Septoria leaf blotch
Area of impact: Leaf
Description: Caused by two types of fungi. Lesions caused by Septoria tritici are long and brown with irregular margins and tiny black specks. Lesions caused by Stagonospora nodorum are lens-shaped brown and surrounded by a yellow halo. Both fungi start in the lower leaves and move upward.
Pathogen involved: Septoria tritici or Stagonospora nodorum (fungi)
Timing/Conditions: Spring infections tend to do the most yield damage. S. tritici prefers cool moist weather. S. nodorum is less temperature-dependent but prefers mid- to late stages of crop development.
Contributing factors: Both fungi oversummer in previously diseased wheat stubble.
Management practices: Crop rotation, plow under wheat residue after harvest plant resistant varieties and disease-free seed, avoid excessive seeding rates, apply nitrogen carefully and limit canopy density.