Corn Rootworms in Central Texas

(Note: I’m an agronomist working across the fruited plains of Oklahoma and down through north, central and south Texas. This blog is specific to that geography.)

Corn, specifically continuous corn (monoculture), is predominantly found throughout central Texas. These acres can host two major corn rootworm species: Mexican Corn Rootworms and Southern Corn Rootworms. Other areas tend to have more crops in rotation – sorghum and cotton to the south and pasture and alfalfa to the north – and have fewer incidents of crop damage from rootworms. Yes, wheat is grown throughout the region and can break the lifecycle if taken to grain but likely not if planted back to corn after being cut for wheatlage/silage (which is done primarily in the dairy-concentrated area around Stephenville, TX.)

The main rootworm specie that causes the most damage is the Mexican Corn Rootworm (MCRW). Without adequate control, it can cause significant economic damage nearly every year that corn is grown continuously. Yield damage can be as much as 40 bu/a or more and is manifested in lodged, stressed plants and reduced ear size. Fortunately for growers, insecticidal Bt traits control this pest. In the absence of traits, planter-based insecticide applications and some seed treatments can provide control, albeit sometimes limited under high pest pressure. Growers can easily scout for adult beetles around pollination time and assess potential damage for the following year’s crop. (I know, I know, it’s hot that time of year and nobody wants to be in corn field when it’s over 100 degrees. Trust me on this, it’s worth it!)

The other rootworm specie that can cause damage is the Southern Corn Rootworm (SCRW). While the MCRW can be an annual pest, SCRW might be a problem one in only seven or eight years. Unlike the MCRW, outbreaks can not be predicted since it has so many hosts and overwinters as an adult rather than as larvae. The thing to remember about SCRW is that no commercially available Bt traits in 2020 have any effect on them. The primary form of control is insecticidal seed treatments.

Unfortunately, having a name in common with the other rootworm species makes it easy to think that plant-based Bt traits should control the SCRW but it is an exception that can be an absolute thorn in a grower’s side. It can be expensive to add seed treatments. Sure enough, the year the grower decides not to spend the money on controlling SCRW, there’s an outbreak and replant is needed in several fields, resulting in added expense and potentially reduced yields. UGH!

There are several websites, extension publications, seed industry articles, etc. on these pests. Should you like more information or have other questions, don’t hesitate to holler at me at peter.hill@pioneer.com.

I want you to do well. ~ph

Please Focus!

After six years and 5,000+ followers on Twitter (of which one-fourth were women and bots who mistakenly thought agronomists were wealthy), and a change in job responsibilities, I decided it was time to refocus my energies on social media. Frankly, I wanted to separate personal life from work and give others an opportunity to step up and take the lead on providing agronomic expertise for the growers. Too, as followers grew, I found myself spending entirely too much time muting and blocking folks that were basically trolling, getting threads completely off target and otherwise wasting my time. So I shut down my main Twitter account (@texasagronomo), set up a new one for my woodworking hobby (@tejaswoodworker) and set about refocusing my role on social media platforms.


A fresh account and a fresh focus on Pioneer Hi-Bred and agronomy.

So we start anew with @Pioneeragronomo in a new job role – that as Product Agronomist covering from Oklahoma to the Rio Grande Valley. This account will continue to support Pioneer Hi-Bred (@PioneerSeeds) and Corteva AgriScience (@CortevaUS) and will focus only on agronomy. Nothing else. And, based on previous experience, I will be quicker to mute or block the drama queens and non-believers in Pioneer genetics and won’t bat an eye or lose a second of sleep in doing so.

I want you to do well. ~ph

2019 Central & South Texas Agronomy Review

Peter Hill, Ph.D. and Adam Owens, M.S

Every year in central and south Texas, nearly 50 Pioneer® sales reps work with growers to plant and harvest over 125 corn and sorghum plots.  All of this takes place in a large region ranging from north of Waco down to the Rio Grande Valley.

In this summary, 2019 performance data of Pioneer® brand corn and sorghum hybrids are highlighted as well as research data on planting populations.  Corn rootworm hybrid performance is also highlighted as 2019 saw extremely high pressure in central Texas.

2019 started with a full soil moisture profile for the entire area.  Late winter rains delayed planting and field work except for a few areas in central Texas which managed to plant “early.”  Central Texas received excess rains throughout the first half of the growing season causing issues with nitrogen loss.  Heat unit accumulation was nearly ideal for the entire area up to the middle part of grain fill – then it turned off hot and dry.  By this time, the yield potential was basically locked in.  Overall, grain quality was some of the best seen in recent years.

Yields were well above normal for some areas in central Texas with others below normal owing to too much rain.  Further south, in the San Antonio area as well as the lower Gulf Coast, yields were outstanding.  Several farmers reported record level yields for both corn and sorghum in these areas. 

Wet years bring out the best in most hybrids but consistency across years and across acres is a challenging concept for the seed industry.  As always, planting a mix of products usually results in the least amount of risk across the farm.

As you study the findings in this summary don’t be afraid to reach out to your local Pioneer or Corteva sales rep with questions or comments.   Now, read on!

CORN – GENETICS

The tale of two years – 2018 and 2019.  Last year was a severe drought for most areas while 2019 was wetter and nearly ideal.  Unfortunately, hybrids that do well during a drought are not always the best when it rains.  Below are the Pioneer® brand hybrids with the most top three finishes for the last two years, ranked in order.

Other hybrids are available but this table shows why planting a mix of hybrids (by agronomics and yield potential as well as maturity) is important for controlling risk across the farm.  Take Pioneer® hybrid P1847VYHR (RM 118), for example.  Brand new in 2018, it was considered “average,” as were most full maturity hybrids.  This was because soil moisture ran out early and nearly all full season hybrids were below average (P2089VYHR a notable exception).  Yet, in 2019 it was one of the strongest performers.  Pioneer hybrid P1395YHR, a perennial favorite, fell down the charts as hybrids with higher top-end yield potential rose to the top.

Summary:  It’s easy to fall in love with the new releases from seed companies.  We always encourage customers to never plant more than 20% of their acreage to new products.  Spread the risk of product failure by mixing up hybrids and consider spreading out maturity to help manage harvest and mitigate timing of environmental stress.  Maturities with various traits are available from 103 CRM to 120 CRM. 

CORN – MEXICAN CORN ROOTWORM

Central Texas is home to a variant of the Western Corn Rootworm, called the Mexican Corn Rootworm (MCRW).  While it is found only in central Texas, it’s behavior is identical to that of the Western.   There is only one generation per year; adults emerge before or during silking, mate and then move down into the soil to lay eggs.  The eggs overwinter, larvae hatch after enough heat has accumulated and then feed on corn roots.  They develop into adults and continue the cycle.  MCRW is mostly an issue with continuous corn rotations. 

Do not confuse this specie with the Southern Corn Rootworm (SCR).  MCRW has one host only – corn.  SCR has over 100 hosts and overwinters as adults, not as larvae or eggs.  SCR can infest corn in any rotation and is best controlled with seed treatments.  Note that corn rootworm traits expressed in the plant HAVE NO EFFECT on SCR.               

Below is a drone image of a test plot near McGregor, TX.  The strips that appear down are lodged due to MCRW root feeding.  The strips that appear normal contain corn rootworm traits.

Summary:  Infestations of MCRW can SIGNIFICANTLY reduce yields and impact fields with as few as three years of continuous corn.  Scout fields before, during and after silking to evaluate adult beetle population.  Treatment thresholds are published and control can be effective.  Traits are not effective on SCR. 

TECHNOLOGY SPOTLIGHT – BLUETOOTH & GRAIN CARTS

Occasionally, a technology comes along that inspires confidence in conducting on-farm research while also serving a practical purpose for the farming operation.  What caught our eye this year was the Libra Cart Bluetooth technology by Agrimatics.  Grain carts are outfitted with unloading sensors and when coupled with Bluetooth allow the operator to see and record weights on smart devise.  For conducting on-farm research, you don’t need to stop and get out of the combine and grain samples can be taken just outside the cab door.

This system is a pragmatic alternative to GPS driven data management systems such as yield monitors coupled with computer programs.  From an on-farm research standpoint, ease of communication and real-time recording of weights make conducting large strip trials much easier to execute.  One feature is the recording of weights when unloading commences – you’ll never miss a weight that you forgot to write down!

(Source:  Agrimatics.com.  Please note, neither Pioneer nor Corteva AgriScience sells or promotes this technology.)

TECHNOLOGY SPOTLIGHT – DRONES

Pioneer maintains one of the largest drone fleets in the US.  Nearly every field and product agronomist uses a drone in day-to-day work during the growing season.  Proprietary software is used for taking stand counts and collaborations with DroneDeploy allowed for in-season plant health assessments.

Using drones in production agriculture complements other tools such as satellite imagery and in-field scouting.  The following are a couple of examples of how Pioneer agronomists used drones. The first is aDroneDeploy image showing degrees of crop stress using software that allows the grower to see a “live” map soon after flying. The second image shows an 80-acre field where 16 stand counts were taken in less than 20 minutes. Note the color designations that show deviations from what the grower planted.

DroneDeploy image showing degrees of crop stress.
Stand count for a large field, completed in less than 20 minutes.

PLACING HYBRIDS – RIGHT PRODUCT, RIGHT ACRE

In the seed business, rarely can you find one hybrid that does it all – performing best in drought; when it rains; and on every soil type.  Over 100 plots are planted every year in central and south Texas.  This helps Pioneer professionals to better understand product behavior and how to position them on your farm.  Here are the key factors that affect product performance and are key to understanding what might work on your ground:

  • Historic yield level
    • Dryland sub 80 bu/A
    • Dryland 80-100 bu/A
    • Dryland 100-140 bu/A
    • Irrigated
    • Other
  • Soil texture/drainage/terraces
  • Crop management
    • Fertility
    • Population/Row Spacing
    • Fungicide
    • Tillage
    • Crop rotation

While certain hybrids are widely adapted, most are not.  There are some that don’t like “wet feet.”  There are some that can’t tolerate foliar disease or high winds (brittle/green snap).  In fact, as noted in earlier sections, some don’t perform well when planted at high populations.  Make sure your Pioneer rep understands the “lay of your land” and reference the category chart that follows.