Rare Winter Wheat Pest Infestation Could Drive Up Pesticide Costs

An unusually heavy infestation of fall armyworms in US winter wheat growing regions could push growers’ pesticide costs higher this season. 

The fall armyworm (FAW) is the larval stage of the fall armyworm moth and is one of the most pervasive and destructive pests to agricultural crops. Gro developed a Fall Armyworm Arrival and Risk Model Framework in response to the spread of FAWs across Asia starting in late 2018. The framework uses inputs such as weather and occurrence data to assess risk and identify when fall armyworms will arrive. 

Roughly a quarter of the winter wheat crop is already planted, and fall armyworms (FAW) could wreak havoc with the plants as they break ground. Southern growing states are seeing greater than normal concentrations of FAWs, and more northerly states are experiencing a rare invasion after recent hurricanes drove the pests farther north. 

Chemical inputs, including pesticides, typically account for about 12% of US wheat growers’ operating costs, Gro's Crop Budget App shows. Those costs could run higher this year as farmers battle to control the FAW infestation. Growers also might not be prepared with the correct pesticides to fight FAWs, especially in northern areas where the pests aren’t usually a major problem. 

High wheat prices are encouraging farmers to plant as much as possible. Wheat supplies are at their tightest levels in eight years, and Chicago and Kansas City wheat futures contract prices have risen to seven-year highs. 

Rather than applying more pesticides, some growers might choose to delay further wheat planting until the FAW infestation has subsided. However, this runs the risk of frost damage if the wheat doesn't grow enough before entering dormancy. And studies have shown that delays beyond the optimal planting date lead to progressively greater declines in winter wheat yields.

FAWs thrive in temperatures between 77-86 degrees F (25-30 degrees C). Lower temperatures slow the pests’ growth and could make them easier to control. Only a hard frost will kill off the FAWs. 

For example, temperatures in Harper County, Kansas, a major region for hard red winter wheat, currently range from a high of about 80 degrees to a low of 60 degrees. Gro’s GFS forecast models, as displayed in the Gro Navigator for Agriculture app, show the temperature range dipping to 70-50 degrees by Oct. 9.

FAWs’ life cycle ranges from 30 to 90 days, with higher temperatures encouraging faster insect growth. The larvae or caterpillars hatch a few days after eggs are laid, which is when they feed on crops and cause the most damage. Adult moths have a strong migratory ability, traveling over a half a mile a day, and planting eggs several times. 

To learn more about fall armyworms, their impact on supply chains globally, and how to model for FAW risk, download Gro’s Strategic Assessment: “Managing Climate Risk for Plant Pests and Diseases.” And contact us at support@gro-intelligence.com. 

This insight was powered by the Gro platform, which enables better and faster decisions about factors affecting the entire global agricultural ecosystem. Gro organizes over 40,000 datasets from sources around the world into a unified ontology, which allows users to derive valuable insights such as this one. You can explore the data available on Gro with a free account, or please get in touch if you would like to learn more about a specific crop, region, or business issue.