April 21, 2009
A foliar fungicide application can boost yields in corn affected by the gray leaf spot disease, according to a new research conducted by Pioneer Hi-Bred and the University of Tennessee.
The three-year study shows the impact of foliar fungicide applications on susceptible, moderately susceptible and tolerant gray leaf spot corn hybrids.
Gray leaf spot is a common foliar disease on corn fields where high residue and ample moisture or irrigation is present, and has the potential to greatly reduce yields.
The study sowed increased yields with a foliar fungicide application for all three types of hybrids tested in the study, with the largest boost being 24 bushels per acre with the susceptible hybrid.
The study used Headline and Quadris fungicides for the application. Compared to unsprayed fields of the same hybrids, the susceptible hybrids increased 23.5 bushels per acre on average, the moderately susceptible hybrids averaged 12.5 bushels per acre, while the tolerant hybrids averaged an increase of seven bushels per acre.
This suggests that hybrids with gray leaf spot tolerance provide an effective avenue for growers in areas where the disease is a concern, said Greg Luce, agronomy services manager for Pioneer.
Depending on commodity prices, the study suggests spraying tolerant hybrids in a heavy disease environment can be a viable practice for growers, Luce said.
Application timing is vital when using a foliar fungicide. Application should occur at full tassel, as research has showed that applications prior to tassel can have negative effects and can even reduce yields.
Weather is also a key factor. If moisture continues following tassel, a grower should consider spraying. If there is minimal moisture following tassel, disease development is often slowed sharply and a foliar fungicide application may not be needed.
When looking to use a foliar fungicide application during the growing season, producers should know the susceptibility rating of the hybrid, factors that can increase potential for the disease, and the weather environment, said Melvin Newman, field crops plant pathology specialist at the University of Tennessee.