Identifying and Managing Diplodia Stalk and Ear Rots
Diplodia Stalk and Ear Rot in Corn
Diplodia is typically known as an ear disease in Central Illinois that produces a white fuzzy growth after silking during wet years. Diplodia is caused by the fungi, Stenocarpella maydis. Diplodia can cause seedling blight, stalk rot, leaf blight, and most famously, ear rot. The white growth is Mycelium, or the vegetative part of a fungus. The black specks are Pycnidia or the fruiting body of the fungi. Infection can occur two ways, traveling from exposed silks to the kernels or through penetrating the husk.
Primary Reasons for Infection
- Fungi overwintering in corn debris. Corn on corn or minimum tillage is generally worse.
- Moderate temperatures and wet weather at silking or shortly thereafter.
- Susceptible hybrids (genetic resistance and/or upright ears).
Secondary Reason for Infection
- Hybrid “Flowering Timing.”
- Drought conditions prior to silking.
- Bird and insect damage to ear after silking.
- Harvest affected fields first.
- Dry affected fields or take grain to market.
- Moisture should be below 15.5%. Preferably 14% or less.
Long Term Storage
- Screening grain before long term storage is advantageous.
- Cool stored grain below 50 degrees as soon as weather permits.
- Cool grain as close to 32 degrees as possible for storage through winter.