Workhorses, Racehorses, and Quarter horses

Today is the first day in 2 weeks that we’ve been able to harvest due to weather and a combine breakdown.  So, we are not that much farther along in getting variety test data to you than we were last week.  However, I hope to get out some preliminary data by Thanksgiving.

Last week, I indicated that certain relative maturities do better in some parts of Virginia than others.  This week, I I’ll get a little more specific and discuss choosing the best variety for a given yield potential.

First and foremost, I will continue to emphasize that variety selection should be based on multi-year multi-site data.  Basing your selection on a single test (maybe closest to you) and single year is a recipe for failure.  However, I don’t necessarily recommend always choosing a variety based on average yields over site-years – although a very good place to start.  This may seem a little contradictory, but let me explain.

Certain varieties do better under high-yielding environments.  I like to call these “racehorse” varieties.  Choose such a variety if you want to win a yield contest.  Other varieties may yield more than others under stressful conditions.  I refer to these as “workhorses”.  And there are some that tend to do well, regardless of the yield potential – I’ll call these “quarter horses” (quarter horses can run very fast for short distances and you can still ride them long distances over quite rugged terrain).

Last year, we analyzed 5 years of variety test data and classified all varieties that we tested as one of the above.  Examples of our results are shown below. The graphs represent the yield of a single variety versus the yield of all varieties tested at that site and year.  Each symbol represents a different site-year.

To summarize, the vast majority of varieties are neither racehorses or workhorses; they perform equally in all yield environments.  So, averages will work just fine in most cases.  But, if you know you have a great- or poor yielding soil or if you are irrigating, then you may want to look into those varieties that fit that situation.

We have all of these data in an excel spreadsheet.  If interested, let me know; I’ll be happy to share upon request.

What’s the Best Soybean Maturity Group for your Farm

Yields are coming in from our variety tests – yields are good, not great, but good, ranging from the upper 40’s to low 70’s.  I hope to get a summary of the maturity group (MG) 3 and 4 tests out soon.  Be looking for them.

In the meantime, a questions that continues to arise if “What is the best maturity group for my farm?”  Or “What’s the best maturity group for my field?”  This is a very valid question.  Some years MG 4’s will shine and other years the MG 5’s are best.  Occasionally, MG 3 or 6 look good (the 6’s have been performing very well lately – as long as the frost holds off until mid-Nov!

An attempt was recently made (and published) to redrawn the MG lines in the U.S (Mourtzinis and Conley, 2017) – see the map to the upper right.  The researchers used variety test data from nearly all states to come up with the map shown.  While this map is more-or-less accurate when looking at the U.S. as a whole, it is not when you look closer (i.e., at individual states).

To better answer your questions regarding MG’s in Virginia, we took 10 years of our variety test data (around 15,000 plots) and began evaluating the probability of:

  1. a relative maturity (RM) yielding at least as high as the other RM’s tested at that location
  2. a RM yielding significantly higher than the other RM’s tested at that location.

Results are shown in the following graphs. Note that we split the results into full-season and double-crop soybean.  We have also divided each MG into early-, mid-, and late-RM’s.  The total bar height answers question 1 – the probability that the RM does at least as well at the others.  For instance, as expected, there is an 80 to 100% probability that MG 5’s will yield at least as much as other relative maturities in Blackstone (Southern Piedmont, droughty clay soils).

The hatched part of the bars answer question 2 – the probability that the RM yields significantly more that the other RM’s.  Using the Blackstone example, the 5’s yield significantly more than other MG’s 30 to 60% of the time.

Of course the “devil is in the details”.  There are soil properties and environmental conditions that control which RM is best in a given year.  If interested, contact me; I’ll give you my preliminary thoughts on that.  Rainfall is definitely the biggest influence – not how much we receive but when it falls; but that is random in Virginia.  There are other issues.


To summarize:

  • MG 3’s and 4’s are best suited for the most northern and western location (Orange).
  • MG 5’s perform best in our most southerly locations (Blackstone and Suffolk).  But, the late 4’s can make a strong showing in some years, especially at Suffolk (I think I know why; its not just when the rain fell. Contact me.)
  • Both MG 4’s and 5’s perform well at Warsaw (we can’t explain the full-season late-4 results, yet).  Note that yield potential of the later 5’s decline with double-crop plantings at this northerly, but Coastal Plain site (probably frost damage).
  • All MG 4’s (early, mid, and late) perform best when planted in May at our Eastern Shore location (Painter).  There are curious things happening here (while not that far south, its our most easterly and probably the most consistently favorable environment for growing soybean).  Note that early- and mid-4’s are no better than 5’s when planted double-crop.

1st Attempt at a Relative Maturity Map in Virginia

I’ve made an attempt at drawing a Virginia map.  But do not read too much into this!  This is based only on 5 locations (although 10 site-years and thousands of plots at each location) and the “devils in the detail”.  An I did not use GIS to draw this map (the lines are not 100% accurately located).

Do not assume that I want you to plant only these RM in these areas, only that these tend to do best in most years.

How do you use these data?  Make most of your chosen varieties fit these results.  However, allocate a smaller acreage to those RM’s that can occasionally break records.

On a closing note, these data also indicate that early RM’s do better on our best, most productive land.  But, that’s a topic for next week.

Update on the Boxwood Blight Situation in Virginia and Recommendations for Minimizing Disease Introduction and Spread from the Virginia Boxwood Blight Task Force

Current situation in Virginia, 10/6/17

According to records of the Virginia Boxwood Blight Task Force, to date boxwood blight has been diagnosed in over 70 locations and approximately 30 counties in Virginia. There are likely additional undocumented incidences of the disease, for example, if no sample was submitted for diagnosis through Virginia Cooperative Extension or the Virginia Department of Agriculture and Consumer Services.

Although boxwood blight has been diagnosed in many counties in Virginia, there is no indication that it is widespread throughout any Virginia county. This is not unexpected, based on the current understanding of the biology of the boxwood blight pathogen. Boxwood blight is typically initially introduced into a new location on infected boxwood or other susceptible plants (e.g. pachysandra and sweet box). Holiday greenery containing infected boxwood can also introduce the disease into a new location. However, boxwood blight is not spread long-distance via wind currents. Therefore, one need not panic even if the disease has been found in one’s county. However, if the disease has been identified in one’s neighborhood, then there is a heightened risk of local spread of the disease.

After the initial introduction of boxwood blight-infected boxwood (or pachysandra or sweet box) into a location, neighborhood boxwood plantings are at risk for boxwood blight. There are a number of means by which the sticky spores of the fungal pathogen can move through a neighborhood. For example, they can be spread via contaminated pruning tools, spray hoses, equipment, vehicles, clothing, shoes, or infested leaves spread by leaf blowers. Wildlife (including birds), insects, domestic animals or humans that have been in contact with the spores may also move the infective spores through a neighborhood. Movement of the pathogen by many of these means has been documented in locations in Virginia.

To safeguard Virginia boxwood plantings and production, we call for community awareness and efforts to avoid accidental introduction of boxwood blight into new locations and prevent local spread of boxwood blight:

Specifically, we recommend and stress the following:

  • Purchase boxwood, pachysandra and sweet box only from a nursery that is listed as a member of the Boxwood Blight Cleanliness Programand/or from a retailer who sells only boxwood produced by nurseries in the Boxwood Blight Cleanliness Program.
  • If boxwood blight is suspected, immediately contact your local Extension office, which can submit a sample for confirmatory diagnosis. Where boxwood blight is confirmed, it is strongly recommended to immediately remove and double bag all diseased plants and fallen leaves as well as contaminated soil underneath the planting. The bagged waste should be removed to a designated landfill to mitigate disease spread to other boxwood in the landscape and other properties nearby.
  • Employ only landscape professionals who are aware of how boxwood blight spreads, since boxwood blight can be introduced to properties through landscape maintenance activities. The fungal spores and fallen diseased leaves can be moved on tools, boots, tarps, hoses, clothing and vehicles. Landscape professionals should have a stringent sanitation plan in place to decontaminate tools, equipment, vehicles, clothing, shoes, etc. between landscape locations and other practices that minimize the chance to move the disease through landscaping activities.
  • Adhere to best management practices outlined for boxwood blight, which are detailed in PDFs available at the Virginia Boxwood Blight Task Force website.

Additional Precautions for Landscape Professionals:

  • Landscape professionals are strongly advised to walk through a site before beginning work. This is to identify any potential boxwood blight problems and/or risks. We have heard anecdotal reports from landscape professionals of both serious equipment contamination issues and spread of the disease by unexpected encounters of the disease in a landscape.
  • Landscape contractors should at all times be equipped with a sanitation “kit” for disinfesting tools and equipment and take precautions to avoid moving spores on clothing, boots, hoses, vehicles, etc. Specific recommendations for effective sanitation methods are detailed on the Virginia Boxwood Blight Task Force website (under the “Sanitizers” tab).
  • Landscape companies should ensure their staff are familiar with the symptoms of boxwood blight so that they can recognize the disease in the landscape. Laminated wallet cards with images of symptoms of boxwood blight and information on the Virginia Boxwood Blight Task Force website are available through your local Virginia Cooperative Extension

Resources: the Virginia Boxwood Blight Task Force website and Best Management Practices

Refer to the Virginia Boxwood Blight Task Force website for further information on boxwood blight. We recommend that you familiarize yourself with the appropriate Best Management Practice (BMP) for your situation. The BMPs are available on the website as PDFs.

Black light trap report for Sep. 28, 2017

Average nightly black light trap catches of corn earworm moths this week were: Southampton=0.3; Prince George (Templeton)=6; Prince George (Disputanta)=4; Hanover=2; Suffolk=26. Here is the data table: BLT_28_Sep_2017

Most traps are being stowed now. We greatly appreciate the reports this season from Watson Lawrence (Chesapeake); Mike Parrish and Angela Duncan (Dinwiddie); Laura Maxey-Nay (Hanover); Scott Reiter (Prince George); Mary Beahm (Warsaw); LIvvy Preisser (Southampton); and Sally Taylor and her entomology team (Suffolk). We also want to thank the growers who hosted the traps on their farms.

Distribution of Herbicide-Resistant Italian Ryegrass in Eastern Virginia

Charlie Cahoon, Extension Weed Specialist

Eastern Shore AREC-Virginia Tech

Italian ryegrass is one of the most common and troublesome weeds Virginia small grain producers face.  The weed competes with wheat for essential nutrients, sunlight, and moisture and also interferes with harvest.  In the past, growers have relied upon herbicides, such as Axial XL, Hoelon, PowerFlex, and Osprey, for control of Italian ryegrass.  However, herbicide resistant Italian ryegrass biotypes have developed, limiting the herbicide options available to growers.

During the summer of 2016, the weed group at the Eastern Shore AREC traveled Eastern Virginia in search of resistant Italian ryegrass.  To broaden the survey, we solicited samples from extension agents and members of the agriculture industry.  In total, 82 samples were collected throughout Eastern Virginia (Image 1).  The objective of this survey (and subsequent resistance screening) was to determine the distribution of resistant biotypes in Virginia; allowing growers to tailor management strategies specific to biotypes in their area.

Italian ryegrass heads collected during the summer were allowed to dry down and then threshed to separate the seed.  Approximately 400 seed from each population were planted in a seed tray.  Once Italian ryegrass reached 3.5 to 4 inches in height (1 to 2 leaf), plants were treated with a 1X rate of Axial XL (16.4 oz/A), Hoelon (43 oz/A), PowerFlex HL (2 oz/A), and Osprey (4.75 oz/A). A non-treated check from each sample location was included for comparison purposes.  Visual injury was recorded at 28 days after treatment (DAT) for Italian ryegrass treated with Axial XL and Hoelon.  PowerFlex HL and Osprey are both ALS-inhibiting herbicides and act much slower than the ACCase-inhibiting herbicides (Axial XL and Hoelon).  Therefore, ryegrass treated with these products were evaluated 42 DAT.  Also at 42 DAT, Italian ryegrass biomass (and subsequent % biomass reduction) was determined by cutting and weighing the above ground portion of ryegrass.

Image 1. Locations of 2016 Italian ryegrass samples collected.

Overall, approximately 23% of all samples collected were resistant to Axial XL (Image 2) compared to 30% that were resistant to Hoelon (data not shown).  Most samples resistant to Hoelon were also resistant to Axial XL.  However, for 6 samples, Axial XL remained effective despite poor Hoelon activity.  Axial-resistant Italian ryegrass is widespread in two of Virginia’s major wheat producing regions (Eastern Shore and southern Chesapeake/Virginia Beach).  Of the 14 samples collected in Northampton Co., 9 were found to be resistant to Axial XL (64%).  In contrast, none of the 5 samples collected from Accomack Co. were Axial-resistant.  In southern Virginia Beach and Chesapeake, 5 of 6 samples collected were resistant to Axial (83% of samples).  Excluding the Eastern Shore and southern Chesapeake/Virginia Beach, only 9% of remaining samples were resistant to Axial XL; 1 samples east of Stony Creek in Sussex Co.; 1 sample south of Waterview in Middlesex Co.; 1 sample northeast of Newtown in King and Queen Co.; 1 sample northwest of Loretto in Essex Co.; and 1 sample south of Somers in Lancaster Co.

Image 2. Distribution of Axial-resistant Italian ryegrass in Virginia.

ALS-resistant Italian ryegrass is more widespread throughout eastern Virginia.  Of the surveyed populations, 92 and 93% were resistant to Osprey and PowerFlex HL, respectively.  Producers should keep in mind the presence of herbicide-resistant Italian ryegrass nearby does not automatically mean they have a resistant biotype on their farm.  Fields with escaped Italian ryegrass were purposely chosen for this survey.  It is best to rely on field history and performance of herbicides in the past when making management decisions.  However, it is always a good idea to rotate modes of action to delay the development of resistant biotypes.

Unfortunately, if ryegrass is resistant to Axial XL and the ALS-inhibiting herbicides (Osprey and PowerFlex HL), there are no postemergence options left.  In this situation, a residual product that includes pyroxasulfone (Anthem Flex and Zidua) is suggested delayed-preemergence or early postemergence.  These products offer residual control of ryegrass only (they will NOT control emerged ryegrass).  It is imperative that these products are applied and activated by a timely rainfall prior to ryegrass emergence.  Rotating away from wheat also presents an opportunity to control Italian ryegrass (and prevent seed production) with glyphosate early burndown prior to planting corn or full-season soybean.  Be aware that glyphosate-resistant Italian ryegrass is suspected in northeast North Carolina and eastern Virginia.  In this situation, paraquat plus a residual herbicide like s-metolachlor applied to fallow ground during the fall would be in order.

Image 3. Axial XL-susceptible Italian ryegrass collected near Nassawadox, VA treated with no herbicide (left), Axial XL at 16.4 fl oz/acre (middle), and Hoelon at 43 fl oz/acre (right).

Image 4. Axial XL-resistant Italian ryegrass collected near Cheriton, VA treated with no herbicide (left), Axial XL at 16.4 fl oz/acre (middle), and Hoelon at 43 fl oz/acre (right).



Eastern Shore AREC Field Day CANCELED!

Due to impending rain Tuesday and Wednesday and already saturated soils, the Eastern Shore AREC field day scheduled for Wednesday, September 13, 2017 has been canceled. Let’s hope Hurricane Irma keeps tracking further west. We certainly do not need any more rain!

Estimating Soybean Yield

This is the time of year when many are wondering what kind of yield potential is out there.  You can estimate your yield using the steps outlined below.  But I will warn you that such an estimate is not very accurate until soybean reach the late-R6 or R7 stage.  In my experience, when trying to estimate yields during the late-R5 or early-R6 stages, cut the estimate in half – believe it or not, that usually works!

My point is to use extreme caution.  Never make additional sales based on these “estimates”.  But, such an estimate is useful if you’re thinking about entering a yield contest or just to help ease some worries (or maybe cause more).

To estimate soybean yield:

  1. Calculate the number of pod-bearing plants per acre.  Use the 1/100th of an acre method: Count the number of plants per 70 foot of row (7.5-inch spacing), 35 foot per row (15-inch spacing), or 17.5 foot per row (30-inch spacing) – You can adjust this for other row spacings; then multiply by 1000.  Do this in 5 to 10 locations per field, depending on field size or area of interest.
  2. Estimate the number of pods per plant.  Some say to collect 10 random plants.  I don’t particularly like this method because we tend to select the best plants and overlook the weaker ones with few pods.  I suggest taking 10 plants in a row from the same locations you sampled for plant population.  Divide the number by 10 to get pods per plant.
  3. Estimate the number of seed per pod.  This gets a little more difficult.  You can choose a number from visually observations or you can just use 2, 2.5, or 3 seed per pod to get a range.  If the seed are mature, you can shell and count all pods from several plants at each  sampling location (just remember how many pods you shelled).
  4. Estimate the number of seed per pound.  3,000 seed per pound is about average, but it can range from 3,500 to 2,500 per pound.  Also, be careful with varieties that commonly contain 3 seed pods; the seed of these varieties will almost always be smaller.  Another way to do this is to weigh the seed that you shelled from step 3 – be careful, you need to account for seed moisture and if the seed are not yet mature, they may have not stopped filling.

Use the numbers above to calculate yield using the equation below:

Bushels per Acre  = [(plants/1,000th acre) x (pods/plant) x (seeds/pod)] ÷ (seeds/pound) ÷ (60 pounds/bushel)

The easiest mistake to make is in steps 3 and 4.  I suggest using a range of seed per pod and seeds/pound.  With experience, you’ll get pretty good with yield estimates.

Insect update for Sep. 7, 2017

Most reporting black light trap stations this week had decreased corn earworm moth captures (except for Chesapeake remaining constant). Nightly averages were Chesapeake = 11; Southampton = 1; Suffolk = 8; and Warsaw = 4 moths. Here is the data table:  BLT_7_Sep_2017

No brown marmorated stink bugs were caught this week in the black light traps.