2008 Year in Review

From the Fields

A record number of Illinois corn acres were sprayed with foliar fungicides in 2007. A similar trend is expected for this year, according to Dr. Carl Bradley, University of Illinois Extension plant pathologist.

Foliar fungicides did not provide a benefit to corn every time they were applied in 2007. So, under what conditions will a foliar fungicide applied to corn be profitable?

Bradley suggests determining the cornfield’s risk of developing foliar diseases is a strategy that can help make a fungicide application decision. Risk factors are discussed below.

Previous crop and tillage practice - When corn was the previous crop and a substantial amount of the residue is left on the soil surface, the risk of foliar diseases increases.

Planting date - Research data has indicated that late-planted corn is more at risk to gray leaf spot than early-planted corn.

Hybrid susceptibility - Most hybrids are rated for their susceptibility to diseases like gray leaf spot and northern corn leaf blight. When hybrids with greater susceptibility to these diseases are planted, the risk of the diseases increases.

Weather and environment - High relative humidity and moisture favor development of foliar diseases on corn. Disease observations - Scouting fields prior to tassel emergence may give an indication of potential disease pressure. By scouting one can observe how quickly diseases are building on the lower leaves. Bradley suggests using the following fungicide guidelines based on scouting observations.

- For susceptible or moderately susceptible hybrids, a fungicide application should be considered if the disease is present on the 3rd leaf below the ear or higher on 50 percent of the plants before tasseling.

- For intermediate hybrids, fungicide application should be considered if conditions and factors are favorable for disease and if the disease is present on the 3rd leaf below the ear or higher on 50 percent of the plants before tasseling.

- For resistant hybrids, a fungicide application is generally not recommended, but field scouting is still important.

In summary, Bradley notes that foliar fungicides can help increase production and profits, if they are used appropriately. Be sure to read and follow the label before using any pesticide.

by  Editor, theCity1.com
July 31, 2008