Managing Tough Weeds with Enlist and Extend Weed Control Systems Tom Peters Extension Sugarbeet Agronomist North Dakota State University and the University of Minnesota

Waterhemp in soybean, 2014 Renville County, MN

Waterhemp, an assessment by county Waterhemp in 2015

Waterhemp in 2015 Walsh County Polk County, Euclid, MN SR 200, Norman, County Traill County

Common Ragweed Kochia More problematic with increase in soybean and dry bean acres Germinates in the spring but returns to dormancy when temperatures get hot in June and July Germination at our near the soil surface Control when three inches or less Resistant biotypes to multiple classes of herbicides ALS (SOA 2) PPO inhibitor (SOA 14) Glyphosate (9) Extremely competitive weed; a few plants can cause yield reduction Many document examples of herbicide resistance 2,4-D and MCPA (SOA 4) ALS (SOA 2) Glyphosate (SOA 9) Control in the crop sequence, small grains and corn In sugarbeet, control POST when kochia is small Kochia seeds loose viability after one or two years

Enlist or Xtend soybeans will be arriving soon How will the system perform on tough-to-control/ resistant weeds in YOUR FIELDS? 2,4-D dicamba Kochia N/P E Common ragweed Waterhemp F F/G Marestail Palmer amaranth Scale: E = Excellent = 90 to 99% G = Good = 80 to 90% F = Fair = 65 to 80% P = Poor = 40 to 65% N = No Control A product of a conversation with Dr. Richard Zollinger, NDSU Weed Science

2,4-D Herbicide Synthetic auxin herbicide in the phenoxy chemical family First used in the U.S. in the 1940s and marked the beginning of the selective chemical weed control era One of the most widely used herbicides worldwide Controls annual and perennial broadleaf weeds in grass crops Would offer a different mode of action for control of tough-to-control broadleaf weeds in soybean Slide credit: Dr. Jim Griffin, Louisiana State University

Dicamba Herbicide Synthetic auxin herbicide in the benzoic acid chemical family Discovered in 1958 and first marketed in 1964 as Banvel DMA salt Clarity DGA salt marketed in 1992 Sixth most widely used herbicide in the U.S., with more than 25 million acres of farmland treated annually Controls annual and perennial broadleaf weeds in grass crops Would offer a different mode of action for control of tough-to-control broadleaf weeds in soybean Slide credit: Dr. Jim Griffin, Louisiana State University

Enlist Weed Control System 2,4-D Tolerant Crops (Dow AgroSciences) Crop tolerance in transgenic plants achieved through insertion of the aad-12 gene that encodes for a bacterial aryloxyalkanoate dioxygenase enzyme (metabolism/deactivation gene) Production of enzyme leads to breakdown of 2,4-D to the non-herbicidal dichlorophenol. In corn, the enzyme will also lead to the breakdown of the ayloxyphenoxy propionate (fop) herbicides: fluazifop (Fusilade), quizalofop (Assure) H 2,4-D acid dichlorophenol ____________________________________________________________________ phenoxy Slide credit: Dr. Jim Griffin, Louisiana State University Fusilade (fluazifop)

Roundup Ready Xtend Crop System Dicamba Tolerant Crops (Monsanto) Discovery at University of Nebraska of soil bacterium (Pseudomonas maltophilia) that metabolizes dicamba to a non-herbicidal/inactive form (Science 2007) Crop tolerance in transgenic plants achieved through insertion of a gene that encodes for a bacterial DMO (dicamba monooxygenase) enzyme (metabolism/deactivation gene) Production of DMO leads to breakdown of dicamba to the non-herbicidal 3,6-dichlorosalicylic acid Slide credit: Dr. Jim Griffin, Weed Scientist, LSU H 3,6-dichloro-o-anisic acid (dicamba acid) 3,6-dichlorosalicylic acid (non-herbicidal)

Available Sites of Action By Crop Site of Action (SOA number) Corn PRE Corn POST Soybean PRE Soybean POST 2 4 3 [9] 5 [10] 15 (ePOST) 14 27 Reliance on a single SOA across crops/years increases the likelihood of resistance Generational differences in weeds from season to season [ ] = GMO Slide developed in collaboration with Dr. Mike Christoffers

Concerns/Issues Dicamba and 2,4-D Technologies Labels will be very specific and restrictive Crop sensitivity 2,4-D on sugarbeet and dicamba on soybeans Like Brylcreem, “a little dab’ll do ya!” These herbicides “will tell on you!” Off-target movement Volatility not likely to be major contributor; companies have developed “low volatile” formulations Physical drift – affected by droplet size, spray pressure, nozzle type, boom height, wind speed, etc. Spray tank contamination/sprayer clean-out Slide credit: Dr. Jim Griffin,Weed Scientist, LSU

Summary Enlist and Extend require EPA approval and China grain import approval before they will be available for sale Dow AgroSciences and Monsanto are preparing for launch Both technologies will require use of spray nozzles that produce a large droplet spectrum Both technologies have a much more restrictive label than past new products Prevention of particle drift to susceptible non target plants will be an important management strategy

Thank you for your Attention and your Support Tom Peters Extension Sugarbeet Agronomist and Weed Control Specialist Thomas.j.peters@ndsu.edu Thomas Peters @tompeters8131 701-231-8131 (office) 218-790-8131 (mobile)