Category Archives: Grain Sorghum

Inzen Z Grain Sorghum And Zest Herbicide

The EPA recently approved the use of Zest herbicide for use in the Inzen Z ALS-tolerant grain sorghum system.  The following are some questions and answers from UGA Extension Weed Sceintist Dr. Eric Prostko that may be helpful to us:

1) What is Inzen Z herbicide-tolerant grain sorghum?

Inzen Z herbicide-tolerant grain sorghum is sorghum that has been traditionally bred (i.e. NON-GMO) for resistance to certain ALS-inhibiting herbicides. This technology was originally developed by Kansas State University and licensed to both DuPont and Advanta Seeds. The resistance to these herbicides came from ALS-resistant shattercane, a close relative of sorghum.

2) What is Zest herbicide?

Zest is a new liquid formulation of the active ingredient, nicosulfuron.  You may recall that nicosulfuron is the active ingredient of the old corn herbicide sold under the trade name of Accent. Nicosulfuron is also an ingredient of several other corn herbicide pre-mixes such as Steadfast Q (nicosulfuron + rimsulfuron) and Revulin Q (nicosulfuron + mesotrione).  The use of Zest herbicide on conventional grain sorghum varieties will result in severe crop injury/death (Figure 1).  At the time this blog was penned, a Zest label was not yet available.  The official Zest label is anticipated in April?


Figure 1. Weed control in Inzen Z grain sorghum with nicosulfuron in 2013. Conventional sorghum variety in right picture was completely killed by nicosulfuron.

3) Has the Inzen Z herbicide-tolerant sorghum been tested system in Georgia?

Yes! UGA weed scientists have worked with this technology for several years.  When available, it will be very beneficial for grain sorghum growers who struggle with Texas millet/buffalograss control.  However, resistance management will be crucial to the long-term viability of this technology. Georgia growers will be encouraged to start clean, use a residual herbicide at planting (Dual or Warrant), tank-mix atrazine with the POST application of Zest (Figure 2), and rotate crops.


Figure 2. Weed control in Inzen Z grain sorghum – 2014.

4) Will Inzen Z grain sorghum hybrids be available to Georgia growers?

Since Georgia is not a leading producer of grain sorghum (only 50,000 acres planted in 2015). I expect our growers will be on the end of the list in terms of getting hybrids that are well-adapted to our region.  In 2016, Advanta (Alta Seeds) is scheduled to release one Inzen Z hybrid to a small group of growers in Kansas and Texas.  In 2017, Advanta hopes to launch an additional two Inzen Z hybrids. Pioneer will potentially launch in 2018.


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EPA Orders Cancellation Of Sulfoxaflor (Transform)

By Angus Catchot, Extension Entomologist, Jeff Gore, Research and Extension Entomologist and Don Cook, Research Entomologist November 13, 2015

– See more at:

By now many of you may have heard that Sulfoxaflor, the active ingredient in Transform, recently lost a major court decision in the Ninth Circuit Court of Appeals. The suit was led by the Pollinator Stewardship Council, beekeepers, and other bee advocacy groups. To sum up the decision, the courts ruled that the EPA did not have substantial evidence that the products effects on bees had been studied sufficiently prior to registration.

What does this mean for the (growers)?

Cotton: Over the last several years Transform has proven to be a highly efficacious product against the Tarnished Plant Bug and Cotton Aphid. It has essentially replaced 1-3 dicrotophos and acephate sprays for plant bugs in the MS Delta region.

Grain Sorghum: Transform is essentially 1 of the 2 (Sivanto) only available options to control Sugarcane Aphids in grain sorghum (a new devastating pest of grain sorghum). This will increase the likelihood of resistance to Sivanto substantially in the coming year.

At this time it is not clear what choices growers will have for 2016 but this decision no doubt will affect our overall IPM program for next year. As growers have begun to find out about the cancelation of Sulfoxaflor, many growers have expressed concern and frustration. As we learn more we will share.

From the EPA:

Sulfoxaflor – Final Cancellation Order

On November 12, 2015, EPA issued a cancellation order for all previously registered Sulfoxaflor products. Pursuant to EPA’s cancellation order, and beginning November 12, 2015, distribution or sale by the registrant of cancelled sulfoxaflor products is prohibited, unless such distribution or sale is for the purpose of disposal or export. Also, stocks of cancelled products held by persons other than the registrant may not be commercially distributed in the United States, but instead may be distributed only to facilitate return to the manufacturer or for proper disposal or lawful export. Use of existing stocks by end users is permitted provided such use is consistent in all respects with the previously-approved labeling for the product.

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Sugarcane Aphids in Grain Sorghum

Seminole County Agent Rome Ethredge shared my poster on sugarcane aphids on his blog.

Seminole Crop E News

Sugarcane aphids have been a real problem in grain sorghum since they came in last year. Thomas county Agent, Andrew Sawyer had a good poster at a meeting this week and I will post it here. He found a beneficial wasp that is working to help us control the aphid and that’s good news.

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Grain Sorghum Dessication


We still have some late grain sorghum left to harvest and we’ve been talking about dessication. We discussed this with UGA Extension Weed Scientist Dr. Eric Prostko who has received more questions this year about the dessication of grain sorghum. Dr. Prostko says, “Growers need to know that the use of harvest-aids in grain sorghum has shown little effect in reducing grain moisture content.”  A summary of 2 older papers is as follows:

1) Hurst, Harold.  1991.  The Use of Dessicants For Field Drying Grain Sorghum With and Without Weeds.  Mississippi Agricultural and Forestry Experiment Station Bulletin #974.

“Overall, these studies did not result in any distinct advantage for application of dessicants to reduce grain sorghum moisture.”

2) Olson, B.L.S, T. Baughman, and J.W. Sij.  2001. Grain Sorghum Dessication with Sodium Chlorate and Paraquat in the Texas Rolling Plains.   Texas Journal of Agriculture and Natural Resources 14:80-83.

“Results from our 2-year study indicate that dessicant applications were generally ineffective (and most likely uneconomical) in reducing grain moisture in late-planted grain sorghum.”

In my opinion, the major (only?) benefit of using a harvest-aid in grain sorghum would be to reduce the amount of green plant material that goes through the combine and might end up in the grain.  I know of only 3 things that will dry down grain sorghum seed: time, a hard freeze, and/or a grain dryer.”

When we treat as a harvest aid, keep in mind that the grain needs to be past the milk stage of development. Dr. Prostko recommends treatment as close to harvest as possible to lessen the chance of morningglory regrowth.

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Grain Sorghum Harvest


We are almost done harvesting milo for grain in Thomas County. This is the first season all of us have dealt with sugarcane aphids from beginning to end. The majority of fields in the county have been treated 4 times for aphids. This does seem like a lot of sprays; however, in these fields, yield reports are good. In these fields, SCA was spotted early and treated at or below threshold.

There was a few fields that were treated late, according to threshold. SCA reached the top of the plant before spraying. A couple of weeks later, the lower leaves completely desiccated due to aphid pressure. These yields are much lower than average. Other reports are were volume is high, 17%-19% moisture, test weight is low. Could this be from SCA?

UGA Extension Entomologist Dr. David Buntin says, yes, this can be the result of SCA. However, test weight be also be related to wet and dry cycles. And this season will certainly be marked by wet and dry cycles. Another issue we have noticed are small heads and large heads. Dr. Buntin says when heads are in two or three different stages of growth, this is result of SCA. SCA don’t have huge phytotoxic effect of feeding, but lots of feeding over time delays heads emerging.

At this stage, we still need to check heads for aphids. Mississippi saw a 20% yield reduction when aphids persisted into the heads.

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Sorghum Heading – Scouting For Insects

Sorghum 017

Our early planted sorghum is heading now and is past flowering stage. We are looking at a few different insect pest I want to write about. Some fields have sprayed 3 times now for sugarcane aphids. At this point, we want to watch for aphids in the grain heads. Also we are seeing caterpillars in grain heads. Last week, we were checking for midge.


Midge can be more difficult to scout for. Once grain heads come out, we need to be looking for midge. Once flowering is complete, midge is not an issue. One way to scout is take a paper plate, and slap the head in the plate. Dr. Angus Catchot, entomologist in Mississippi, shows on Scouting For Sorghum Midge With Confidence, a method of putting a gollon ziplock bag over the grain head and thumping it. The midges fly to the top of the bad, and you don’t have to close the bag.

Scouting for midge

Scouting for midge

UGA Extension Entomologist Dr. David Buntin says we need to avoid pyrethroids and insecticides that would flare aphid populations. Do not do automatic sprays for this reason.

Sorghum Midge - Photo by Ben Thrash

Sorghum Midge – Photo by Ben Thrash


We are also seeing caterpillars on the grain heads. Most of the caterpillars we are seeing are corn earworms. We were also seeing armyworms. Our threshold is to treat when an average of 1 or more (1/2 inch or larger) of any of these worms are found per grain head. Below is a photo of corn earworms on this head. Flowering is complete here, and they blend in to the grain.

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Sugarcane Aphids

One of the four fields we checked yesterday is at dough stage of development. Dr. Buntin says when we get to dough stage, we do not have the concern for sugarcane aphids. We still need to check for aphids in the grain heads, because of issues with harvest equipment from aphid honeydew. Here is a photo of some aphids in the grain head. This field is in the dough stage and past flowering, so pre harvest intervals are more difficult as we move to heading.


Some milo fields have been sprayed three times for sugarcane aphids. It is difficult to assess thresholds following a devastating 2014 season where aphids hurt us before we knew what was going on. However, Dr. Buntin believes we should be able to get SCA with two sprays during the season. We have learned to scout by not only checking aphids on a plant, but walking fields and looking for honeydew. It is easier to see honeydew on the leaves from a distance and you can check more than one row at a time. Where honeydew exists, this indicates a high aphid population – one that is treatable. Below is a photo of sooty mold on leaves. Sooty mold grows on the honeydew left from aphids. This is another indicator, however, I have not seen sooty mold show up until now. This is not an issue for the plants, just sign of aphids.

Sooty Mold

Sooty Mold

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Sugarcane Aphid Populations Increase

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Our earliest planted milo is booting now where sugarcane aphids were found two weeks prior. Infestations have increased to treatable thresholds. This field is 5 miles south of where SCA were originally found and are 100% infested with aphids covering 30-50% of the plants. This level is very high.

In many fields, I only find aphids in 1 or 2 spots. This makes scouting difficult if we want to catch them early. One thing to look for is shiny or glossy appearance on the leaves (as seen above). This is honeydew which is the sugary-rich liquid excreted from aphids and soft b0died insects. Even in a low infested field, you will see a little bits of a glossy substance on the tip of a leaf. Once you see this, turn it over and inspect for aphids. This is where I have found most of our hits in the field.


Threshold – Several threshold levels are being used in the Delta region for 2015.  One conservative threshold is 25% infested leaves with 50+ aphids per leaf at whorl from preboot stage through dough stage.  In MS, the threshold at pre-boot and boot stages is 20% infested plants with large aphid colonies (100+) and localized areas of heavy honeydew present.  From bloom through dough stage the threshold is 30% infested plants.  I think either of these sets of thresholds will prevent serious yield losses and would suggest using whichever threshold is easiest for you to use.   Once threshold is reach do not delay application because infestations can very quickly go from the threshold level to 100% infested plants and hundreds of aphids per leaf.

Insecticide – PYRETHROID INSECTICIDES ARE NOT EFFECTIVE and may flare infestations by killing all the aphid predators. Regardless of the insecticide, rapidly expanding populations are difficult to control.  Foliar insecticide options for SCA are:

  • Transform WG (Dow AgroSciences) – Transform WG is not fully registered yet, but Georgia, Alabama and several other states haves a section 18 emergency exception approved for 2015 until Nov. 20, 2015. In my insecticide trails last season, rates of 1.0 and 1.5 oz per acre were effective. Use the 1.5 oz rate if aphid populations are increasing rapidly. The label allows for 2 applications per season and not more than 3 oz per acre per crop and has a 14 day PHI.
  • Sivanto (Bayer Crop Protection) – Sivanto has a full section 3 label and a supplemental 2ee label for lower rates on sorghum and other grain crops. The 2ee rates are 4 – 7 fl. oz per acre.  Sivanto was very effective in my trials at rates of 3, 5, and 7 fl. oz. per acre, so the 4 fl. oz. rate should be effective.  At the 4 oz rate it can be applied up to 7 times during the season but has a 21 day PHI.
  • Chlopyrifos (Lorsban Advanced, Nufos, other) – Lorsban is labeled at 1 to 2 pints per acre. The 2 pint rate has a 60 day harvest interval and 1 pint a 30 day harvest interval.  The 2 pint rate was 80-90% effective in my trial last year but could not be used after the boot stage due the 60 day PHI. The 1 pint rate was variable and only partly effective.  DO NOT USE CHLORPYRIFOS ON SWEET SORGHUM.
  • Dimethoate ( Dimethoate, Cygon) – Is labeled up to 1 pint per acre with a 28 day PHI.  Most dimethoate products cannot be used after head emergence. Dimethoate was variable in my trials and not recommended without further testing.

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