By Scout Nelson
NDSU Extension weed specialist Joe Ikley warns of herbicide-resistant kochia, a threat to farmers in North Dakota. In 2022, NDSU scientists confirmed kochia's resistance to PPO-inhibiting herbicides. BASF scientists identified a target-site mutation, leading to the development of a DNA-based test by the National Agricultural Genotyping Center (NAGC) to detect this mutation.
The newly developed DNA test is now open for public submissions of kochia samples. Farmers and researchers can submit samples to detect Group 14 resistance in kochia, along with other resistance tests offered by the NAGC.
These tests include resistance to Group 14 herbicides in waterhemp and Palmer amaranth, as well as Glyphosate (Group 9) and ALS-inhibitors (Group 2) in kochia, waterhemp, and Palmer amaranth.
Sponsored by organizations like the North Dakota Corn Utilization Council, North Dakota Soybean Council, North Dakota Specialty Crop Block Grant, and Minor Crop Utilization Grants, funding is provided for free testing of 1,000 North Dakota pigweed or kochia samples.
The NAGC typically delivers test results within 7 days of sample arrival, with each NDSU Extension County office equipped with testing kits and collection instructions. Once kits are depleted at county offices, farmers can utilize self-mailing instructions and submission forms provided on the NAGC website.
Free testing is currently limited to four samples per farming operation. For additional tests or samples originating from outside North Dakota, charges may apply as per the NAGC's fee structure.
For optimal DNA testing accuracy, farmers should collect leaves from herbicide-surviving plants. This eliminates susceptible plants, enhancing the reliability of resistance determinations.
The NAGC maintains confidentiality regarding individual sample results, sending them directly to the email provided on the submission form, ensuring that county-level data remains undisclosed.
The sampling program, initiated in Fall 2023, has received 51 kochia samples from 21 North Dakota counties. Results indicate significant resistance levels: 33% to Group 14 herbicides, 82% to Glyphosate, and 51% to Group 2 herbicides.
It is crucial to acknowledge the limitations of DNA testing, which can only detect known target-site mutations. Other resistance mechanisms may exist beyond the scope of these tests.
To collect samples for testing, farmers are advised to identify pigweeds or kochia in the field and collect two leaves from each plant. These larger leaves should be placed in a zipper bag or envelope, labeled with a unique Sample ID, and sent to the National Ag Genotyping Center for analysis.
The introduction of rapid DNA testing represents a proactive approach to managing herbicide resistance in weeds, enabling farmers to make informed decisions and safeguard crop yields and sustainability.
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Categories: North Dakota, Crops, General