The first principle of crop scouting is to determine what is normal and what is not normal. Knowing what a healthy plant looks like is key to identifying seedling disease. When scouting for seedling diseases, look for yellowing, wilted, stunted, dead or missing plants.
- In corn, look for discolored or rotten mesocotyls, seminal roots and nodal roots.
- In soybeans, look for seedlings that pull easily from the soil, discolored or rotting root tissue, and lesions that form on the taproot or hypocotyl.
Before you head out to the field, there are several tools that are must-haves for early-season crop scouting:
- A tape measure to take stand counts
- A seed digger, trowel, or spade to dig up seeds or plants to evaluate planting depth, seedling diseases and below-ground feeding insects, like seed corn maggots.
Remember that certain weather and soil conditions favor specific pathogens. Cool and wet soils favor Fusarium and Pythium, warm and wet soils favor Phytophthora, and warm and moist soils favor Rhizoctonia.
It should be noted that a lab diagnosis is needed to confirm what pathogen is causing the symptoms. Knowing what disease(s) are present can help you choose hybrids and varieties that have good disease scores in the future and can guide decisions on the use of fungicide treated seed.
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