Crop Production

Doniphan Co Agricultural Extension Newsletters are emailed out every other month. Check out past editions:

February 2025 | December 2024 | September 2024 | July 2024

Doniphan County Corn Variety Plot Results:

Doniphan County Corn Variety Plot Results - 2024

Corn Stunt Disease Resources

Low levels of corn stunt disease have been confirmed in Kansas - K-State Research and Extension

Corn Leafhopper Leads to Corn Stunt Disease Across Oklahoma – Oklahoma State Extension

Soybean Gall Midge

In 2023, soybean gall midge was found infesting soybean and sweet clover in Marshall and Nemaha counties. It has been found in Nebraska and Missouri counties bordering Kansas. This pest causes complete lodging of soybean, sweet clover, alfalfa stands starting at the edges of fields working towards the inner part of the field. For more info please check out this K-State Extension source - Keep an eye out for Soybean Gall Midge.

Gray Leaf Spot in Corn

In 2025, Gray Leaf Spot was found in fields along the Jackson and Atchison county lines. Please scout for this disease now in the 2-3 weeks before corn tasseling. Please check out this publication MF2341 from K-State Extension.

Tar Spot Fungus in Corn

How do I scout for Tar Spot?

Tar spot develops as small, black, raised spots (circular or oval) that develop on infected plants and may appear on one or both sides of the leaves, leaf sheaths, and husks. Spots may be found on healthy (green) and dying (brown) tissue. Tar spot can be easily confused with insect droppings, which can appear as black spots on the surface of the leaf. Use a damp cloth to wipe the leaf to determine if you have presence of a disease lesion.

K-State Extension Specialists are asking producers to look at the bottom up in the canopy, and you should be able to determine if you have it. Please continue to scout for this disease if you've had tar spot previously or neighbors have. Tar spot lives on in the residue. (June 2025)

How do I identify and diagnose Tar Spot on my corn?

Please contact or visit the Doniphan County Extension office! We will assist you to send photos of corn with suspected tar spot to be diagnosed for no charge by the K-State Plant Disease Diagnostic Lab or our Area Extension Agronomist.

More information on corn Tar Spot can be found below:

Low levels of Tar Spot have been confirmed in Kansas - June 11th, 2025 Low levels of tar spot was first confirmed for 2025 corn crop year in Doniphan County.

Tar Spot in Corn IPM Tracker - CornIPM Pipe Map of US Tar Spot scouting.

Fungicide Efficacy for Control of Corn Foliar Diseases - Crop Protection Network has the most up to date research and recommendations for Tar Spot.

Private Certified Pesticide Applicators

Private certification may be obtained by passing an open book examination at the Doniphan County Extension Office. Contact the office in advance to ensure the office will be open and allow 2-3 hours to complete the examination. We will collect the $25 fee and mail the completed examination to KDA for grading and issuing the certification card. Private applicator certification expires on the individual's birthday in the 5th calendar year after it is issued. - This will be changing after 2025 with 3 new options, with one being a closed book examination taken at the Extension office. We are awaiting on the KDA's final decision.

We also have manuals available for sale.

Soil Testing

Prior to conducting a soil test, please contact the Doniphan County Extension Office. Depending on the issue, a photos of the issue can be used to determine if plant diagnostics and/or soil testing is necessary.

Development of sound nutrient management programs involves knowledge of a wide range of information. Soil test records are an important piece of required information, but other factors such as soil moisture conditions, land ownership/tenure, crop and cropping sequence, pest management, cultural practices, environmental issues, and other management items are vital for developing sound nutrient management programs.

K-State Research and Extension offers soil testing through the K-State Soil Testing Lab in Manhattan. Samples may be submitted through the local extension office. Most often, soil tests are taken in the spring before planting, or the fall after harvest.

Proper soil sampling technique

  • Supplies: clean bucket or pail, soil probe (available from the extension office), clean small plastic containers or plastic bags.
  • Sample each field or management area separately, and try to sample from representative sites within the field - avoid fencerows, high-traffic areas, wet or low spots, or any area that doesn't reflect the "average" of the field. Aim to take 20-30 cores total (may be smaller in small fields). Each core should not represent more than about 5-10 acres, depending on the uniformity of the field.
  • Sample to the proper depth:
    • 6 inches for most basic soil tests for row crops
      • Split samples of 0-3 and 3-6 inches for no-till
    • 4 inches for permanent sod
    • 24 inches for available nitrogen, chloride, or sulphur
  • Combine all cores in a clean bucket, mix well, and take a subsample (about 2 cups). Store in a clean plastic container or bag. Allow the sample to dry out if it is wet and/or you will not be able to get it to the extension office promptly. Label the container with the field, date, and depth of the sample.
  • Bring all samples to the extension office with this additional information:
    • Field ID
    • Test(s) desired
    • Previous crop and intended next crop
    • Yield average
    • Tillage method and irrigation use
  • Extension office staff will provide you with forms (or you may download and print them yourself) and help calculate the total cost. Samples may take a week or two to be analyzed, so plan in advance. Results and recommendations will be made available to you after that.

Resources Available

Helpful Crop Links

Helpful Farm Management Links