Why does my field look patchy and have poor emergence even though there was good moisture for germination?
This could be due to seedling blight, which is also known as damping off, seed rot or root rot.
What is seedling blight? What are the symptoms?
Seedling blight is a fungal infection that causes the seed or seedling to rot and die. It can be characterized by patches in the field that fail to germinate. If the seedlings do manage to germinate, they may not emerge, or they may emerge and then become brown, pinched, and die. Other symptoms include stunted and yellow growth, or reduced root growth with brown spots on the roots and coleoptile.
What causes seedling blight?
There are many fungi present in the soil that can cause seedling death. Among these fungi are Pythium spp., Fusarium spp., and Rhizoctonia spp. Most infection is soil borne, but it can also be seed borne.
Which crops can be affected?
All crops can be affected by one or more of the fungus pathogens.
What can I do to prevent seedling blight?
Plant good quality seed to prevent severe infection; get the seed checked at a lab prior to seeding. Seed treating before planting helps protect the seed and newly emerging seedling. Plant shallow so the seedling does not rely on its seed reserve for too long; planting deep causes slow emergence, increasing disease incidence and severity which creates a weak seedling. Avoid planting cracked seed as this allows the pathogen to enter the seed and can increase the infection rate.
How does weather affect seedling blight?
Cool, moist conditions in the spring slow seed germination and emergence which increases the occurrence of seedling blight, compared with a warm, dryer spring. Pathogens vary depending on weather conditions. Pythium spp. tends to thrive in cool, wet spring conditions whereas Rhizoctonia tends to favour cool, dry spring conditions.