Fontanelle
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Fungicide Application in Corn
July 13, 2009
Depending on disease pressure and hybrid resistance, applying a fungicide could result in a positive yield response. Here’s some tips to help determine if applications are needed on your fields:
Prioritize Fields Hybrids susceptible or moderately susceptible should be monitored for disease prior to tasseling. Because many foliar diseases survive on corn residue and begin producing spores when conditions are favorable, scouting fields in a continuous corn rotation is important. It is also practical to scout fields with a history of foliar disease.
Scouting Fungicides can work better at preventing rather than curing disease, as lesions may take up to two weeks to become visible after infection so scouting when the weather conditions favor disease development is important. A treatment guideline is to spray when disease symptoms have developed on the third leaf below the ear leaf and above on 50% of the plants at tasseling.
Fungicides Active ingredients from the strobilurin and triazole chemical groups can be helpful when treating fungal diseases. Strobilurins help offer activity on a broad range of foliar corn diseases. These products are intended to be used as a preventative treatment with approximately 21 days of residual activity. For fields with early foliar-disease infection, triazoles may be the better treatment. Although this class of chemistry has a shorter residual compared to strobilurins, some triazoles can help slow the spread of disease by inhibiting the production of spores.
Depending on the active ingredient, fungicide movement within plants can vary. It is still important to set up sprayers so plants get adequate spray coverage. Resistance to fungicides may be managed by rotating active ingredients each year, as well as using full-labeled fungicide rates.