Agronomy Library

Managing Diseases in Late-planted Crops

Titan Pro
July 9, 2024

*This content was previously published by Corteva Agriscience.

Late-planted crops are generally more susceptible to crop disease. The reason is due to the “disease triangle.” Diseases thrive when all three pieces of the disease triangle coexist — a favorable host, the pathogen and the right environment. Planting dates won’t affect the pathogen or the environment — but later planting can affect the growth stage and susceptibility of the plant host during the time of significant disease pressure.

“In diseases that result from pathogens overwintering in residue, delayed planting allows more time for disease pressure to build up in earlier growth stages,” says Scott Pringnitz, Market Development Specialist, Corteva Agriscience. Examples of diseases that overwinter include tar spot, white mold, gray leaf spot, eye spot, frogeye leaf spot and northern corn leaf blight.

“Similarly, diseases that result from spores that don’t overwinter, such as common rust or southern rust, generally have more time to move from southern to northern climates during susceptible growth stages,” Pringnitz says.

To help customers stay ahead of crop disease, Pringnitz emphasizes the importance of staying informed and being proactive.

“There are several third-party resources and crop protection manufacturers that track environmental conditions that favor disease development. By staying informed, you can encourage customers to be scouting their fields or make fungicide applications before disease greatly impacts yield.”

Fungicide Timing and Product Choice Matter

Most fungicides are very effective for a two-to-three-week period. Timely applications can maximize the value of the application and reduce the need for additional applications. “Fungicides are unable to reverse crop damage or yield impact,” Pringnitz says. “If customers wait too long to apply fungicides, they simply will not see the same return on investment that a well-timed application can provide.”

When it comes to choosing a fungicide, growers should review product information for the specific diseases controlled to make sure it matches their disease pressure. For example, Corteva’s Aproach® fungicide is labeled for all of the diseases mentioned above.


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