Sorghum Tips

Wet Weather and Nitrogen Losses from Soil

This tip was provided by:

Ronnie Schnell, Cropping Systems – Statewide, College Station, ronschnell@tamu.eduStatewide


Wet Weather and Nitrogen Losses from Soil

Nitrogen losses from soil following fertilizer applications to crops can be difficult to quantify after periods of wet weather. How much nitrogen was lost and how much does it vary spatially? If significant amounts are lost, yield reductions are likely. Answering these questions is critical when considering supplemental or “rescue” applications of nitrogen. Understanding nitrogen loss pathways will help to estimate nitrogen loss.

Nitrogen is lost from soil by four main pathways: denitrification, runoff, leaching and volatilization. When excessive rainfall and saturated soil conditions occur, denitrification and leaching are the greatest concerns. Many factors can affect denitrification and leaching losses, including soil texture, fertilizer type and rate, placement and timing, soil temperatures and the amount of rainfall received (duration of saturation).

Nitrate nitrogen (NO3-N) is required for nitrogen to be lost from soil by these two processes (leaching and denitrification). Understanding how much nitrate-nitrogen is in the soil is the first step to estimating potential losses. Fertilizer products may contain nitrogen in ammonium (NH4) and nitrate (NH3) forms. UAN (32-0-0) has about 25% of the total nitrogen as nitrate. Ammonium forms of nitrogen are rapidly converted (oxidized) to nitrate by soil bacteria in a process known as nitrification. The process is faster with warm soils. Most of the ammonium may be nitrified within several weeks under warm conditions. Nitrification inhibitors can be used to delay this process. Saturated soils (oxygen depleted) will also halt the nitrification process. Therefore, timing and source of nitrogen fertilizer plus the use of nitrification inhibitors will affect how much nitrogen is nitrate form. Nitrogen fertilizer applied several weeks or more before excessive rainfall without nitrification inhibitors is likely largely in nitrate form. This does mean it is lost but has the potential to be lost.

Coarse textured soils (sandy) are much more susceptible to leaching of nitrate below the rooting zone of the crop. Finer textured soils (clay) are susceptible to leaching and denitrification, although leaching potential is substantially lower compared to sandy soils. Low infiltration rates and ponding can result in extended periods of saturation. This will increase the potential for denitrification losses. As soil oxygen is depleted, some soil microbes will switch to nitrate for survival, releasing the nitrogen in gaseous forms that escape into the atmosphere. Some estimates suggest 2 to 5% of the soil nitrate-nitrogen can be lost per day of saturated conditions. The total loss will depend on nitrate available in soil, number of saturated days and temperature. Actual losses can vary widely depending on these factors.

Determining potential nitrogen losses in-season is difficult. Deciding if and what amount of additional nitrogen to apply can be challenging. If you have reason to believe significant nitrogen has been lost, there are several considerations when planning supplemental nitrogen applications. First, ensure that plant stands/populations are adequate for expected yield goals. Next, consider the growth stage of the crop. Applying nitrogen closer to growing point differentiation will improve yield response (see previous tips). However, if panicle initiation has passed but conditions were favorable during this period, significant yield potential may exist yet.  Some yield loss can be expected with later applications (pre flowering) but it is important to capture yield potential that does exist. Finally, consider grain price and nitrogen cost in combination with expected yield response. Applying 100 lbs/acre of urea (46 units of N) will cost about $19/acre ($0.42/ lb of N) plus application cost. With grain at $6.50/cwt, you need about 300 lbs/acre of grain to cover the fertilizer cost. Yield response to N fertilizer under ideal conditions is 100 lbs of grain for every 2 lbs of available nitrogen per acre (over 2,000 lbs of grain per acre in this example). With late applied fertilizer, yield response will likely be lower but may be profitable yet.

If plants have been severely affected by wet conditions, this can result in damaged root systems, reduced or delayed tillering, lower leaf area and reduced yield potential. Response to additional nitrogen is unlikely. Extended periods of stress (saturated soils) at earlier growth stages (3-5 leaf) will have greater impact compared to later growth stages (post flowering). Carefully evaluate the crops recovery once soil conditions improve before considering supplemental nitrogen applications.


Figure 1. Sorghum showing signs of nitrogen stress following excessive rainfall.

2016 AgriLife Extension Entomology Sugarcane Aphid Information

This tip was provided by:

This Sorghum Tip from Extension Entomologist Dr. Ed Bynum, Amarillo, directs sorghum growers in the Texas High Plains to AgriLife Extension entomologist guidelines developed for the region.  These efforts are coordinated by Dr. Bynum, Amarillo, (806) 677-5600,, and Dr. Pat Porter, Lubbock, (806) 746-6101,  in conjunction with the five Extension IPM agents that each cover 2 or 3 counties in the South Plains (based in Lamesa, Brownfield, Levelland, Lubbock, and Plainview)

High Plains

2016 AgriLife Extension Entomology Sugarcane Aphid Information

The March 10 Sorghum Tip summarized sugarcane aphid control recommendations from Dr. Robert Bowling for SCA in South and Central Texas.  In this edition, High Plains sorghum growers are directed to a different set of SCA control recommendations for the High Plains region.  Compared to South & Central Texas guidelines, the initial action thresholds are lower for the Texas High Plains.

 If you have last year’s thresholds on hand in the High Plains, discard them and replace with the information resources below.

Since Dr. Bowling’s update, SCA has been confirmed to have overwintered on Johnsongrass in at least three counties in the High Plains (Dawson, Lubbock, Hale), but IPM agents based in Lamesa & Garden City currently have no reports of SCA on commercial sorghum.

You may access the current statewide AgriLife sugarcane aphid management guide at  In addition to information on SCA identification, scouting, and insecticides, note the High Plains specific information found on pages 4-5.  These High Plains specific guidelines are also published at  (ENTO-047, “2016 Texas High Plains Sugarcane Aphid Management Guide”; you can get laminated cards from your county Extension office or order from )

Overall Texas High Plains AgriLife Extension entomology suggestions for managing SCA follow these six principles:

Primary Options to Reduce Potential SCA Damage on Grain Sorghum 

1)    Plant outside the normal window {Early planting, e.g. late April in the South Plains to reduce risk of infestation in whorl stage, late planting in mid-summer will have a higher risk of infestation in whorl stages, but beneficial insect populations may be increasing.}

2)    Use seed insecticide treatments.  {This might add up to ~$50/bag for seed, but that is still less than $2.50/acre in dryland.  Entomologists have noted that you should anticipate at least 30 days of some protection with any of the insecticide seed treatments.}

3)    Plant “resistant” hybrids (talk to companies).  {All sorghum hybrids are susceptible to SCA at some level, and AgriLife statewide has conducted little research yet on commercial hybrids.  (United Sorghum Checkoff Program has summarized a list of what companies believe is their most tolerant material, see )}

4)    Spray promptly at threshold.  {IPM agent Kerry Siders has noted that a good first shot may eliminate the need for a second spray.}

5)    Re-spray the field as needed.

6)    Preserve biological control—your best friend.Screen Shot 2016-05-27 at 9.10.38 AM


Additional High Plains SCA management tip sections in ENTO-047 include:

  • First Detection:  Is the field at risk?
  • Sampling Decision
  • Control Options after First Application
  • Forage Sorghum Management

For further information on sugarcane aphid in the Texas High Plains and beyond follow the online Texas Sugarcane Aphid News at

Nitrogen Fertilizer Timing for Grain Sorghum

This tip was provided by:

Calvin Trostle, Extension Agronomy, Lubbock, 806-746-6101,


Nitrogen Fertilizer Timing for Grain Sorghum

In the last Sorghum Tip I discussed the nitrogen requirement for grain sorghum production, which is different than how much N fertilizer you may apply.  A field may have N credits, most likely from soil test nitrate-nitrogen, which a Texas A&M AgriLife soil test will credit 100% to you grain sorghum N requirement.

Nitrogen fertilizer timing for grain sorghum can involve pre-plant application, sometimes well in advance of cropping (especially if using anhydrous ammonia, which is often cheaper per unit of N) and pop-up fertilizer (in-furrow) or starter N (placed near the seed).  Each have their place though conditions like the potential for water-logged soils and the time before planting can reduce efficiency for pre-plant applications.  See the Texas sorghum production guides below for information about safe use of at-plant N to ensure that toxicity or fertilizer salts do not hinder germinating grain sorghum and seedling growth.

For in-season application of grain sorghum, the key reference point that guides timing of N application is the changeover of the growing point from producing another leaf to initiating the head (Fig. 1).  In wheat (the same botanic family of grasses as grain sorghum), this generally occurs just before jointing, which you can see in wheat.  But in grain sorghum there is nothing visual externally on the plant that signals this is occurring.  Generally, this occurs about 30 to 35 days after planting.


Fig. 1. The growing point of grain sorghum after differentiation from leaf production to developing panicle, or head. This process initiates about 30 days or so after germination. In this image there is likely at most 2 days’ difference from left (early) to right. Spikelet number and potential seeds per spikelet—both important components of yield potential—are being determined for each head over a 7 to 10-day period.

Once growing point differentiation (GPD) occurs, the developing head must not be limited in needs for sufficient nitrogen (or water!), lest you cap your potential spikelets and seeds per spikelet, thus limiting your yield potential.  Once GPD concludes you cannot increase spikelet number and seeds per head.

Historical guidelines from Texas A&M, Kansas State Univ., etc. have suggested that side-dress N fertilizer applications be completed by about a month after planting to meet your crop’s targeted N requirement.  This can be a substantial amount of N for larger yield goals.  Though all remaining N is not needed right then at GPD, in-season N applications were generally only made once, so it was necessary to apply the remainder of your N fertilizer soon.

Today, particularly where N fertilizer applications may be conveniently supplied by dissolving in irrigation water, some producers may elect to withhold a portion of their in-season N fertility after GPD to spread out the N application and perhaps increase nitrogen utilization efficiency.  This could be up to 20% or so (an estimate on my part) of the N, but I would recommend that all remaining N be on the field by early boot stage.  This would be within 50 days of planting for a medium-early maturity hybrid and about 60 days for a medium-long maturity hybrid.  Kansas State Univ. research suggests that by the time late boot stage occurs 70% or more of grain sorghum’s required N will already be in the plant.

Further Information:
You can read additional information on several aspects of nitrogen fertility for Texas grain sorghum from the fertility sections of the West Texas and the South & Central Texas editions of United Sorghum Checkoff Program’s production guides, on the web at  The information is similar in both guides, which were prepared by AgriLife Extension staff.

Nitrogen Fertility Guidelines for Grain Sorghum

This tip was provided by:

Calvin Trostle, Extension Agronomy, Lubbock, 806-746-6101,


Nitrogen Fertility Guidelines for Grain Sorghum

In our four years of compiling Sorghum Tips, we should have addressed basic N requirements for grain sorghum long ago.  From the Sorghum Tips archive at, in 2012 we did discuss 1) fully crediting 100% of your soil-test nitrate-N down to 24” and the use of Texas A&M AgriLife’s Profile Soil Sample Information Form (Nov. 7, or page 7 of archive), and 2) the full N credit you can take for any nitrate-N in your irrigation water (Dec. 4, or page 6 of archive).

But what about the straight-up, season-long N requirement for grain sorghum?

Texas A&M AgriLife’s long-time fertility goal based on soil fertility research is tied to your yield goal:

2.0 lbs. of actual N per 100 lbs. of yield goal

This is a helpful rule of thumb—for planning purposes—for your N requirement.  Therefore, if you have a 5,000 lbs./acre yield goal, then the N requirement is 100 lbs. of N per acre, e.g.:

2.0 lbs. N/cwt.  X  50 cwts. = 100 lbs. N/acre

This is not the fertilizer N requirement as there are credits you may claim against the total required N.  In Texas A&M AgriLife these recommendations include:

  • Soil nitrate-N in your surface soil sample (usually 0-6”, sometimes 0-8”).  If you have 7 ppm nitrate-N in the top 6”, that is equivalent to 14 lbs. N per acre.  (Each 6” deep layer of soil is about 2,000,000 lbs. of soil; thus for each 1 ppm nitrate-N, you have 2 lbs. of nitrate-N.)
  • Sub-soil nitrate N (if you have the data, see #1 above).  For each 6” of soil below the six-inch depth, 1 ppm nitrate-N equals 2 lbs. of nitrogen per acre, a credit against the full N requirement.  For example, you have a sub-soil test sample of 6-18” deep at 4 ppm nitrate-N, then the credit determined, calculated as two 6-inch layers, is:

2 soil layers over an acre  X  4 N (from soil test ppm)  X  2 (ppm conversion factor)  =  16 lbs. N/acre

  • If you irrigate, you could also take a credit for any nitrate-N in the irrigation water (see #2 above).
  • Are there other possible N credits?  In Texas we don’t claim any, but a farmer sending a Kansas soil sample to Kansas State’s soil test lab will answer questions for soil texture, previous crop (if legume), and soil organic matter.  Each of these will slightly alter a KSU recommendation.

The full example—

For the 5,000 lbs./A yield goal…

Fertilizer N to apply  =  N requirement  –  soil test N (0-6”)  –  subsoil test N (below 6”)

70 lbs. N/acre  =  100 lbs. N/acre  –  14 lbs. N/acre  –  16 lbs. N/acre

What this example does not address—

This is the N requirement.  It does not address timing (most N should be on by growing point differentiation about 5 weeks after planting), fertilizer placement, or N use efficiency.  I will address these in a future Sorghum Tip.  In the interim, refer to the N fertility section of your region’s USCP pocket grain sorghum production guides for Texas at ).

2016 Texas Grain Sorghum Weed Control & Harvest Desiccation Guide

This tip was provided by:

Calvin Trostle, Extension Agronomy, Lubbock, 806-746-6101,


2016 Texas Grain Sorghum Weed Control & Harvest Desiccation Guide

As, we have noted before in a previous Sorghum Tips, we believe your most important weed control decision for grain sorghum is always pre-plant/pre-emerge herbicide applications.  Prevent weeds in the first place, and catch the escapes or other emerging weed issues later with over-the-top herbicides.  For most growers a combination of atrazine and metolachlor (Dual) gives good control, but many growers will substitute propazine on sandy soils and in cotton rotations.  The above document has been updated by Trostle/McGinty for use in planning your herbicide program with the active ingredients (and brand commercial names) available to your grain sorghum weed control program.  View/print/download the document at

Is Inzen/ALS-Tolerant Grain Sorghum Available in 2016?

The prospect of over-the-top grass control in grain sorghum has been teasing us for several years.  Five years ago we thought it would be here by 2014 or perhaps 2015 at the latest.  We are indeed closer to this sorghum’s availability, but only one limited opportunity exists for 2016.  First, this ALS-tolerant system has been named “Inzen” by Dupont, and eventually the active ingredient nicosulfuron (currently as Accent, soon as Zest) will be labeled for over-the-top application.

Currently, Pioneer does not have any hybrids that are available for growers, but Dupont licensed the technology to Advanta US, which has one hybrid (medium maturity) in their Alta Seed brand that is available on a limited basis for 2016 (one 50 lb. bag, maximum of 20 planted acres) if you are willing to partner with Advanta/Alta in a demonstration.  This will involve a stewardship agreement which governs what you can do with the grain (currently only for livestock feed or ethanol—it cannot go in to the commercial grain market yet), and, for now anyway, what you can rotate to next year (not sorghum).

If you are interested in this limited opportunity with Alta seed contact an Alta dealer.  You may be especially interested if you have a portion of a field where grasses are a special problem.  If any TGSA members try the technology this summer, please let your county ag. agent, myself & Dr. Ron Schnell know so we can learn from your observations.

2016 Sugarcane Aphid Watch–South and Central Texas

This tip was provided by:

Robert Bowling, (361) 265-9201,, Assistant Professor, Extension Entomology, Corpus Christi
IPM Extension agents Stephen Biles (Port Lavaca), Danielle Sekula-Ortiz (Weslaco) and Kate Harrell (Wharton)

South and Central 

2016 Sugarcane Aphid Watch 

Another season is upon us as farmers have begun seeding sorghum in the Lower Rio Grande Valley and Coastal Bend of Texas. Sorghum has emerged in the Valley and in some areas around Corpus Christi. Warm and dry conditions have made possible the early start to the season, especially when compared with the 2015 cropping year. How might these conditions influence sugarcane aphid infestations in sorghum?

Sugarcane aphid reproduction is favored by hot and dry conditions. Currently, sugarcane aphids have already been observed overwintering on Johnsongrass as far north as Hill County (Waxahachie).  Numerous cast skins in aphid colonies have been observed around Corpus Christi up to Austin County suggesting that sugarcane aphids are maturing and producing offspring. It is possible they will start moving to sorghum early this season.  What is the path forward to protect the crop from sugarcane aphid injury in 2016?

Our full first-of-the-season report on SCA for South & Central Texas is online at  Several additional SCA resources are also there including the Scout Card for use in field ID of SCA and the all-important Quick Aphid Checker to rapidly estimate the number of aphids per leaf.

Here are some additional points from our full write-up:

  • Know the aphid.  Use a magnifying lens for ID.  If honeydew is observed, look at the underside of the leaf above.  If the sugarcane aphid is found on Johnsongrass or volunteer sorghum start scouting sorghum shortly after plants have emerged.
  • Start scouting sorghum early! If the planting seed was treated with an insecticide seed treatment (which AgriLife generally recommends; the cost is spread out over many acres), the crop should be protected for 30 to 45 days.
  • Several grain sorghum hybrids have been identified as ‘tolerant’ to sugarcane aphid.  Be aware, however, that tolerance does not equate to immunity and all sorghum fields should be scouted for sugarcane aphid.  Ask your preferred seed company for their best tolerant material.
  • In-season insecticide options for managing sugarcane aphid are limited.  Sivanto (Bayer) is currently the most effective product labeled on sorghum and is safe to beneficial insects.
  • Carrier total volume of water applied to the field is important!  Complete coverage of all foliage is critical for maximum performance of an insecticide targeting the aphid.  Do not apply less than 10 gallons of final volume of spray solution per acre if treating with a ground rig and no less than 5 gallons per acre if applying by air (even if the product is labeled for 3 gal/acre or less).
  • DON’T BE COMPLACENT!  Last year in South/Central Texas was cool and wet.  SCA’s growth was slow thus insect predators to maintained sugarcane aphid populations at a low level.

Next Sorghum Tip (late Mrach):  Guidelines for sugarcane aphid in the Texas High Plains, where thresholds are lower, even just the Presence of SCA in the field (in contrast to a set number of SCA per leaf for South & Central Texas).

Part II: An Important Component of Weed Control that Doesn’t Involve Chemicals, Equipment, or even Weeds. II. Your Custom Applicator

This tip was provided by:
Calvin Trostle, Extension Agronomy, Lubbock, 806-746-6101,


An Important Component of Weed Control that Doesn’t Involve Chemicals, Equipment, or even Weeds.  II. Your Custom Applicator

Clear Communication is Important

In the last Sorghum Tip I discussed ensuring that your employees are clear on what needs to be done, that you cross-check with them on application practices, and even provide the means for your permanent employees to obtain their own pesticide applicator license and the training that goes with it.

Here are some key tips for working with your custom applicator:

Be clear with any commercial applicator you hire and ensure they understand what is needed and they are following label guidelines.  Confirm the rate of chemical you need applied.  Are their additives needed like AMS or crop oil?  If so, make sure.  I especially encourage farmers hiring custom application work to know what the label calls for as a minimum of carrier volume, whether by air or ground rig.  Expect—require—that your applicator use the minimum labeled rate for water per acre.  This is important for coverage; make sure you get what you are paying for.

Some labels unfortunately state a too-low carrier volume rate.  Here are two examples that reflect different reasons why carrier volume is too low and should be increased:

  • Dupont’s Prevathon, which better enables sorghum growers to attack worms in the whorl is labeled in Texas for 2 gallons per acre for aerial application.  Even Dupont staff in Texas disagree with this.  It needs to be at least 3 gallons per acre, and probably more for optimal coverage.  Unfortunately, since this is the labeled rate your custom applicator may balk without you paying more if you want 5 gallons per acre.  This is a dilemma, but if you are serious about achieving good insect control then carrier volume must be considered.  A poor application may require a second application.
  • Transform for sugarcane aphid.  If this insecticide becomes labeled again for use, Texas A&M AgriLife entomologists are in wide agreement that coverage is critical.  The labeled rate for aerial application for Transform is 3 gallons per acre, but our entomologist agree this is a situation with SCA that you need to apply 5 gallons by air (or 15 or more gallons/acre by ground vs.; 5-10 gpa is labeled).  So this is somewhat different situation than above in that SCA presents a special situation.  Also, there is wide agreement among AgriLife entomologists that different additives are merited (DowAgro agrees), but this information is not on the label, so you would need to relay this to your applicator to ensure they can follow best recommended practices.

Ready On-line Access to Chemical Labels for Agricultural Production
Herbicides, insecticides, seed treatments, fungicides, etc.  All in one place.  Chemical Data Management Systems maintains current full and Section labels at (click on Label Database, then type in the name of the chemical in the search box).  For additional use of this website, including instructions on how to search for chemicals by active ingredient (often a generic), consult the AgriLife Extension guide for using CDMS’ website at

An Important Component of Weed Control that Doesn’t Involve Chemicals, Equipment, or even Weeds

This tip was provided by:
Calvin Trostle, Extension Agronomy, Lubbock, 806-746-6101,


An Important Component of Weed Control that Doesn’t Involve Chemicals, Equipment, or even Weeds. I. Your Employees

I believe applicator awareness is often overlooked in weed control.  Communication and the needed instruction between a farmer and their own employees can make the difference in a serious mistake that damages a current crop or affects a planned crop rotation next year, or perhaps amounts to 85% weed control instead of the near 100% that you otherwise would expect.

Here are some tips as you work with your on-farm weed control team…

  • First, simply emphasize safety at all times.  On the farm I grew up on, I will admit that didn’t always happen.  I will admit that as a teenager I did some things that were stupid.
  • Confirm and cross-check with your staff which chemicals and any additives are being used.
  • Eliminate potential confusion about amount of chemical added to tanks, proper land speed, and issues involving calibration.
  • Ride the rig with your staff as much as is needed to ensure they are properly trained.
  • Communicate how important it is to fix plugged nozzles immediately (stop right there in the field!) and address other equipment issues; or in some cases that tank and system cleanout is conducted properly.
  • Teach your staff to stop and CALL YOU if something doesn’t look right.  Imagine one of your staff spraying dicamba on 16” tall grain sorghum with a hooded sprayer.  But the ground is rough and at the speed you are calibrated for the hoods are banging into the ground.  Instead of calling you, your employee raises the hoods 6” and sprays the field.  Now you have the risk that some crop loss may occur due to unacceptable contact of dicamba with the sorghum and potential blasted heads which don’t fill very well.

Asking confirmation questions of your staff—there is a right way to do this…

A good way to double-check with your staff that proper chemicals and amount are being prepared for application is to ask what has been done.  But how you ask will give you a more accurate indication of proper procedure and more likely identify if mistakes have been made.

Here is an example where you instruct your son/daughter or other employee to add a given amount, 2.0 gallons, of dicamba to a 300-gallon tank or spraying grain sorghum.  Now you want to ask if they did it right.

  • This is not a good question to ask:  “Did you add 2.0 gallons of Banvel to the tank?”  Why is this not a good question to ask?—because the employee can answer ‘Yes’ without revealing if they might have made a mistake.  Maybe they did make a mistake.  They added 2 jugs of Banvel (2.5 gallons each) to the tank.  An employee might realize they made a mistake and be afraid to admit it (even though the long-term consequences—severely damaged sorghum—are worse; but they might not know this could be a problem, or they will only be working for you through the summer then quit and go back to school, etc.).  This question may not have revealed the error.
  • Instead ask this question:  “What chemical and how much did you add to the tank?”  Now this is a question they can’t answer ‘Yes’.  They have to tell you something.  They will either guess (still might be right, but not likely), or they don’t know, or they will tell you the wrong thing.  Now you have a good chance of knowing if a mistake has been made.  If the sorghum field hasn’t been sprayed yet, you can avert a potential disaster.

Investing time and training in your employee that handles spray duties, and rewarding them…

For your family member (even a teenager) or permanent staff that helps spray your crops:

  • Have them study and train on your timeclock for their own pesticide applicator’s license.
  • Arrange for them to take the test.
  • When they pass it give them one-time bonus ($250?) or an annual supplement.  This tells your employee he or she has increased value as part of your team and that you value their new skills.  Increased training and sense of value on the part of your employee might avert a crucial mistake that could cost tens of thousands of dollars.
  • Have your newly licensed applicator help you maintain your records for TDA.

In my next Sorghum Tip I will discuss some pointers for interacting with your custom applicator.

Ready On-line Access to Chemical Labels for Agricultural Production

Herbicides, insecticides, seed treatments, fungicides, etc.  All in one place.  Chemical Data Management Systems maintains current full and Section labels at (click on Label Database, then type in the name of the chemical in the search box).  For additional use of this website, including instructions on how to search for chemicals by active ingredient (often a generic), consult the AgriLife Extension guide for using CDMS’ website at


Evaluating if Grain Sorghum Hybrids with Seed Company Designation of Tolerance/Resistance to Sugarcane Aphid Are Right for You in 2016

This tip was provided by:
Calvin Trostle, Extension Agronomy, Lubbock, 806-746-6101,

Ron Schnell, State Cropping Systems Specialist, College Station,  (979) 845-2935,


Evaluating if Grain Sorghum Hybrids with Seed Company Designation of Tolerance/Resistance to Sugarcane Aphid Are Right for You in 2016


In our last Sorghum Tip we published a list of 19 hybrids that companies have designated as what they believe are there most likely tolerant/resistant hybrids to sugarcane aphid.  Since then, as a Texas A&M AgriLife Extension staffer, I recognize that we in AgriLife don’t have enough information (or any in several cases) to publish about these hybrids’ tolerance/resistance and SCA.  Thus as a needed Disclaimer on the AgriLife December Sorghum Tip, though AgriLife staff have contributed to information (hybrid trial data, aphid and damage ratings, field observations) to the information Dr. Bean, USCP compiled, we in AgriLife have not verified the company information as well as other sources ourselves, and we have no AgriLife data of any kind on about half of these hybrids.

As an alternative I have written an article with the above title that discusses how you the producer may evaluate whether one of the 19 grain sorghum hybrids noted above is right for you.  Read the full edition at (posted title is “Grain Sorghum Hybrid Selection and Sugarcane Aphid 2016).

As a sampling of the document’s advice, here are five questions you can ask your grain sorghum seed dealer:

1)    “What hybrid(s) do you have with a proven SCA resistance gene in its parentage?”

2)    “If you do, does that genetic background transfer actual hybrid resistance to SCA in the field?”

3)    “What field evidence do you have for this hybrid’s substantial tolerance/resistance? Seedling tests?  Field observations?  Field insect counts?  Yield data?”

4)    “Is at least some of your field data from independent or external sources?” (If so, who?)

5)    “How does the yield of your current SCA tolerant/resistant hybrid(s) compare to your company’s best grain sorghum hybrids?” (Agronomically, you want to understand the grain yield potential of good grain sorghum hybrids even if susceptible to SCA vs. tolerant/resistant hybrids.  If there are significant yield differences be sure to ask/understand if those differences may be due to likely lower-yielding shorter maturity in a hybrid.)

The list of 19 sorghum hybrids noted above that have stronger claims about SCA tolerance/resistance will be maintained by United Sorghum Checkoff Program,, and it may change with additions and deletions.

Texas A&M AgriLife Grain Sorghum Yield Data & Sugarcane Aphid Tolerance/Resistance


Planting resistant or tolerant hybrids will be vital for long-term management of sugarcane aphid in sorghum.  As noted previously, USCP has provided a list of grain sorghum hybrids that are believed to have some level of tolerance to sugarcane aphids.  However, identifying well-adapted hybrids with consistent yield performance in your region will remain the most important criteria for hybrid selection.  You should not sacrifice significant yield potential to plant resistant or tolerant hybrids.  There is no guarantee significant pest pressure will materialize and no guarantee that treatment for sugarcane aphid will be avoided.

The Soil & Crop Sciences Department’s Crop Testing Program collects information on grain sorghum hybrid performance from more than a dozen locations across Texas each year.  Results can be found at:  In addition, hybrids identified as having unspecified levels of tolerance to sugarcane aphids will be summarized along with several susceptible public checks. These results will be available at the website above by the end of the week of January 18th.  Again, consistent yield performance will be the most important criteria when selecting hybrids.  Hybrids that perform well across multiple locations (regional summaries) and years (2- & 3-year summaries) should be strongly considered.  Make sure to select a hybrid that has a maturity rating appropriate for your environment. Several early to medium-early hybrids listed in the USCP report may be appropriate in certain situations (dryland and later plantings in west or south Texas).

Which Grain Sorghum Hybrids have Significant Apparent Tolerance/Resistance to Sugarcane Aphid?

This tip was provided by:
Calvin Trostle, Extension Agronomy, Lubbock, 806-746-6101,


Which Grain Sorghum Hybrids have Significant Apparent Tolerance/Resistance to Sugarcane Aphid?

Dr. Brent Bean, agronomist, United Sorghum Checkoff Program (and formerly Texas A&M AgriLife Extension agronomist, Amarillo), has compiled an initial list of grain sorghum hybrids that appear to have significant tolerance/resistance to sugarcane aphid (SCA).  Some other hybrids may have a lesser degree of tolerance, but those are not listed.  Dr. Bean has visited across the Sorghum Belt with companies, state university staff, farmers, etc. to arrive at this list as of Dec. 17, 2015.  Producers should consult the USCP website,, for possible updates beginning in early January.

Before I say anything else about how to use this list or how it was derived, know this: All commercial grain sorghum hybrids, including these listed below, have at least some level of susceptibility (and most are highly susceptible) to sugarcane aphid.  All hybrids must be scouted, and at this time the same treatment thresholds apply to these hybrids as any other.  No commercial hybrid is immune to SCA.  Some Texas farmers made the mistake of assuming too much about the early purported tolerant hybrids in 2015, and they failed to treat SCA in timely fashion, or even scout their fields regularly if at all.
*Please note the following list is in alphabetical order by company and the order is not associated with believed tolerance levels.

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Understand the Potential Caveats of this Initial List of SCA-Resistant/Tolerant Hybrids

  • Much of the above information is derived only from seedling tests conducted in a controlled setting in a growth chamber or greenhouse.  Real life conditions in your field are not a guarantee that the hybrid will demonstrate the same level of tolerance/resistance.
  • Several of the above hybrids also have documented favorable reactions to SCA in field conditions, and additionally, there may be numerous reports from producers, Extension staff, field scouts, and crop consultants noting an individual hybrid performed well relative to other neighboring hybrids, etc.  Dr. Bean notes that in most cases these hybrids have exhibited the ability to withstand higher infestation populations of SCA while retaining their yield potential, or SCA has been shown to increase in number much slower than in susceptible hybrids.
  • You may hear a producer or other agriculturalist disagree with a hybrid being included on the above list.  Know that these hybrids probably can’t tolerate/resist heavy SCA infestations on their own.  For example, Dekalb DKS 37-07 has numerous documented and anecdotal observations of reduced SCA activity (not sprayed as soon, sprayed once instead of twice relative to other hybrids, not sprayed at all), but an elevator manager told me Dec. 16 that he thought that 37-07 had the same level of problems as any susceptible hybrid.
  • Visit with the seed company about the hybrids you are interested in.  Ask them what evidence they have for the hybrid’s tolerance/resistance.  Seedling tests?  Field observations?  Field data?  Do they have new information on any other hybrids?
  • Regardless of a hybrid’s tolerance/resistance to SCA it is still critical to chose a hybrid based on its local adaptability and other favorable characteristics.

In our next Sorghum Tip in January we will provide a link to a summary of yield data comparisons for the above hybrids vs. trial averages from the Texas A&M AgriLife Crop Testing Program’s sorghum hybrid performance tests.  (Most of the individual trial reports are already posted at )

Texas Plant Disease Diagnostic Lab (TPPDL) vs. Direct Assessment by Sorghum Disease Experts
In our last Sorghum Tip we noted the services of TPPDL.  Dr. Isakeit noted that this service lab is in part oriented toward horticultural assessments.  You may wish to call your regional Texas AgriLife disease specialist (contact info. in previous Tip) to inquire if you might submit samples directly to Drs. Isakeit (College Station), Odvody (Corpus Christi), or French (Amarillo).

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