Proper disease management is critical to preserving corn yields. If not properly managed, diseases can be a major yield-limiting factor.
The first line of defense for managing corn diseases is genetic resistance. Pioneer rates its hybrids for resistance relative to known susceptible and resistant hybrids using a 1 to 9 rating system (1 = susceptible, 9 = resistant). These scores are made available to customers to aid in hybrid selection.
Foliar fungicides are an important management option for fungal diseases. Over the course of 5 years, Pioneer researchers conducted 587 on-farm fungicide trials comparing yield of untreated corn to corn treated with a foliar fungicide between tasseling and brown silk. Across these trials, the average yield response to fungicide application was an increase of 6.7 bu/acre (Figure 2).
One of the most important factors in determining the value of a foliar fungicide application is disease pressure. For example, in a 2009 Pioneer research trial, yield response to a fungicide application was impacted by common rust. Across locations where common rust was prevalent, yield response averaged 11.4 bu/acre whereas at locations where common rust was less prevalent yield response averaged 3.9 bu/acre (Figure 3).
Disease pressure is generally lower under drought conditions because common foliar diseases favor moisture and humidity to develop and spread.
When comparing foliar fungicide trials conducted in Iowa and Missouri in 2011 and 2012 (both abnormally dry years) to trials done in prior years, drought conditions were shown to reduce the average yield response to foliar fungicide application (Figure 4).
Hybrid and variety responses are variable and subject to any number of environmental, disease and pest pressures. Individual results may vary.
The foregoing is provided for informational use only. Please contact your Pioneer sales professional for information and management suggestions specific to your operation.