Sweet Corn NCLB - Solution Guide
Northern Corn Leaf Blight (NCLB) is a disease caused by the fungus Exserohilum turcicum that causes tan to brown, linear leaf lesions or spotting on corn varieties.
When prolific infections occur, especially during early corn development, it causes substantial yield losses to hybrid sweet corn due to reduced plant vigor, and it can lead to issues from other disorders or lead to secondary disease infections.
Like any fungal disease, scouting and monitoring for symptoms is critical to control. Weather conditions play a role in fungal infections like NCLB. With this disease, wet, humid conditions along with moderately warm temps. are most conducive. Hot dry weather helps suppress this disease.
Fungal spores will overwinter on residual debris on field surfaces. When warmer spring weather arrives, rain or heavy dew leads to spore germination which is then easily spread by wind or water splashing to new host corn plants.
Of course, planting resistant varieties is beneficial to disease management. Some resistant varieties include: 'Bodacious RM', 'Illini Xtra-Sweet', 'Luscious TSW', 'Nectar', 'Peaches & Cream', 'QuickStart', 'Silver Queen', 'Sugar Pearl TSW', 'Temptress', 'Trinity'.
NOTE: Resistant varieties can also suffer from minor leaf lesions, but plant vigor is less affected. However, to maintain potential yields, all other growth factors should still be optimal such as proper plant densities, good soil composition, nutrition, and consistent moisture to get good yields.
- Corn crops grown in No-till systems are at higher risk, due to the slow decomposition of corn stalk residue that harbors the disease for reinfection.
- Tilling and other processes to promote speedy decomposition are recommended.
- Crop rotation is highly beneficial, 1 year out of corn is the minimum, and up to 2 years for susceptible hybrids, especially post-NCLB infection.
- Fungicide products like chlorothalonil can be applied, but their effectiveness will be determined by factors such as:
- The level of disease pressure
- Weather conditions
- Variety susceptibility
- Timing of the infection
- It is good to remember topical fungicides are preventative, not curative. If an infection has progressed too far, late spraying will have virtually no effect.
- Scouting should be done just before tasseling (V14) to determine the level of disease prevalence.
- If a high number of leaf lesions are discovered, it may be beneficial to apply a fungicide then.
- Most impactful timeline for fungicide application is reported to be between V14 and R1 growth stages. (Very specific)
Any growers with large fields should reach out to their local agricultural extension agent or agronomy specialist.
