Key to differentiating spots in the cotton fields

Key to differentiating spots in the cotton fields:
- 1A. Borders of spots often defined by leaf veins, creating angular or geometric appearance: Go to 2
- 1B. Border of spots not defined by leaf veins and approximately circular in shape: Go to 3
2. Select One
- 2A. Typically observed late in season; often a white sporulation is found on the underside of spots: Areolate Mildew.
- 2B. Spots dark in color, may appear early in the season and often have a "water soaked" appearance: Bacterial Blight/Angular Leaf Spot.
3. Select One
- 3A. Spots affect foliage throughout the plant, especially on upper leaves. Spots typically associated with plants affected by nutrient deficiencies or stress: Stemphylium, Alternaria or Cercospora Leaf Spots. Submit to disease diagnostic clinic for further diagnosis.
- 3B. Spots often with concentric rings and not associated with symptoms of nutrient deficiencies or stress: Go to 4
4. Select One
- 4A. Spots found typically on young plants and with dark, pepper grain-like sunken structures: Ascochyta Leaf Spot.
- 4B. Spots with concentric rings on older plants: Go to 5
5. Select One
- 5A. Spots with concentric rings, typically found on leaves within the canopy of foliage: Target Spot.
- 5B. Spots with concentric rings possibly surrounded by a yellow halo: Identification requires additional diagnosis and a sample should be submitted to a plant disease diagnostic lab for confirmation.