Tips for Summer Corn Scouting

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Corn scouting

No matter when your customers were able to get into the field for planting this spring, regular scouting can help set the stage for a successful corn yield come harvest. 

Getting into the field on a regular basis after planting will improve the timing on important crop protection decisions. Is there a new flush of weeds that needs to be managed? Will postemergence herbicides need to be applied sooner than anticipated? Are there any nutrient deficiencies? Are there any new insect or disease pressures? All these questions can be answered and addressed with regular scouting.

Scouting should occur multiple times throughout the growing season, but there are times when it’s more critical, says Joe Bolte, market development specialist, Corteva Agriscience.

Key Corn Scouting Timing

  • After plant emergence, to evaluate the stand and ensure a replant is not needed. 
  • After preemergence applications, to evaluate the herbicide program. How well are preemergence or residual applications holding? Is the field clean? Early-season scouting can help determine if customers will need to apply postemergence herbicides earlier to reduce weeds during the critical weed-free period.
  • After postemergence applications. This is the time to take detailed notes on any weed escapes to improve next year’s weed control program. 
  • Midseason, and at least every two weeks until harvest to check for weeds, insects and disease pressure. As harvest nears, it’s important to also evaluate stalk and grain quality.
  • Harvest. This is another good time to assess weed and disease challenges to improve management practices for next season.

Pests to Watch This Year 

With lengthy emergence periods, waterhemp and Palmer amaranth present an annual challenge — calling for a herbicide program approach that includes multiple modes of action for effective control. Bolte says these weeds may be even harder to control this year.

“In many areas, growing degree unit calculations ran ahead of schedule compared to normal years, causing earlier germination of pigweeds. Depending on your geography and planting date, waterhemp or Palmer amaranth may need to be controlled in every herbicide pass — not just the postemergence application.” 

On the flip side, your customers in areas with heavy rainfall may not have had a chance to get their preemergence herbicides down in time. If this is the case, they may consider reallocating those preemergence herbicide dollars to create a more powerful postemergence pass. 

Bolte also says that tar spot should be on everyone’s radar this year, as this disease continues to spread to new fields. Scouting the corn plant’s canopy will help determine if a fungicide application is warranted.

Scouting Resources Available

There are several free resources available to help customers with in-field corn scouting. “Many universities will put together scouting guides or calendars for common pests. Use these to determine when weeds, disease and insects are most likely to emerge in your geography,” Bolte says.

You also can contact your local Corteva Agriscience representative and download our Corn & Soybean Disease ID Guide and Corn Weed Scouting Checklist for more detailed information. 


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