Early barley varieties generally escape serious rust attacks. Powdery mildew is a common disease of barley. The fungus forms white to light gray powdery growth on the leaves, sheaths, stems and glumes. In heavy infections, powdery mildew can cause premature death of leaves, especially lower leaves. No varieties adapted to Missouri have resistance, but in most years the disease is not serious.
Net blotch is a common fungus disease of the leaves.
It can be quite serious in seasons of high moisture. Septoria leaf blotch causes yellowish to light brown leaf spots. Black pycnidia form in the spots. Although this fungus disease is similar in symptoms to the Septoria leaf blotch of wheat, it is caused by a different Septoria species. It can be serious in moist and humid weather.