Pennsylvania: Corn, Soybean Weed Control – What’s New for 2019

Escaped waterhemp in soybeans. Photo: University of Missouri

Escaped waterhemp in soybeans. Photo: University of Missouri

As in the recent past, there are absolutely no new herbicide modes of action. All the newer herbicide products are simply new premixes or revised formulations of existing active ingredients.


Coyote 3.67SE (mesotrione [Callisto] + s-metolachlor [Dual II Magnum]; groups 27 and 15 herbicides; UPL) and Harness MAX 3.82SE (mesotrione [Callisto] + acetochlor [Harness]; groups 27 and 15 herbicides; Monsanto) are comparable product premixes and will serve a similar utility.

These will primarily be used post in field corn to provide some foliar and extended residual activity on annual broadleaves, especially for weeds like Palmer amaranth and waterhemp, and some residual activity on annual grasses. Neither of these are effective on existing grasses, so they will likely be tank-mixed with glyphosate or other effective herbicides.

Shieldex 3.33SC (tolpyralate; group 27; SummitAgro) is a new, low use rate (1 to 1.35 fl oz/A), HPPD-herbicide that controls annual grasses and broadleaves postemergence in field and sweet corn. It is very similar to Armezon or Impact.


Authority Supreme 4.17L (sulfentrazone [Spartan] + pyroxasulfone [Zidua]; groups 14 and 15; FMC) is registered for use in soybean. It will be soil-applied and have activity on both annual grasses and broadleaf weeds.

Flumioxazin (Valor) is a popular active ingredient in many soybean herbicides today. It will also be in three newer products, Fierce MTZ, Panther Pro, and Valor EZ, which are available.

Fierce MTZ 2.64SC (flumioxazin [Valor], pyroxasulfone [Zidua], and metribuzin; groups 14, 15, and 5; Valent) is a soil-applied premix herbicide for control of many annual weeds.

Panther Pro 4.23L (flumioxazin [Valor], imazethapyr [Pursuit], and metribuzin; groups 14, 2, and 5; Nufarm) also is a pre herbicide premix that controls many different types of annuals.

Valor EZ 4SC (flumioxazin [Valor]; group 14; Valent) is a new liquid formulation of flumioxazin and will have the same utility as the dry form and primarily controls broadleaf weeds including marestail and Palmer amaranth.

Corn and Soybean

Elevore 0.57SC (halauxifen; group 4; Corteva), sometimes referred to as Arylex active, will be primarily used in burndown programs. It is a new plant growth regulator herbicide similar to 2,4-D and dicamba but is not a new mode of action. Elevore has better activity on marestail than 2,4-D but is similar to dicamba. Otherwise, it has a limited control spectrum so it will need to be tank-mixed with other burndown herbicides. One of the main use issues is that it must be applied 14 days before planting for soybean or corn which may limit its utility.

EverpreX 7.62E (s-metolachlor [Dual Magnum]; group 15; Corteva) is a single active ingredient of s-metolachlor and will likely be tank-mixed with glyphosate and other herbicides for residual control of Palmer amaranth, watherhemp, and several other weeds in conventional or Xtend soybeans. It can also be used in corn and several other crops.

Gramoxone Magnum 3.33EW (paraquat [Gramoxone] + s-metolachlor [Dual Magnum]; groups 22 and 15; Syngenta) provides burndown of many weeds and residual control of annual grasses, some small-seeded broadleaves, and nutsedge. It can be used in soybean, corn, and other crops. (This formulation does not contain the corn safener for Dual.) It is expected to be available for the 2019 growing season.

Zidua SC 4.17L (pyroxasulfone only; group 15; BASF) is simply a liquid formulation of pyroxasulfone and will have the same use as the dry formulation and it controls many annual grasses and broadleaves.

Soybean Technologies Updates

Roundup Ready 2 Xtend soybean

The EPA has re-registered the Xtend-specific dicamba products until Dec. 2020. Engenia 5L(dicamba-BAPMA salt; BASF), Xtendimax 2.9L (dicamba-DGA with Vapor Grip Technology; Bayer) and FeXapan 2.9L (dicamba-DGA plus Vapor Grip Technology; Corteva) are currently the only three dicamba herbicides that can be used in Roundup Ready 2 Xtend (dicamba-tolerant) soybeans.

Each of them contain the group 4 herbicide dicamba and are now classified as “Restricted Use Pesticide” (RUP) and thus require special dicamba-specific training annually to purchase and apply them. In addition to the existing label guidelines, some additional label changes have been made for 2019.

Engenia Pro 4.5SC (dicamba + pyroxasulfone [Zidua]; groups 4 and 15; BASF) and Tavium 3.39CS (dicamba + s-metolachlor [Dual Magnum]; groups 4 and 15; Syngenta) are experimental premixes and will provide post broadleaf control from dicamba and residual annual grass and broadleaf control from Dual/Zidua in Xtend soybeans. Their prime targets will be Palmer amaranth and waterhemp. These may receive registration for use in 2019.

Xtend soybean acres: During the 2018 growing season, there were approximately 90 million acres of total soybeans planted in the US.; about 40 million or so acres were Xtend. In some areas of the country up to 75% of the soybean areas were planted to an Xtend variety.

The exact amount of acres that actually applied either a pre or post application of dicamba is not known, however in most areas it was a rather large percentage. In Pennsylvania, there were about 595,000 acres of soybeans planted in the state of those about 25% were Xtend. A good majority of them were sprayed with dicamba by private applicators. Many commercial applicators did not apply dicamba to Xtend soybeans this past season for various reasons.

Expectations for the 2019 growing season are that the acres of Xtend soybeans will continue to expand to about 50 million acres across the country. However, some have decided not to grow Xtend soybeans for various reasons and have opted to stay with typical Roundup Ready varieties, other may plant LibertyLink lines that allow for better post control of marestail and Palmer, and finally some may even try non-GMO lines since they can usually get a price premium.

Incoming soybean technologies

The next generation of Xtend technology is referred to at HT3 soybeans which will be resistant to dicamba, glyphosate, and glufosinate (Liberty). These varieties, which will be a part of the XtendFlex brand, are not yet registered but are expected to be launched in 2020.

LibertyLink soybeans have been registered for several years and more varieties are available. LibertyLink GT27 soybean is the next generation of stacked trait varieties that are resistant to glufosinate, glyphosate, and isoxaflutole, an HPPD herbicide which will be called Alite27 (like Balance herbicide). These soybeans should be available in 2020.

Enlist soybeans (2,4-D tolerant) was recently approved for export to China. It is not known yet if Enlist soybeans will be available for the 2019 growing season. But since this is an ever-changing process, things could happen at any time.

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