Author Archives: David Holshouser

About David Holshouser

David serves as Associate Professor & Extension Agronomist at Virginia Tech’s Tidewater Agricultural Research and Extension Center. He provides leadership for agronomic extension and research programs that lead to profitable and environmentally-responsible agriculture.

Soybean Seed Development & Late-Season Decisions

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The soybean crop is rapidly moving along. Normally the R6 or late-seed filling stage will last about 3 weeks, although that time will shorten with late planting. Most of this year’s crop has reached that stage with the exception of late-maturing varieties planted double-crop after wheat harvest.

The crop has made only 50% of it’s yield at the beginning of this stage and about 75% of its yield 8 to 12 days into the stage. Only after the crop reaches physiological maturity is 95 to 100% of the yield been made. If stress such as we are having now occurs during this time, seed size will be small and some seed will abort in the pods.

The dry weather that we’ve recently experienced is speeding up development, aborting seed, and small seed size will likely occur. Areas that have received recent rainfall may not experience this. Unfortunately, yield may not be as good as they appear – the pod load will be deceiving in dry areas.

Aborted seed due to drought

There are still some late-season decisions that need to be made in some parts, such aa harvest aid timing or late-season insecticide application.

So when can you apply a harvest aid to control weeds or possibly speed up development? First you need to follow the label. Different harvest aids have different requirements. Many are not allowed/legal until R7. If you however select a harvest aid that can be applied in the late-R6 stage, I suggest waiting until at least half of the leaves on the plant have dropped and half of those remaining are turning yellow. This is only within a few days until R7; about 15 days after beginning R6. Most of the yield should have been made by this time. Any application before this time could affect yield.

What if you are experiencing insect defoliation? Both Mexican bean beetle and soybean looper are causing some problems in different parts of Virginia. First, is it worth treating for defoliating pests at this late stage? If you have not entered the R6 stage and are still at R5, then severe defoliation (>15%; >10% for late-planted, poor growth) could greatly impact yield. But what if you are in the R6 stage? This will depend on 1) presence of the pest and how much defoliation you have experienced; 2) how long before you are at a “safe” stage, where you’ve reached most of your yield potential; and 3) the amount of leaf area – the more the better.

Our Pest Management Guide thresholds indicate that we can tolerate up to 35% defoliation for soybean that contains fully-developed seeds (with good growth/high leaf area; less for late-planted, poor growth). But we also need to consider how long before we reach R7. If you are half-way through R6, then you are probably “safe” and don’t need to spray, depending on how fast the defoliation is occurring and the number of pests present.

However, if your are only a few days into R6, the decision is much harder. As you can see from the above diagram, we’ve only made 50 to 75% of our yield by this time. With excess leaf area (we have this in many parts of Virginia this year), you can tolerate a good bit of defoliation, even at this stage. The real questions are how long before I reach the “safe” stage and how fast is the insect pest defoliating the crop. As I stated earlier, the dry weather is speeding up maturity; so, time to maturity could be reduced by several days. The crop could be getting less valuable with time. If this is the case, I would not expect a benefit of an insecticide application. But what if the crop is not under stress? As an agronomist, I lean towards protecting crop yield. But, these questions can only be answered on a field by field basis. And you’ll need all the information that you can get, from various sources.

Virginia Ag Expo is Thursday, Aug 4

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I want to remind everyone that the Virginia Ag Expo, Virginia’s largest field day, is next Thursday, Aug 4.  The Expo is an educational, marketing, and social event that farmers and agribusiness look forward to each year.  It moves from one location to another each year and strives to showcase the diversity of Virginia Agriculture.  Our host this year is Mill Creek Farms and the event will be located at Camden Farm, which is located near Port Royal, right off of Highway 17 in Caroline County.

Precision for Profits is the theme for the 2022 Virginia Agricultural Expo. There will be a wide variety of agribusinesses present (currently over 85 exhibitors) showcasing the latest equipment, technology, goods, and services.  Virginia Cooperative Extension will be working with NRCS to highlight the diversity of soils on this farm and the high potential for precision agriculture practices.  Field plots are once again a walking, go-at-your-own-pace tour designed to fit your interest and schedule. Breakfast and Lunch will be catered by the vendors shown below.

The Virginia Ag Expo is jointly sponsored by the Virginia Grain Growers and Virginia Soybean Associations, in Cooperation with Virginia Cooperative Extension.

This event is FREE to the public. Click the link below to let us know you are coming!

https://fb.me/e/2MiwlXRvw

Cooler Soil Temperatures = Delayed Soybean Emergence

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The upcoming weekend rainfall (our meteorologists seem assured that it’ll be widespread) should greatly help parts of Virginia that are short on or getting short of topsoil moisture and position us perfectly for a good start to the soybean growing season.

However, with the rainfall comes cooler soil temperatures. Below are predictions for 4-inch soil moisture and soil temperature over the next 10 days from Orange (one of the coolest parts of Virginia) and Suffolk (one of the warmest parts). As you see, soil temperatures will plummet from relatively warm (>60o) to nearly 50o or less over the weekend. While soybean seed will germinate and emerge in a reasonable amount of time at 60O, germination and emergence will be very slow when temperatures dip below this.

Therefore, heed my suggestion and make sure that you have a good fungicide seed treatment on anything that you are planting now or early next week.

Below is the fungicide efficacy chart from our Pest Management Guide. The main diseases that we need to concern ourselves with are Rhizoctonia and Fusarium sp. If in wet soils, Pythium and Phytophtora sp. could also be a problem with slow-emerging soybean. Be sure to protect a slow-emerging crop with a fungicide containing the active ingredients that provide good to excellent control of the appropriate disease.

Soybean Planting Tips

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Many may have already planted. Some have stopped planting other crops such and peanut and cotton due to cool soils and started planting soybean instead. Regardless, an advantage of soybean is that it tolerates a wide range of planting dates. I’ve found no advantage to planting soybean before May and have seen little yield penalty from planting as late as the first week of June, under most conditions. There are advantages to planting early and planting late, but that is not the subject of this post. Contact me for more detailed discussion on this matter-it will take more that a few comments.

With that said, I’ve always preferred May planting due to less risk of frost damage and slow emergence that is common with earlier planting. Still there are big differences in management when planting in early- versus late-May. Here I’ll review a few of these.

  • Plant earliest maturing varieties first, then move to later maturing varieties. This will spread risk and harvest dates. We have however observed that early-planting and/or early-maturing varieties work better under productive soils/fields. If planting on poor soils/unproductive fields, later-maturing varieties will extend the growing season and push the critical pod- and seed-filling stages to less stressful times of the year.
  • Always plant into moisture. But don’t plant more than 1 inch deep when soils are cool or emergence will be delayed substantially. One-half to 3/4 of an inch is adequate. For later planting dates when soils are warm, one can plant as deep as 1.5 inches and get rapid emergence.
  • If planting into cool soils (usually before mid-May), use a good fungicide seed treatment. It could take 10 days or more for the soybean to emerge; plenty of time for soil-born seedling diseases to attack.
  • A final plant population of 70 to 100 thousand plants per acre is usually adequate for full-season plantings. This means that 95 to 130 thousand seed per acre is enough, depending on expected emergence. Our research and in other states have observed that less seed is needed with low-yielding fields and greater seeding rates are needed with high-yielding fields. The problem is knowing how much the field will yield.

As always, contact me for more details regarding these tips or discuss other early-season soybean issues.

New tool for Soybean Variety Trial Data

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David Holshouser, Virginia Tech Extension Soybean Agronomist & Virginia Sykes, University of Tennessee Extension Variety Testing & Agroecology

Which soybean variety is best suited to my region? State variety testing programs provide critical research to help answer that question by evaluating hundreds of soybean varieties every year across multiple locations within a state. But what if we think beyond the bounds of our state borders when it comes to variety evaluation?

While a single state alone provides valuable data, our growing regions often cross state lines. A location in southeastern Virginia may share more similarities to sites in eastern North Carolina than it does to the Northern Piedmont of Virginia. Furthermore, by combining variety testing data across multiple states, we can create a more robust dataset that allows us to better predict which varieties are best suited to specific regions and growing conditions.

Pulling and combining data from select locations within multiple state variety testing programs can be a daunting task. Over the past year, a team of variety testing coordinators from Tennessee, Arkansas, Kentucky, North Carolina, and Virginia have been working to make that process a lot easier. Through funding from the United Soybean Board and in collaboration with Centrec Consulting Group, LLC, we created a tool that will allow users of variety test data to combine and visualize soybean variety testing data across multiple states in the Mid-South. This new tool is available at https://marketviewdb.centrec.com/?bi=MidSouthVarietyTrials.

In addition to choosing locations, another key component of this database is the ability to filter the results to include only the relative maturities, brands, and herbicide tolerances that you want. It can also let you chose whether to include irrigated and/or non-irrigated, or full-season and/or double-crop sites.  You can also chose the soil textures that you are interested in.

I won’t go into the details of how to use the site in this blog.  But, try it out.  Contact me with questions or comments.

The database currently contains 2018 – 2020 data but will be updated as 2021 soybean variety trial data becomes available. We hope that you find this tool useful. We would value your feedback/suggestions as we continue to refine this product to better meet stakeholder needs. A brief survey can be found at https://utk.co1.qualtrics.com/jfe/form/SV_6u5lHEwEOXnXODA.

The database described in this article was developed with support from the United Soybean Board.

Introducing the New & Improved Soybean Yield Contest

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In an effort to better recognize Virginia’s soybean producers, Virginia Soybean Association is completely revamping the 2021 Soybean Yield Contest! Through a combination of checkoff dollars and sponsorship support, we’re happy to announce the  a new and improved soybean yield contest.

There will be two categories: full-season and double-crop. There is no restrictions on irrigation (irrigated fields are accepted). Most of all the awards for the top 3 winners in each category has increased substantially due to our sponsors (see below).

1st Place – $2,500

2nd Place – $1,000

3rd Place – $500

This has already garnered a lot of interest. We look forward to receiving your entries.

For more information and entry forms, visit the Virginia Soybean Association website or contact me.

Do I plant soybean or wait for rain?

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Until these big high-pressure systems sitting in the eastern part of the country move east, it looks as if we are in for another week or so of dry weather. This is not good for soybean planting, any way you look at it.  So, what should we do?

There are basically three options:

Plant shallow in dry soil and hope for enough rain to get the seed out of the ground. If you decide to take this approach, you want to ensure you achieve uniform seed depth and that you are not allowing the seed access to moisture below the seed that could lead to variable emergence. This approach would be less risky in clean-tilled situation where you are more confident that you have dried the soil out at shallow depths. Soybean seed will sit in the ground for several weeks and still emerge well when rainfall occurs. Some worry about “cooking” the seed during this period.  Although it is true that the seed will continue to respire and its ability to germinate will decline, the bigger risk is that you catch a small rain that allows the soybean seed to imbibe water but not enough to get it out of the ground.

Caution must be exercised in no-till systems.  With no-till the soil has not been uniformly dried out with tillage; therefore, there is non-uniform moisture distribution across the field.  This leads to uneven access to moisture and ultimately emergence variability. Parts of the field will have adequate moisture to get the soybeans out of the ground, other parts will be completely dry as in tilled conditions, and much of the field will be in between.  Those in-between areas are likely to have enough moisture to swell the seed and/or initiate germination but not have enough moisture to allow the seedling to emerge.  This is my least favorite option.

Plant deep to the moisture. Under most conditions, soybeans may be planted 0.75 to 1.5 inches deep. But I don’t usually like to go much over 1 inch deep, especially in May.  I want soybean to come out of the ground as fast as possible. With that said, we planted some at 1.5 inches last week. Soil temperatures are generally high enough right now for the seed to germinate and plants emerge relatively quickly. Soybeans should not be planted deeper than 2 inches. Many are not finding soil moisture at less than 2 inches. Even if there is moisture 1.5 inches down, exercise caution using this approach, especially your soils are prone to crusting, because a heavy rainfall could seal the soil before the soybeans emerge. In tilled conditions, the planter can push the soil down a little, creating a ridge of fluffy soil on each side.  A heavy rain will cause this soil to move into that furrow and possibly add another ½ to 1 inches of soil to your depth.  If you are going to go this route, check the emergence score on the variety.

Keep the seed in the bag until the next time we catch rain. This is the safest approach and the one that I am leaning to now. Based on historical data, we have another couple of weeks before we start seeing yield declines from delayed planting. Data from recent research throughout the Mid-Atlantic shows that each day delay in planting past mid-June can result in a ½ bu/A or more yield loss and in general these yield declines begin in the second or third week of June. We still have some time before we get to that point. The optimum planting date range for soybeans is late-April through mid-June, although it will vary from year-to-year and field-to-field based on rainfall, soil water holding capacity, and soybean maturity, but the goal is to get the soybean plants to lap the middles before reproductive growth begins. We still have still have time to do this in most cases. 

Waiting to plant is more of a concern for those who still have early-maturing varieties to plant (MG 3 and early-4), as these varieties will have less time for vegetative growth. I do suggest planting your earliest maturity groups first, whichever strategy you choose to employ.  Later maturity groups have more time for adequate growth when planting is delayed.

What about fungicide seed treatments? You have likely already decided on this and cannot change.  But fungicidal seed treatments are less likely needed in this situation where soils are warm. It looks as if temperatures will be warming all week, so I don’t see cold soils as a problem.

Whatever decision a grower makes, uniform seed placement in critical to achieve uniform emergence and ensure each seed has as equal of access to water as possible. I don’t get too concerned if some plants emerge just a few days apart, but we don’t need them emerging a week apart. Dr. Rachel Vann of N.C. State discussed the importance of uneven and delayed emergence in soybeans – How Important Is Uniform Emergence in Soybeans?  Still, keep in mind that although earlier emerging plants will usually yield more, the late emerging plant will still contribute to yield.  Due to soybean’s compensatory ability, the yield on the whole will differ little from only a few days difference in soybean emergence within the row.  If you know me, you know that I’m not a fan of planting with drills due to lack of equal spacing within the row.  This lack of even spacing will become increasingly important if plant emergence is not good. 

In conclusion, there are advantages and disadvantages to each planting option discussed, but we still have time to plant soybeans in our region before we see drastic yield declines. All options discussed will likely result in delayed emergence due to environmental conditions.

Estimating Soybean Yields

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Although it’s hard to accurately estimate soybean yields until maturity, doing so can give you an idea of your crops potential this year or differences between fields or soil  types.  Maybe you’re considering entering the soybean yield contest or maybe you just want some peace of mind.

Here are some general guidelines for estimating soybean yield.  Again, estimating soybean yield is inaccurate unless detailed sampling is done late in the growing season.  Estimates are usually not very good until the soybean approaches physiological maturity (R7).  Only about 50% of the total seed dry matter has accumulated by the R6 development stage.  Stresses during the R6 to R6.5 stages can result in large yield losses mostly by reduced seed size, but also by reduced pods or beans per pod.  After R6.5, stresses will cause a much smaller loss. 

To estimate yields, follow the steps below.  Be sure to sample in 5 to 7 different areas of the field.

1. Determine the number of row feet needed to make 1/1000th of an acre from the table below.  In narrow rows, one may use 3 or 4 side-by-side rows instead of one long row

2. Determine the plant population per acre.  Count the number of plants for the row feet determined above in 5 to 10 randomly chosen area of the field.  Multiply this number by 1000.  Average the number of sampling areas.  Note that the more areas of the field that you sample, the more accurate are your estimates.

3. Determine the number of pods per plant.  As you are making your stand counts, pull up 5 consecutive plants in the row you counting.  These 5 plants should be growing next to each other.  This will insure that you don’t just pull the best looking plants in the row.  Also, try to avoid gaps in the row as the plant next to the gap will have more pods than the average plant. Count the number of pods on these plants within the sample area and average.

4. Determine the pods per acre.  Multiply the plant population (step 2) by the pod average (step 3).

5. Determine the number of seeds per acre.  Multiply the number of pods (step 4) by 2.5 seed per pod.  This is an average number of seed per pod for most varieties.  Some varieties may have more, some less.

6. Determine pounds of seed per acre.  Divide the seeds per acre (step 5) by 3000 seeds per pound.  This number can vary from 2500 to 3500.  Higher numbers represent smaller seed that are more likely during late-season drought.  Smaller numbers represent seed that form with abundant August/September rainfall.  You may want to obtain a low, medium, and high estimate.

7. Determine the yield estimate.  Divide the pounds per acre (step 6) by 60 pounds per bushel.

As an alternative to calculating your numbers, you can use the chart below to determine how many pods or seed per pod you would need at three different plant populations to obtain a certain yield.

2020 Virginia Soybean Yield Contest

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Each year, the Virginia Soybean Association in cooperation with Virginia Cooperative Extension sponsors a soybean yield contest.

The purpose of the Virginia Soybean Yield Contest is to emphasize and demonstrate the practices necessary to produce maximum economic yields, to recognize those producers who grow high-yielding soybeans, and to gather data on the practices utilized by these outstanding producers.

There are three Soybean Yield Contest categories: 1) Full-Season, Non-irrigated; 2) Double-Crop, Non-irrigated; and 3) Irrigated (Full-Season or Double-Crop). 

Any grower (owner-operator, tenant, or tenant-landlord team) who is a member of the Virginia Soybean Association and produces 10 acres or more of soybeans within Virginia’s boundaries is eligible.  Participants may enter one, two, or all contests. 

Details of the contest can be found at the Soybean Extension & Research webpage. Please contact your local Virginia Cooperative Extension office if you wish to enter the contest, preferably at least 5 days before harvest. 

Virginia Ag Expo Canceled to COVID-19 Concerns

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The 2020 VA Ag Expo has been cancelled. The Ag Expo committee with guidance from the Virginia Soybean Association and Virginia Grain Growers Association have made this difficult decision to ensure the health and safety of exhibitors and guests as a result of the COVID-19 pandemic. We will be reaching out to each exhibitor and sponsor to discuss our next steps. We appreciate your support and look forward to 2021!