Sorghum Tips

Huskie Herbicide: Major Addition for Weed Control in Texas Grain Sorghum – 2013 Update

Statewide

In our very first TGSA Sorghum Tip last year we highlighted to producers the opportunity to use Huskie herbicide in grain sorghum (see here). Since the end of the 2012 cropping season, numerous producers have commented they were well satisfied with Huskie’s control. Here is a sampling of common comments from producers as well as the Huskie manufacturer, Bayer Crop Science.

  • Low to modest Huskie injury on grain sorghum was acceptable. A quick flashing, or burn, of the leaves was not uncommon, but injury levels were modest, and the grain sorghum quickly grew out of the injury with no apparent lasting effect on grain sorghum.
  • Producers were largely well satisfied with overall weed control. This included Palmer ameranth, other pigweed species, morningglory, Russian thistle.
  • Good control of glyphosate-resistant Palmer ameranth is a primary attribute of Huskie. This allows producers to more safely use herbicidal modes of action when they rotate grain sorghum.
  • Were there any problems or dissatisfaction with Huskie? In the High Plains there were but a few producers that were not pleased, but the common thread among their comments were:  a) dryland (especially in a major drought year), b) weeds were hardened off, and/or c) the sorghum itself was not doing well and not actively growing in some cases.

What to expect in the future for Huskie in Texas grain sorghum?

Bayer suggests that for optimum weed control, use:

1 pint of Huskie  +  1 pint of atrazine  +  1 lb. of ammonium sulfate (AMS) per acre

This rate of atrazine might be a concern for farmers on sandy loam to loamy sand soils; however, Texas AgriLife as well as Bayer staff has not observed any apparent issues with atrazine as long as the applicator follows the labeled rate.

Rotation to cotton on the Huskie label remains at 18 months or field bio-assay. Texas A&M AgriLife and Bayer staff have not yet observed any significant rotation issues to cotton.

There is consideration of expanding the Huskie label for applications up to flag leaf emergence.  Though this might be appealing to producers, we should only view this as a potential rescue treatment. Waiting until nearly flag leaf emergence means that pigweed and other problem weeds will be larger, thus harder to kill. Weed control will more likely be incomplete.

Watch for an upcoming Texas A&M AgriLife survey of 2012 Huskie users to share their experience with this herbicide. This will likely merit an additional mid-season Huskie sorghum tip.

Narrow Row Grain Sorghum – Increase the Seeding Rate?: Probably Not

Statewide

A frequent question across Texas is whether a grain sorghum producer should increase the seeding rate if moving to narrower row spacing. Most Texas grain sorghum is planted on 30-, 36-, 38-, or 40-inch rows.  In general, Texas A&M AgriLife recommends that you do NOT increase the per-acre seeding rate when moving to narrower rows for several reasons:

  • Many producers are actually already dropping as much if not more seed than they probably need for good production.
  • If moving to a narrower spacing, let the additional space around the individual plant be the means of compensating for slightly higher yield potential. Grain sorghum does indeed compensate, and if there is more space around an individual plant, the plant will likely tiller more in response to the environment.
  • Maintaining the same per-acre seeding rate is easier if you are using an air-vacuum planter that meters the seed and also has the same or similar equipment to achieve good placement of the seed.
  • What about drilling grain sorghum seed?—In this case producers must be careful.  We like the idea of spreading your plants out, however, most drills were not made to drop such small amounts of seed, 5 lbs. down to as little as 2 lbs., per acre. Drills measure volume of seed, not seed number. You probably can’t get most drills shut down enough, especially if they are older and worn some. If you are drilling, expect to tape or close off at least 1 of 3 drops and perhaps 1 of 2 drops. Drills do not place seed as well as planters, hence reduced seedling establishment may be expected, especially if not irrigated. Due to reduced optimum seed placement, I will allow an increase in per-acre seed drop by 10% – in other words, not much!—if you are drilling. If seedbed conditions are truly rough, then perhaps 20% increase in per acre seeding rate; however, if you get a good rain, and it all comes up, you are immediately over-populated. (If field conditions are truly rough, then use the planter anyway for managing the best seed placement you can get.)
  • Moving to narrow row spacings means you forego the opportunity to conduct mechanical cultivation for weed control. Thus you have a question of narrow row spacing for weed suppression vs. retaining the ability if needed to cultivate. Since grain sorghum has few aerial over-the-top weed control options, if you anticipate weedy issues, you may prefer to not close the door on cultivation if it becomes necessary.

Grain Sorghum Seed Size

Statewide

Seed size in grain sorghum ranges from about 12,000 to 16,000 seeds per pound. Grain sorghum in general will sometimes have slightly smaller seed size (18,000 seeds per pound). Usually seed companies will select what they believe is their best seed to bag for your planting and so this tends to be the larger seed. Planting seed size for hybrid seed most commonly runs about 13,500 to 15,000 seeds per pound. For planting seed I am most likely to assume 14,000 seeds per pound if I don’t know the specific number.

Seed size should not really affect a farmer’s decision on which seed to select. Good germination is much more important. Seed and subsequent seedling vigor is not necessarily higher with larger seed size though as a grower we would likely feel more confident in a larger seed. No correlation has been demonstrated between seed size and eventual yield. In dry conditions, larger seed needs to imbibe more moisture to germinate, but this is not normally an issue for grain sorghum. It can be with larger seeded crops like soybean or sunflower.

The one caveat about large grain sorghum seed is that at 13,000 seeds per lb. versus smaller seed at 15,000 seeds per lb., is the larger seed has 13% less seed in a bag so it will not plant as far (essentially costs about 13% more to plant) when using an air-vacuum planter. If you have an older planter that uses plates, your pounds-per-acre seeding rate will stay the same but the seed drop will decrease. Because many Texas producers plant more than enough seed, I would not worry about the slight reduction in seeding rate. Plate planters should be calibrated to ensure they are delivering the desired amount of seed regardless of seed size.

Grain Sorghum Seed Costs & 2013 Supply

Statewide

No kidding, seed is in short supply for 2013 due to reduced hybrid seed production in both 2011 and 2012. An increased in expected acres will further shorten supplies. This has created the highest grain sorghum seed cost we have ever seen.

Action Tips for Grain Sorghum Seed:

  • If you anticipate needing grain sorghum seed in 2013 I urge you to check with your preferred seed dealer now.  Supply is declining and prices are subject to change (they won’t be going down!). The longer you wait, the less selection you will have.
  • Be cautious about moving to a maturity of grain sorghum seed that is not appropriate for your production system. In Central & South Texas if all you can find is early maturity hybrids, then call another dealer. In the High Plains, don’t book a medium-long or long season hybrid for dryland just because that’s all you can get.
  • Evaluate your seeding rate.  For grain sorghum seeding rate targets in your area, consult the three different United Sorghum Checkoff Program grain sorghum pocket guides that cover Texas here. {These include editions for South & Central Texas, West Texas (South Plains, Concho Valley, Rolling Plains), and the High Plains (Texas Panhandle)}. Many producers in Texas still plant more seed than they need, sometimes at the expense of grain yield. I would rather pick a preferred hybrid and reduce the seeding rate by 20% to stretch a limited supply of seed than go with something I am not familiar with or is less appropriate.

Here is a sampling of grain sorghum seed prices from four seed companies with Texas sales.  This represents both regional and national brands. Prices are the same across Texas.

  • Company #1:  Concep III treated seed only (allows use of Dual Magnum herbicide), $109/bag. Gaucho or CruiserMaxx treated, about $159/bag.  Three of six primary hybrids sold out, 1 is thin, 2 with modest supply. Discount 6% if paid by 12/31, 4% discount if paid Jan. – Feb.
  •  Company #2:  $100 to $135/bag, depending on hybrid.  Add $18/bag for Concep III.  Gaucho treatment about $13-15/bag. Other premium comprehensive seed treatments somewhat higher than Gaucho. Seed supply is extremely short, and some hybrids are sold out. No pre-pay discounts as seed supplies are too short.
  • Company #3:  All hybrids are $172-184/bag which have Concep III and CruiserMaxx.  They don’t sell grain sorghum seed any other way. All medium maturity hybrids sold out (at least in High Plains), but some supplies left of medium-early and medium-long.  7% cash discount if paid by Jan. 18, and quantity discounts available.
  • Company #4:  $102/bag for older lines, $110/bag for newer lines, all Concep III treated. Up to $64/bag for Poncho treatment. Seed supplies low and company will re-allocate remaining seed stocks in early January. Call about discounts.

“Free” Nitrogen for Grain Sorghum (Irrigated) #2 – Nitrate N in Irrigation Water

Statewide

In my previous tip I noted the value of existing subsoil (below 6”) nitrate that is readily available to grain sorghum and other crops, which should be fully credited to grain sorghum N requirements nor soil nitrate between 6” and 24” deep.  Now for irrigated crop producers, let’s consider the amount of nitrate-N (also expressed as nitrate-nitrogen or NO3-N) that potentially exists in irrigation water.  This N—like soil N—should be fully credited to crop production with only a minor exception or two.

For reference read the three-page Extension publication “Nitrates in Irrigation Water:  An Asset for Crop Production” (Texas A&M AgriLife Extension Service, E-619, type ‘nitrate’ in the search box at http://agrilifebookstore.org).  This recent 2012 document explains the justification for valuing nitrate in irrigation water, which by reducing fertilizer N requirements, can save producers input costs.  Most Texas irrigation waters contain 3 to 10 parts per million (ppm) nitrate-N, but some waters are over 20 ppm.

In general, for each 1 ppm of nitrate-N in your irrigation water you are adding 0.23 lbs. of N per acre.  A producer who irrigates 12” and has 6 ppm nitrate-N in the water is applying about 14 lbs. of N per acre.  For a 6,000 lbs./A yield goal, this level of long-term N concentration is about 12% of your total crop requirement.  The cost of N fertilizer, were you to buy it, would currently be about $9/acre for this example, and that does not include application costs.

“Free” Nitrogen for Grain Sorghum Production #1 – Soil Profile N

Statewide

Across Texas crop consultants, producers, AgriLife staff, etc. are becoming more aware of the potential for accumulating nitrate-nitrogen (NO3-N) in the soil.  This nitrogen has value for your sorghum and other crops.  “Profile N” is nitrogen accumulating below standard soil sampling depths, most often 6”.  This accumulation is due to over fertilization (or underutilization in years when production is sub-par) with N, and the majority of the time producers are not aware of the presence of this N in the soil.  Historically this N is not accounted for in supplying crop nutrient requirements, but it should be.

The level of N accumulation can vary greatly due to fertilization practices, downward percolating moisture from rains which carries the soluble and mobile nitrate, soil type, etc.  Sometimes substantial N is found even below 3’ in the soil, but only deep rooted crops can tap that N.  Texas A&M AgriLife’s Soil, Water, and Forage Testing Lab offers a “Profile Soil Sample Information Form” (SP12) that pairs your standard 0-6” soil sample (analyzed for multiple nutrients including N, P, etc.; routine analysis, $10) with a second soil sample from 6” to as deep as 24”.  This paired soil sample is analyzed for nitrate-N only, $4.  The submitter marks the depth to a proper calculation of nutrient requirements can be made by the soil test lab.

Is profile nitrate-nitrogen down to 24” deep 100% available to grain sorghum?

Yes.  Even slightly deeper N is largely available.  The Profile Soil Sample form for N credits any 6-24” N to your crop requirement thus reducing fertilizer costs.  Extension recommends that producers include at least some profile soil N sampling to establish whether there might be deeper N present.

The current Profile Soil Sample form is found at http://soiltesting.tamu.edu/files/profilesoil.pdf

2012 Grain Sorghum Hybrid Yield Trials

Statewide

Texas A&M AgriLife’s Crop Testing Program (http://varietytesting.tamu.edu) annually conducts fee-based hybrid performance tests across Texas.  These replicated tests also report multi-year data for up to three years at most locations. With increased interest in grain sorghum for 2013, visit the above website and click on ‘Grain Sorghum’ to learn about trials in your region.  Results for 2012 to date—all including a 3-year summary—are posted for Monte Alto, Gregory, Thrall, College Station, and Farmersville.  Results are forthcoming from Uvalde, Danevang, and High Plains irrigated and dryland locations.

Producers in the Texas Coastal Bend may contact extension agronomist Dr. Dan Fromme, Corpus Christi, (361) 265-9203, dfromme@ag.tamu.edu, for a copy of results of additional hybrid trials he coordinates with county Extension agents in his area.

What about seed company hybrid trials?—Numerous companies have in-house tests which focus primarily on their own hybrids but often include a few competitor’s hybrids.  Though these trials are not considered ‘independent’ in the sense that a farmer or researcher would desire, these trials have an important role in identifying performance leaders within an individual company’s hybrid selections, especially as new hybrids are released that must be compared to the company’s old favorites.

Early Freeze & Frost (High Plains)

High Plains

The Freeze & Frost of October 8, 2012

An unexpected heavy frost/freeze occurred in the lower High Plains region on October 8th.  Due to later plantings, often after failed cotton, many acres were subject to extended hours of frost and freeze.  Lubbock recorded the second earliest freeze on record (average first freeze is Oct. 31).  Texas Tech Univ. “Mesonet” weather stations (http://www.mesonet.ttu.edu) recorded lows of 28°F at Muleshoe, Floydada, Hart, and as far south as Tahoka.

Frost damage and termination of grain sorghum is well known in the High Plains but rarely catches much sorghum that is not yet mature.  Early assessment suggests significant foliage damage is present.  How some sorghum fields respond may depend on stalk (culm) survival from the head down into the foliage.  If the culm survives the freeze then the plant can continue to deliver nutrients and carbohydrates to the developing grain.  But at a minimum, I expect reduced test weights on many acres of grain and in some cases little to no further grain development as the grain will now simply dry down without further starch accumulation.  This is particularly a concern as numerous fields appear to be in the range of seed development at 20% hard dough/60% soft dough/20% milk stage, with 5% of the total grain at black layer (physiological maturity).  Fields that show evidence of major injury which were likely >50% milk stage should be considered for hay or grazing.

For additional information on handling grain sorghum damaged by a freeze, consult “Harvesting Grain from Freeze-damaged Sorghum (~2001)” from Kansas State Univ., http://www.agronomy.ksu.edu/extension/p.aspx?tabid=86.  This includes decisions for low test weight grain sorghum, which is price discounted, and may be rejected outright if test weight is <50 lbs./bushel.  If faced with low test weight, compare discounts among local and regional grain buyers.  Allow time to take a preliminary test cutting to assess your test weight.  If low, you may reset the combine to blow out more of the lighter immature kernels.

Freeze damaged grain sorghum on a pound-per-pound basis has similar feed value to mature grain, however, the small kernel size makes grinding more difficult in order to crack the seed and capture the grain’s full nutritional value.

Texas AgriLife will post additional information on the regional grain sorghum freeze discussion at http://lubbock.tamu.edu in mid-afternoon on October 10th.

Nitrates & Prussic Acid in Forages, E-543 (2012)

Statewide

Applications in Sorghum Forages

When nitrates and prussic acid accumulate in forage, the feed may not be safe for livestock consumption. This Extension document—available for view, print, or download at https://agrilifebookstore.org/ (then use the search box) —highlights the symptoms of nitrate and prussic acid poisoning.

Prussic acid (cyanide) occurs primarily when a strong frost hits sorghum family forages or grain sorghum.  It can also occur in fresh growth on drought-stressed forages.  Cattle normally need to be off the forage at least 1 week after a frost or freeze, and properly cured hay should be OK.  Testing for prussic acid is tricky because handling the forage can lead to decomposition of the prussic acid.  If you need a prussic acid test decide first which lab you are going to use and call them ahead of collection for their instructions.

Nitrate accumulation in sorghum and sorghum hays is most likely in rainfed conditions when either significant N applications have been made or the crop is drought stressed but still accumulating N.  Nitrate is likely accumulated in the base of the stalk, so simple measures to use this forage include raising the cutting height 3-4”.  Drought stressed grain sorghum in the High Plains that may be used for hay should consider testing the forage for nitrate accumulation in 2012.

Grain Sorghum & Low Input Mentality

Statewide

Numerous producers in all regions of Texas are already considering increasing their grain sorghum acreage in 2013.  Cotton price prospects for 2013 do not appear strong and grains do.  Aflatoxin concerns have backed some growers off of corn in Central and South Texas.  Producers are already checking seed supplies of favorite sorghum hybrids for next year.

A pitfall to avoid, however, for grain sorghum production is going too far into the too-common low-input mentality for grain sorghum production.  For too many producers, this in fact approaches a no-input mentality.  Or at least minimal inputs.  This applies foremost to nitrogen (N) fertilizer, but can affect P fertilizer, the willingness to spray for insects like headworms or stink bug when economic thresholds suggest you should, etc.  Yes, grain sorghum production at the yields we expect on an acre is less than for corn.  But we know that if inputs are cut significantly below crop requirements then you receive mediocre and even poor results.  And then the tendency is to blame the crop for underperformance.

I attended the recent national grain sorghum conference at Kansas State University.  Colleagues with KSU as well as Oklahoma State Univ. spoke highly of grain sorghum’s role in Great Plains farming, that sorghum has a fit in many production systems that is more appropriate than corn.  But they noted producers must ensure inputs are managed appropriately to maintain good profitable yields else reduced inputs restrict yield potential and lead to disappointment.

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