By Darrin Angus, Crop Sales Specialist
Wanstead Farmers Co-operative - Alvinston
There were many challenges this year with our corn crop. Our early planting conditions were wet and cold. Then it turned hot and we planted into dry soil. Some areas have been battling drought while other fields have had substantial rainfall. Not only will we see variability in our crops from field to field, we will also see a difference within the fields themselves.
How will this affect us when it comes to spraying fungicide on corn?
When fields are uneven, they are harder to stage. Aim to spray when the bulk of the healthiest plants are ready. Majority rules when it comes to applying fungicide.
There are two groups of fungicides, those that are targeted for protection from foliar leaf diseases and those that aimed at both foliar leaf disease and suppression of Gibberella Ear Rots. Timing of application matters, for foliar leaf disease the window of application is quite wide from early VT to brown silk R3. The application window for Ear Rot suppression is much narrower as the silks must receive the application of fungicide to be effective.
The range is R1 newly emerged silks to early R2, approximately a 5-day window. Spraying before the silks are out or after they turn brown will fail to protect against ear rot infection of Gibberella. Corn is very tall at this stage and the fungicide is usually applied with a high clearance sprayer or even by helicopter. Penetration of the spray into the canopy is critical for protecting the ear.
The importance of suppressing Gibberella Ear rots is to reduce the severity of the mycotoxin it produces called DON. This mycotoxin severely impacts on corn quality for livestock feed and also on byproducts of the ethanol industry mainly the marketability of distiller’s grain as the DON is concentrated in these products after processing. Discounts can also apply at the elevator or end user when DON is excessive. (remember 2018)
Some fungicides excel at reducing DON. The graph below was supplied by Bayer and shows how DON levels can be affected when you apply Proline at different stages of the corn.
(Image used by permission from Bayer).For protection against foliar leaf disease these conditions favor the risk of yield loss:
- Corn after corn
- Susceptible Hybrid
- No till- surface residue provides infecting spores
- High yield potential
- Rain. foggy mornings, heavy dew, prolonged canopy wetness in the forecast 2 weeks before and after VT- R1
We have had plenty of CHU (crop heat units) this year. We need to ensure the corn stays healthy and has a strong finish.
Contact your nearest Wanstead or AGRIS Co-operative branch to discuss all the options and make sure, if you do take action you are putting on the right product at the right time.