Currently, it is 100+ degrees and western Iowa has received very little rain. These weather conditions have caused crops to pollinate rapidly, which means growers are beginning to consider spraying a foliar fungicide.

Actively scouting fields is an important step in the decision-making process about whether to spray a foliar fungicide. Diseases are beginning to show and western Iowa has started to see Common Rust and Grey Leaf Spot in corn and Brown Stem Rot and Bacterial Leaf Blight in soybeans. So, does this mean you should you spray a fungicide?

Remember, a fungicide will not have any impact on bacterial diseases. As corn begins tasseling and soybeans flowering, consider the topics from Integrated Pest Management below before applying a fungicide.

1. Hybrid or variety susceptibility
2. Amount of residue (corn-on-corn or corn following soybeans)
3. Planting Date (huge this year)
4. Yield potential
5. Cost of application (my area averages $27 - $30/acre aerial sprayed)
6. Grain market value

Another consideration must be economics. Corn is hovering just over $4.40 and soybeans is above $8.60/bushel. The ability to have an acceptable ROI from a fungicide application needs to be considered. The breakeven to cover cost on corn is about 6-7 bushels on corn and 3-4 bushels on soybeans, given today’s market. If you do the math it is quite simple: foliar fungicides can pay for themselves when there is disease present.

With all this said, I have scouted extensively looking for any diseases and have been able to find limited infestations of a variety of diseases. Based on the low number of planes that have been flying, I would expect others are finding the same results.

LG Seeds has made fungicide response of corn hybrids available here. Remember that some hybrids can show a strong fungicide response in yield and harvest appearance when disease is present. Fungicides with multiple modes of action are most beneficial in the high yield environment, especially under heavy disease pressure. Fungicides also improve staygreen and harvest intactness. 

If you have any questions on fungicides or your crops please contact your local LG Seeds Technical Team Agronomist.