[ISU Extension][IA State University]

Please help ID this problem (pictures are below)

These plants are from a hayfield just east of Carroll in Carroll county.   The field was just cut and baled yesterday

Symptomology
Blueish-gray mold growing on lower portions of alfalfa stems, from base to four inches up the stem.  Some mold on leaf margins of newly emerging leaves.  Black lesions on stems as well.  Crown and roots look to be healthy.  The mold is found in scattered spots in the field, one square foot areas to elongated infected areas stretching eight to ten feet.  We did find one spot where the disease was in a perfectly round ring, about ten feed in diameter (see picture)

Field history
Alfalfa seeded with Oats in 2000
Just completed harvest of 2nd crop
Heavy leafhopper infestation

Click on photos to enlarge