- Excess water and waterlogged soils with temparily shut down small grain roots and can cause yellowing and stunting. Denitrification in these wet areas may lead to nitrogen deficiency and yellowing.
- pH problems can cause yellowing. Low pH (less than 5.3) will cause poor root growth and potential problems with Magnesium deficiency. High pH (above 6.4) will often lead to a Manganese deficiency in many DE soils.
- Compaction from equipment traffic over wet soils will lead to poor root growth and yellowing and stunting because soil is too dense for roots to penetrate. Secondary effects of compaction will be soils remaining wet longer and increased dentrification again potentially causing yellowing.
- Several diseases can lead to yellowing or browing of small grain seedling including Fusarium seedling blight, Pythium, and other seedling blights.
- Barley yellow dwarf virus can cause yellowing in spot in fields. These are usually circular in appearance.
- Nitrogen deficiency will cause yellowing in small grain seedlings. This is often most noticeable in areas where significant plant residue from the previous crop was incorporated, creating a temporary nitrogen deficiency.
- Herbicide carryover is another possible cause of yellowing in small grains. This is most common on dry years but still can happen in wetter years, especially after later planted vegetables where herbicides have not yet broken down.
Gordon Johnson, Extension Agriculture Agent, UD, Kent County