

    Air Temperature

    (at planting)

    Western, Clark County

    May 6, 2024

    65°F

    63°F

     

     

    Table 2. Weekly weather conditions for planting dates one, two, and three at the Western location and planting date one and two at the Wooster Campus, with day of planting, soil, air temperature averages, and growing degree days (GDDS) from May 6 to May 12. Information from CFAES Weather System (https://weather.cfaes.osu.edu/).

    Location

    Precipitation

    (Inches)

    (May 6- May 12)

    2-inch soil temperature
     (May 6- May 12)

    Air Temperature

    (May 6- May 12)

    Planting date

    GDDs

    (Cumulative)

    Western,

    Clark County

     

     

    0.68

    Max: 76°F

    Mean: 66°F
    Minimum: 58
    °F

    Max: 85°F

    Mean: 63°F

    Minimum: 42°F

     

    March 25th

    April 16th

    May 3rd

     

     

    436

    327

    90

     

    Wooster, Wayne County

     

     

    2.42

    Max: 68°F

    Mean: 63°F
    Minimum: 57°F

    Max: 77°F

    Mean: 59°F
    Minimum: 38°F

     

     

    April 22nd

    May 3rd

     

    211

    106

     

     

     


     

  2. Lep Monitoring Network – Black Cutworm and True Armyworm Update # 4

    Our fourth week of monitoring for black cutworm and true armyworm resulted in a slight decline in the statewide average for both pests; however, some counties continue to have high trap numbers. These numbers indicate that both BCW and AMW moths are active in Ohio and may still be laying eggs.

    Black cutworm

    The statewide average decreased slightly 5.1 during the week ending May 5th to 4.2 for the week ending May 12th. Counties with high averages included Defiance (9.8), Hardin (8.7) and Van Wert (8.6) (Figure 1).  Adult moths lay eggs that hatch in 5 – 10 days. The larvae go through 6 instar stages over the next 28 – 35 days. Counties with high trap numbers should plan to scout for BCW larvae after corn is planted until V6 stage, especially in fields with a lot of broadleaf weeds. For more information on how to scout BCW please visit: https://aginsects.osu.edu/sites/aginsects/files/imce/ENT_35_14 BCW.pdf

    Black cutworm moth map - Week 4

    May 6th to May 12th, 2024

    x

    Figure 1. Average black cutworm (BCW) moths captured from May 6th to 12th. The bold number on the left indicates the average moth count for the week, followed by the standard number on the right which indicates the total traps set up in that county.

    True Armyworm

    Following a similar trend to BCW, the statewide average decreased for AMW from 9.4 moths for the week ending May 5th to 8.0 for the week ending May 12th. Counties with the highest averages included Van Wert (18.3), Henry (12.0) and Defiance (9.5) (Figure 2).  Plan to scout fields after corn is planted in counties that have had high averages, especially in fields that were previously planted to cover crops.  

    True Armyworm moth map - Week 4

    May 6th to May 12th, 2024

    x

    Figure 2. Average true armyworm (AMW) moths captured from May 6th to May 12th.  The bold number on the left indicates the average moth count for the week, followed by the standard number on the right which indicates the total traps set up in that county.

     

  3. Forage Maturity Across Ohio #2

    As the spring continues to progress so do our forages. The past week has resulted in a jump in alfalfa height and the estimated %NDF for fields around the state. It is a similar case for predominately grass fields as they beginning to lose quality and head out. To get the most out of a forage crop it is important to assess the forage quality to drive harvest decisions.

    An easy method used to estimate timely alfalfa quality is Predictive Equations for Alfalfa Quality (PEAQ). The PEAQ method uses the tallest and the most mature alfalfa stems in a pure stand to determine %NDF. For example, if the tallest alfalfa stem in the sampling area is 31 inches and the most mature alfalfa stem observed is in the bud stage, the %NDF estimation is 40.1. The protocol for the PEAQ method can be found here as well as a video explanation here.

    The following table indicates the maturity, height, and estimated %NDF of alfalfa fields from counties across the state for the week of May 7th to May 13th.

    County

    Maturity

    Height (inches)

    Estimated %NDF

    Auglaize

    Vegetative

    20-28

    31.3-36.8

    Crawford

    Vegetative

    18-21

    29.9-32

    Defiance

    Vegetative

    19-24

    30.6-34

    Fulton

    Vegetative

    24-27

    34-36.1

    Mercer

    Bud

    26-32

    36.6-40.8

    Paulding

    Vegetative

    25-28

    34.7-36.8

    Wayne

    Vegetative/ Early Bud

    18-32

    29.9-39.6

     

  4. Statewide Alfalfa Weevil Population Update #4

    Around the state, there have been a lot of alfalfa fields either sprayed or harvested, in the pursuit of controlling alfalfa weevil and making the first cutting of the year a quality one. If you have a field that hasn’t been treated or scouted yet, it is still worth the effort to assess the field prior to first cutting.

    The following table indicates the average alfalfa height and alfalfa weevil population for the couple of fields scouted in each county for the week of May 7th-May 13th.

    County

    Alfalfa Height (inches)

    Average Larvae Count per Stem

    Auglaize

    20-28

    0.2

    Defiance

    19-24

    0.03

    Mercer

    26-32

    0.2

    Paulding

    25-28

    0.17

    Ross

    14-31

    0.06

    Wayne

    18-32

    0.4

     

    Every county scouted this week saw a reduction in the alfalfa weevil population as spray controls and harvesting diminished the overall pest presence. As the window of concern about alfalfa weevil begins to close there are a few things to keep in mind. If a spray control is used be sure to follow the pre-harvest interval that is required. If there was a substantial alfalfa weevil population prior to first cutting be sure to scout for feeding on alfalfa regrowth 4-5 days after harvest. Alfalfa weevil feeding can significantly slow regrowth and decrease alfalfa production.

    If you would like to learn more about the scouting process, reference the article written earlier this year “Scouting Early Alfalfa Weevil Activity” and this 5-minute forage team video “Alfalfa Weevil Scouting”. If you have any questions reach out to an author or your local extension office.

     

     

  5. Corn & Soybean Planting Updates: Delays and Potential Yield Impacts and Recommendations

    Planting Progress. According to the USDA National Agricultural Statistics Service, 36% of corn and 27% of soybean were planted by May 12, 2024. For comparison, in 2023, 22% of corn and 25% soybean were planted by this time of the year. Although planting progress seems to be ahead of last year (especially for corn), planting progress is unequal across the state, with southern and central areas of Ohio further along than northern areas due to limited days suitable for field work (Figure 1).

    Figure 1. Corn and soybean emergence in Ohio for early planted crop.

    c x

    Potential Yield Impact. For both corn and soybean, timely planting is important to maximize yield. In our soybean trials, we’ve seen as much as a 0.5 bu/acre/day for each day planted after the end of April (Hankinson et al., 2015; Rattalino Edreira et al., 2017). Similarly, for corn, yield can decrease up to 1.75 bu/acre/day if planted after the end of April (Nielsen, 2022; Roekel & Coulter, 2011).

    Although early planting is important, planting into good soil conditions is also very important, especially for corn due to its lower compensation capacity. In general, timely planting is important, but crops planted passed the recommended planting window (early May) can still yield well, depending on weather conditions later in the growing season. Planting under poor conditions can be detrimental to crop yields.

    In previously conducted soybean planting date research, soybean planted in April and May yielded 8 to 26% more than soybean planted in late June when water was not limiting during the R3 to R5 soybean growth stages, initial pod through initial grain fill (Colet et al., 2023). In last year’s planting date research (Battle for the Belt Results - 2023), soybean yield was ≥81 bu/acre when planted by mid-May, with yields declining to 69-71 bu/acre when we delayed planting to June 8 at the Northwest and Western Ohio locations. In Northeast Ohio, soybean yield was greatest when we planted on May 11 (57 bu/acre), with yields declining to 52 bu/acre and 46 bu/acre when planting was delayed to May 30 and June 21, respectively. For corn, Northwest 2023 results showed that maximum yields (~240 bu/acre) were achieved with earlier plantings (April 12, April 26, May 11); lower yields documented for May 25 (~200 bu/acre) or June 8 (~175 bu/acre). For northeast Ohio, maximum yields were achieved with corn planted on May 11 (235-250 bu/acre); earlier (April) or later (June) plantings decreased yields by about 20-70 bu/acre. Due to abnormally wet conditions followed by a dry spell in 2023’s planting window at the Western site, corn yielded best (>210 bu/acre) when planting was delayed to May 25 or even stretched into June 8.

    Recommendations for Delayed Corn Planting. If corn planting is delayed, some adjustments that can be considered include:

    • Target plant population and seeding rates. Depending on the hybrid and production environment, recommended plant populations (or final stand) can range from 26,000 to 34,000+ plants per acre. Factoring in germination and emergence losses is necessary when estimating seeding rates. Due to better crop germination and emergence conditions with delayed planting dates (e.g., warmer temperatures), stand establishment can be better under later plantings.
    • Relative maturity. Longer relative maturities are more conducive to higher yields. As planting is delayed, the overall yield potential goes down and there is concern about whether late maturing hybrids will mature before frost. When planting late, consider shorter season hybrids that will reach physiological maturity before the first killing frost. Generally, 115-day hybrids yield best when planted in April or early May. For delayed plantings (late May or June), shorter season hybrids tend to yield best under normal conditions. From 2023 research results, recommended corn relative maturities are shown in Table 1.  

    Table 1. Optimum relative maturity for corn planted across five dates in Northwest, Northeast, and West Central Ohio (Table adapted from Battle for the Belt Results - 2023).

    Region

    Planting Date

    Optimum Relative Maturity

    Northwest OH

    Apr 12

    115-day

    Apr 26

    115-day

    May 11

    115-day

    May 25

    107 & 115-day

    June 8

    100-day

    Northeast OH

    Apr 14

    115-day

    Apr 27

    115-day

    May 11

    107 & 115-day

    May 30

    100 & 107-day

    June 21

    100 & 111-day

    West Central OH

    Apr 13

    111-day

    Apr 27

    107-day

    May 11

    115-day

    May 25

    107-day

    June 8

    115-day

     

    Recommendations for Delayed Soybean Planting. If soybean planting continues to be delayed, some of the adjustments that can be made:

    • Target plant population. When soybeans are planted in May, 100,000 to 120,000 plants/acre is recommended as the target plant population. If soybean planting is delayed to June, the recommended target population increases to 130,000 to 150,000 plants/acre.
    • Row spacing. Regardless of planting date, we recommend planting soybean in narrow rows (7.5 to 15-inches). Across the U.S., studies have shown narrow rows outyield wider rows (≥30 inches) 69% of the time due to earlier canopy closure that enables more light interception to drive photosynthesis (Soybean National Recommendations). Narrow row spacing becomes even more important as soybean planting is delayed. The later in the growing season soybeans are planted, the greater the yield increase due to narrow rows.
    • Relative maturity. Relative maturity has little effect on yield for plantings made during the first three weeks of May, but the effect can be large for later plantings. As planting is delayed, yield potential goes down and there is concern about whether late maturing varieties will mature before frost. When planting late, the ‘rule of thumb’ is to plant the latest maturing variety that will reach physiological maturity before the first killing frost. The reason for using late maturing varieties for late planting is to allow the plants to grow vegetatively as long as possible to produce nodes where pods can form before vegetative growth is slowed due to flowering and pod formation. Recommended relative maturity ranges for June and July planting are shown in Table 2.

    Table 2. Recommended relative maturity ranges for soybean varieties planted in June and July in Northern, Central, and Southern Ohio (Table adapted from the Ohio Agronomy Guide).

    Region

    Planting Date

    Suitable Relative Maturity

    Northern OH

    June 1-15

    3.2-3.8

    June 15-30

    3.1-3.5

    July 1-10

    3.0-3.3

    Central OH

    June 1-15

    3.4-4.0

    June 15-30

    3.3-3.7

    July 1-10

    3.2-3.5

    Southern OH

    June 1-15

    3.6-4.2

    June 15-30

    3.5-3.9

    July 1-10

    3.4-3.7

     

    Follow more planting and other Agronomic Crop Updates via C.O.R.N. Newsletter or visit the Ohio State Agronomy YouTube channel.

     

     

     

     

    References

    Colet, F., Lindsey, A.J., and Lindsey, L.E. 2023. Soybean planting date and seeding rate effect on grain yield and profitability. Agronomy Journal, 115, 2289-2297. https://acsess.onlinelibrary.wiley.com/doi/10.1002/agj2.21434

    Hankinson, M.W., Lindsey, L.E., and Culman, S.W. 2015. Effect of planting date and starter fertilizer on soybean grain yield. Crop, Forage & Turfgrass Management, 1, 1-6. https://acsess.onlinelibrary.wiley.com/doi/10.2134/cftm2015.0178

    Nielsen, R.L. 2022. The Planting Date Conundrum for Corn. Corny News Network, Purdue Univ. Available at: https://www.agry.purdue.edu/ext/corn/news/timeless/PltDateCornYld.html.

    Rattalino Edreira, J.I., Mourtzinis, S., Conley, S.P., Roth, A.C., Ciampitti, I.A., Licht, M.A., Kandel, H., Kyveryga, P.M., Lindsey, L.E., Mueller, D.S., Naeve, S.L., Nafziger, E., Specht, J.E., Stanley, J., Staton, M.J., and Grassini, P. 2017. Assessing causes of yield gaps in agricultural areas with diversity in climate and soils. Agricultural and Forest Meteorology, 247, 170-180. https://www.sciencedirect.com/science/article/pii/S0168192317302265#fig0030

    Van Roekel, R.J. and Coulter, J.A. 2011. Agronomic Responses of Corn to Planting Date and Plant Density. Agronomy Journal, 103: 1414-1422. https://doi.org/10.2134/agronj2011.0071

  6. Ryegrass Control and Cover Crop Termination

    Spring weather patterns have led to variability in planting progress across the state. Some parts of Ohio have made strides thanks to early warm temperatures and dry soils, and others have hardly started due to untimely, excessive rainfall. A couple of questions have been recurring this spring, related to the control of ryegrass (annual/Italian) in burndown situations, and the effective termination of cover crops.

    Weed scientists generally don’t recommend the use of annual ryegrass as a cover crop, as it is an aggressive species, tends to escape control tactics, and can quickly become a weed issue in grain crops. Ryegrass can pop up in crop fields due to cover crop control failures, roadside grass plantings, or contaminated seed.

    There are some general guidelines to improve the control of ryegrass. These include:

    • Herbicide applications before plants reach 6-8 inches in height lead to the most consistent control.
    • Use 1.5-2.5 lbs ae per acre of glyphosate for a complete kill. Adding 1 oz of saflufenacil (Sharpen) or 1 oz of tiafenacil (Reviton) can increase control of annual ryegrass, and higher rates don’t necessarily improve control.
    • Control is most effective when plants are actively growing, and nighttime temperatures remain above 45F for 2 to 3 day prior to and after application.
    • There have been reports of poor control with glyphosate in Ohio, and we know resistance is an issue in areas across the region. Where control issues have occurred, mixtures of gramoxone + metribuzin or atrazine + 2,4-D or dicamba can control plants smaller than 6 inches. Clethodim + glyphosate is an option ahead of soybean, although control can be slow, especially under cool weather conditions.
    • Group 5 herbicides (atrazine and metribuzin) can antagonize glyphosate efficacy on ryegrass when applied in tank mixtures.
    • Preliminary data from UK suggests that 28% UAN as a carrier for glyphosate may result in poor control of ryegrass.
    • Ryegrass control is most effective in the fall. Where not adequately killed with either a fall or spring burndown application, control options for large plants present at the time of planting are limited.

    The speed of small grain (cereal rye, wheat, barley, etc.) cover crop termination has also been in question this spring. Here’s some general reminders about cover crop termination:

    • Weather conditions at the time of application and shortly after can influence efficacy and speed of kill. Cool, cloudy conditions and low nighttime temperatures can slow the rate of control.
    • It may take 14-21 days for a complete kill in these conditions.
    • Increased glyphosate rates may be necessary on taller cover crops and in cool conditions.
    • Grass cover crop species are most effectively terminated with glyphosate alone or in combination with saflufenacil.
    • Broadleaf cover crop species are most effectively terminated with mixtures of glyphosate + 2,4-D, dicamba, or saflufenacil.
    • Check herbicide labels for crop rotation restrictions when planning cover crop termination applications, especially for Group 1 and 4 herbicides.

     

     

Crop Observation and Recommendation Network

C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.

Contributors

Alan Leininger (Educator, Agriculture and Natural Resources)
Allen Gahler (Educator, Agriculture and Natural Resources)
Alyssa Essman (State Specialist, Weed Science)
Amanda Bennett (Educator, Agriculture and Natural Resources)
Amber Emmons, CCA (Water Quality Extension Associate)
Barry Ward (Program Leader)
Ben Torrance (State Statistician)
Bruce Clevenger, CCA (Field Specialist, Farm Management)
Caden Buschur (Educator, Agriculture and Natural Resources)
Clifton Martin, CCA (Educator, Agriculture and Natural Resources)
Clint Schroeder (Program Manager)
Curtis Young, CCA (Educator, Agriculture and Natural Resources)
Don Hammersmith (Program Assistant, Agriculture and Natural Resources)
Eric Richer, CCA (Field Specialist, Farm Management)
Eugene Law, PhD (Assistant Professor)
Gigi Neal (Educator, Agriculture and Natural Resources)
Glen Arnold, CCA (Field Specialist, Manure Nutrient Management )
Grant Davis, CCA (Educator, Agriculture and Natural Resources)
Greg LaBarge, CPAg/CCA (Field Specialist, Agronomic Systems)
Horacio Lopez-Nicora (State Specialist, Soybean Pathology)
Jacob Winters (Educator, Agriculture and Natural Resources)
John Barker (Educator, Agriculture and Natural Resources)
Jordan Penrose (Educator, Agriculture and Natural Resources)
Ken Ford (Educator, Agriculture and Natural Resources)
Kendall Lovejoy (Educator, Agriculture and Natural Resources)
Kyle Verhoff (Educator, Agriculture and Natural Resources)
Laura Lindsey (State Specialist, Soybean and Small Grains)
Lee Beers, CCA (Educator, Agriculture and Natural Resources)
Les Ober, CCA (Educator, Agriculture and Natural Resources)
Mark Badertscher (Educator, Agriculture and Natural Resources)
Mike Estadt (Educator, Agriculture and Natural Resources)
Mike Gastier, CCA (Educator, Agriculture and Natural Resources)
Osler Ortez (State Specialist, Corn & Emerging Crops)
Rachel Cochran, CCA (Water Quality Extension Associate, Defiance, Van Wert, Paulding Counties)
Ryan McMichael (Educator, Agriculture and Natural Resources)
Rylee Kay Puthoff (Educator, Agriculture and Natural Resources)
Sarah Noggle (Educator, Agriculture and Natural Resources)
Seth Kannberg (Educator, Agriculture and Natural Resources)
Stephanie Karhoff, CCA (Field Specialist, Agronomic Systems)
Ted Wiseman (Educator, Agriculture and Natural Resources)
Trevor Corboy (Educator, Agriculture and Natural Resources)
Wayne Dellinger, CCA (Educator, Agriculture and Natural Resources)

Disclaimer

The information presented here, along with any trade names used, is supplied with the understanding that no discrimination is intended and no endorsement is made by Ohio State University Extension is implied. Although every attempt is made to produce information that is complete, timely, and accurate, the pesticide user bears responsibility of consulting the pesticide label and adhering to those directions.

CFAES provides research and related educational programs to clientele on a nondiscriminatory basis. For more information, visit cfaesdiversity.osu.edu. For an accessible format of this publication, visit cfaes.osu.edu/accessibility.