Seven states and counting as the dominoes fall. PPO herbicide resistance in Palmer amaranth is spreading in the same manner glyphosate resistance advanced a decade ago. (Good luck finding a Palmer population responsive to glyphosate in some states.) An empty quiver of PPO chemistries (Group 14 herbicides) is no academic footnote; it carries a devastating loss of post-emergence options. Simply, lack of postemergence weapons could mean no soybeans for some farmers.
With alarm bells ringing in Arkansas, Illinois, Indiana, Kentucky, Mississippi, Missouri and Tennessee due to confirmed PPO-resistant Palmer, is the weed control cavalry expected in soybean fields anytime soon? Bolstered by new technologies, help might arrive within five years.
Balance GT. Developed jointly by MS Technologies and Bayer, Balance GT soybeans feature a double herbicide trait stack that provides tolerance to glyphosate and a new isoxaflutole-based herbicide called Balance Bean, which has built-in residual control along with a unique property: reactivation technology.
Balance Bean can be applied as a pre-emergent. According to company officials, benefits of residual control and reactivation technology allow the herbicide to provide long-lasting control. Bayer awaits EPA registration for Balance Bean herbicide.
Eventually Balance GT soybeans will evolve into a triple herbicide trait stack with LibertyLink technology, says Lindsey Seitz, MS Technologies brand manager. “Balance Bean provides great control, especially for PPO- and ALS-resistant weeds,” she adds. “This is a completely new mode of action for soybeans.”
Enlist. Dow AgroSciences hopes to see full commercialization in 2018, once import approvals are obtained, of Enlist soybeans triple stacked with tolerance to new 2,4-D choline, glyphosate and glufosinate. According to Dow, the 2,4-D choline is 88% less volatile than 2,4-D amine formulations and 96% less volatile than 2,4-D ester formulations.
Enlist Duo, the accompanying herbicide, uses Colex-D technology to pack a double-punch of new 2,4-D choline and glyphosate. Dow is also offering Enlist One, a straight-goods 2,4-D choline product. Enlist One is registered in 34 states and can be tank-mixed with glufosinate and other approved tank mix products.
How does Dow expect the Enlist herbicide tolerant traits and new herbicide solution to perform against PPO-resistant Palmer? “Enlist Duo uses two of the most trusted herbicides combined to deliver exceptional control against resistant and hard-to-control weeds,” says John Chase, Enlist commercial leader. “It provides control of major, tough weed species.”
MGI. Many growers have turned toward glufosinate to avoid glyphosate dependence. However, glufosinate can be trickier to use on Palmer, due to the need for timely applications, and results in an emphasis on a residual program.
The MGI system will raise the bar on residual control in soybeans, says Duane Martin, commercial traits manager for Syngenta. “MGI will provide corn class weed control up front with pre-emergence products to accompany the system, followed by a well-timed postemergence application of a herbicide such as glufosinate, depending on weed pressure,” he says.
Currently under regulatory review, MGI trial sites are set up for viewing and Martin anticipates introduction by 2020 or earlier. Mesotrione and isoxaflutole are HPPD products, and Martin expects MGI to raise the bar for broadleaf control in soybeans.
“MGI provides multiple technologies on an acre with overlapping modes of action. These are critical factors in controlling resistant weeds,” he adds.
Sumitomo. In June 2016, Monsanto and Sumitomo Chemical announced a collaboration to develop an integrated weed control system based on a Sumitomo PPO herbicide for over-the-top and conventional application use. The PPO herbicide will not be available until after 2020.
“The product’s low use rate, together with a unique mode of action effective against resistant PPO weeds, will be valuable to corn, soy and cotton growers,” said Robb Fraley, Monsanto executive vice president and chief technology officer, in an announcement.
Change Of Attack. “Simplicity has got us to the resistance situation we’re in, but chemical mixes and stacked traits provide multiple options that will definitely help in battling resistant Palmer,” notes Jason Norsworthy, an Extension weed scientist at the University of Arkansas.
However, Norsworthy is quick to warn against sole reliance on chemical solutions.
Norsworthy cites two Australian equipment innovations as examples of potential non-chemical weapons against Palmer and other resistant weeds. The Seed Terminator (ST) is a combine addition that intercepts and pulverizes seed as it exits the cleaning shoe through multi-stage hammer mill technology. ST prototypes are on a variety of combines in Australia, including John Deere, Case IH and New Holland. ST is testing prototypes in the U.S. this fall.
A related technology to the ST, the Harrington Seed Destructor (HSD) is a seed pulverizing machine relies on a cage mill apparatus. The same technology used in the mining industry is unleashed on weed seed. Two counter-rotating mills spin at more than 3,000 rpm and fracture passing weed seed when funneled chaff hits the crossbars at a super-high speed. The steel-on-seed-battering cycle is effective and requires no chopping or mashing.
Built by de Bruin, an Australian manufacturing firm, the iHSD has no U.S. market entry date, but company officials say it could see limited release in 2019.