Disease Guide
University-rated fungicide efficacy, pricing per acre, and spray timing for anthracnose leaf blight (Colletotrichum graminicola). Based on Crop Protection Network 2025 data.
Anthracnose leaf blight is a foliar disease of corn caused by the fungus Colletotrichum graminicola. It is unique among corn foliar diseases because the same pathogen also causes anthracnose stalk rot and top dieback — making it a dual-threat that can attack both leaves and stalks throughout the growing season.
The disease produces tan to brown, spindle-shaped or irregular lesions on corn leaves, often with dark brown or reddish-brown borders. Lesions typically start on lower leaves and move upward. In warm (75-85°F), humid conditions with frequent rainfall or extended dew periods, the disease can progress rapidly. Continuous corn and reduced-tillage fields are at highest risk because the fungus overwinters on infected corn residue.
Yield losses from the leaf blight phase alone are typically 5-20%, but the real danger is the connection to stalk rot. Plants weakened by heavy leaf blight lose the ability to maintain stalk integrity during grain fill, leading to late-season stalk lodging. In fields with anthracnose history, protecting leaf health with a fungicide at VT-R1 serves double duty — preserving both photosynthetic capacity and stalk strength.
Efficacy ratings from the Crop Protection Network 2025, based on multi-year university field trial data. Only products with tested ratings are shown — untested or not-listed products are excluded.
| Product | Mode of Action | Anthracnose Rating |
|---|
Source: Crop Protection Network 2025. Ratings reflect multi-year, multi-location field trial performance.
Efficacy ratings cross-referenced with real purchase prices. Products sorted by efficacy rating — best performers first.
| Product | Anthracnose Rating | Best $/Acre |
|---|
Prices as of early 2025 from AgChem, FBN, and Farmerceag. Actual pricing varies by geography, volume, and timing.
Apply at VT-R1. The standard fungicide timing of VT (tasseling) to R1 (silking) provides the best protection against anthracnose leaf blight. This keeps the upper canopy healthy during grain fill and helps the plant maintain stalk integrity — critical because the same pathogen can cause stalk rot later.
Scout lower leaves at V8-V10. Anthracnose leaf blight often appears on lower leaves early in the season. Look for tan, spindle-shaped lesions with dark borders. If you see significant lower-leaf infection by V10-V12, plan on a VT-R1 fungicide application.
Strobilurins work well. Products containing FRAC Group 11 (strobilurin) active ingredients are particularly effective against anthracnose. This is one disease where even budget strobilurin options like generic azoxystrobin can provide Very Good control.
Watch for top dieback. If you see the upper part of the corn plant dying and the stalk turning shiny black, that's anthracnose stalk rot and top dieback — the stalk phase of the same pathogen. By this point, foliar fungicide won't help the affected plants, but it signals that the field has heavy anthracnose pressure and future management adjustments (resistant hybrids, crop rotation) are warranted.
Efficacy ratings for all 26 products across 7 diseases, pricing from 3 suppliers, decision frameworks, and an ROI calculator.
View full guide →Search and filter 9,196 yield records from 867 university field trials by year, state, and crop.
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View guide →Based on Crop Protection Network 2025 data, the top-rated fungicides for anthracnose leaf blight include Quadris, Headline, Aproach, Quilt Xcel, Delaro 325, and Stratego YLD — all rated Very Good. Strobilurin-containing products (FRAC 11) are particularly effective against anthracnose leaf blight.
Anthracnose leaf blight produces tan to brown, spindle-shaped or irregular lesions on corn leaves, often with dark brown or reddish-brown borders. Lesions typically appear on lower leaves first. In severe cases, the fungus can also cause anthracnose stalk rot and top dieback, where the upper portion of the plant dies prematurely — a symptom unique to this disease.
The optimal spray timing for anthracnose leaf blight is VT (tasseling) to R1 (silking). Scout lower leaves starting at V8-V10 for early lesions. Because anthracnose can also cause stalk rot later in the season, protecting leaf health early helps the plant maintain stalk integrity through grain fill. Continuous corn and no-till fields are at highest risk.
Yes. Colletotrichum graminicola causes both anthracnose leaf blight and anthracnose stalk rot. The stalk rot phase can lead to top dieback — where the top of the plant dies and the upper stalk becomes shiny black. Plants weakened by leaf blight are more susceptible to stalk rot. Maintaining leaf health through fungicide application at VT-R1 can reduce the severity of the stalk rot phase.
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