2008 Year in Review

From the Fields

The application of foliar fungicides to corn was a “hot topic” in 2007 and continues to be one for 2008. This topic was addressed, by several speakers from the Midwest, at the recent Illinois Crop Protection Technology Conference “Hard and fast” fungicide guidelines do not exist for corn, however, application decisions can be made in part based on risk factors according to Carl Bradley, University of Illinois Extension plant pathologist. Pre-plant risk factors include the amount of corn residue on the soil surface, planting date, and hybrid resistance.

Post-planting risk factors are weather (rainfall and relative humidity) and crop scouting observations.

Bradley noted that based on University of Illinois corn fungicide trials conducted in 2007, “automatic” significant yield increases with foliar fungicides did not occur. Even though the fungicides had good efficacy against gray leaf spot, a reduction in disease severity did not always translate into a yield benefit. This could be due to the fact that almost every trial in 2007 had low disease pressure and never reached the level that could cause economic yield losses.

Bradley concluded encouraging the use of the above-mentioned pre-planting and post-planting risk factors to make fungicide application decisions to increase the profitability and reduce unwarranted fungicide applications.

Fungicide application to corn was generally effective in reducing incidence of foliar disease where it occurred, noted Emerson Nafziger, University of Illinois Extension crop specialist.

In eight of ten trials he conducted across Illinois in 2007, there was either no yield increase or, if one existed, it was inadequate to pay for the treatment. In the two trials where yield was increased enough to produce a profit from fungicide application, one was corn following corn and one was corn following soybean. On average, application of fungicide over these ten trials increased yield by 3 bushels per acre, only half enough to pay for the treatment.

These results show that, in a year when there was little foliar disease at the time of fungicide application and when conditions are such that diseases do not become a major factor, the use of foliar fungicide seldom returned its cost concluded Nafziger.

by  Editor, theCity1.com
January 18, 2008