Late-planted cornfields, often due to unfavorable spring weather, face challenges that can impact crop development and increase vulnerability to pests and diseases. These challenges can make the crop vulnerable to yield loss since they can affect the crop at earlier stages of grain fill. Stalk borers can emerge as a significant threat, jeopardizing yield potential.

What you should know:

Late planting changes the growth cycle of corn, making it more susceptible to pests and diseases during critical growth stages. Key pests include Corn Rootworm, Corn Earworm, European Corn Borer, and Fall Armyworm. These pests attack different parts of the plant, ranging from roots to ears, leading to significant yield loss. Corn Rootworm damages roots, impacting the plant’s water and nutrient uptake. The Corn Earworm prefers warm, humid nights and can be particularly destructive, laying eggs on silks and having larvae that feed down the ear.

Diseases also pose a significant risk to late-planted corn. Southern Rust, Northern Corn Leaf Blight, Stalk Rots, Gray Leaf Spot, Southern Corn Leaf Blight, and Tar Spot are notable threats. These diseases, mostly fungal, flourish under specific temperature and humidity conditions and can rapidly damage large crop areas.

What you can do:

1. Choose resistant hybrids: Opt for AgVenture brand Qrome® corn hybrids or the newly released Vorceed® Enlist® corn hybrids (check with your local AgVenture ISC to check availability!) with built-in resistance or tolerance to specific pests such as Bt corn hybrids. Ensure compatibility by checking labels and adhering to refuge requirements to prevent resistance development.

2. Integrated Pest Management (IPM): Combine biological, cultural, and chemical methods to manage pests and diseases effectively. This includes crop rotation, resistant varieties, and targeted pesticide use.

3. Soil and Crop Health: Maintain soil health and provide adequate nutrients to enhance the plant’s natural defenses.

4. Scout Fields Early and Often: Increase the frequency of field scouting with your AgVenture Yield Specialist to identify signs of stalk borer infestations. Focus on late-planted fields, paying close attention to leaves, midribs, and stalks for damage symptoms.
   • Rootworm: Monitor late-planted fields for larvae feeding on root hairs and outer root tissue. Be proactive in corn stress caused by rootworm feeding during pollination.
   • Corn Earworm: Stay vigilant during warm and humid nights for CEW activity. Regularly inspect silks for egg-laying and larvae feeding down the ear.
   • Fall Armyworm: Be aware of late-stage fall armyworm larvae that can defoliate corn, particularly in fields with reduced tillage. Consider management strategies, especially in areas with grassy weeds.
   • European Corn Borer: Attacks corn starting in early June and can last until late July – early August. First generation larvae cause damage to the leaf surface and bore into the midrib before making their way to the stalk.

5. Timely Intervention: If pests or diseases are detected, take prompt action to reduce damage. This could involve applying insecticides or fungicides, depending on the specific threat.

Tailor your strategies

Late-planted cornfields face increased risks from stalk borers and a host of other pests and diseases. Vigilant scouting, integrated pest management, and proactive disease control measures are essential for reducing these risks. Talk with a local AgVenture Yield Specialist or agronomist to tailor your strategies to protect your corn crops during the critical stages of growth.

References:

Stalk Borers Bulletin, Purdue University Cooperative Extension Service
https://ag.purdue.edu/department/entm/extension/field-crops-ipm/corn/stalk-borers.html