Being Proactive to Address Diseases in Corn

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In times of unusually wet weather with warm temperatures, and corn is either pollinating or in the milk stage; corn growers should be prepared to be proactive instead of reactive when it comes to making fungicide applications to prevent Southern Corn Rust. Southern Corn Rust can spread at very fast pace, and be potentially devastating to corn yields. When the disease has been identified and is moving throughout the environment, spraying a strobilurins fungicide (Headline, Evito, Quadris etc..) provides ten days to two weeks of protection. The key is to prevent. Thus, primary efforts should include identification of fields most at risk. Scout fields based upon planting date and maturity. If recollection of the approximate date of silking is known, will aid in serving as a reference for targeting the most susceptible fields. If the disease is detected; Triazoles or a combination with strobilurins (Quilt Excel, Trivapro, Stratego, Fortix) assist in alleviating the disease pressure coupled with providing preventative results. However, the percentage of each active ingredient within a product will determine the length of time for control.

Another primary point to consider is that a fungicide treatment will add additional cost to production. Avoiding treatment places emphasis on lack of potential yield loss based upon the assumption that this disease will not spread. Producers need to weigh potential yield, price of corn, production cost, and other factors against pesticide application cost to make a decision that fits personal risk management. Having thus said, assuming a $12/acre aerial application cost + $12 per acre fungicide cost, the breakeven cost at $4/bu of corn means only saving 6 bushels per acre. Assume a yield of 100 bu/ac and a minimum yield loss of 10% and the cost of protective fungicide treatment is a much cheaper option. Assume the same yield with 30% yield loss from Southern Corn Rust and the favorable decision to treat becomes very obvious!

The use of brand names and any mention or listing of commercial products or services in this publication does not imply endorsement by the N.C. Cooperative Extension Service nor discrimination against similar products or services not mentioned. Individuals who use agricultural chemicals are responsible for ensuring that the intended use complies with current regulations and conform to the product label. Be sure to examine a current product label before applying any product.

View a quick visual reference for corn growth stages

Review the current status of Southern rust in the U.S.

Fungicide Efficacy information