Cause Unknown, but it is suspected that physical damage caused by thrips as the females insert eggs individually through the epidermis of the stem opens up the stem area to invasion by pathogenic bacteria. If bacteria are responsible, they likely survive in infested residues. This problem has been observed since before the mid-1990s in orchardgrass but is not considered to be yield limiting.
Symptoms The primary symptom is death of inner stem tissues, and panicle may not emerge from boot. Affected stems appear healthy green in outer tissues, but the panicle appears tan while inner stem tissues are brown, soft, and somewhat sticky. Eventually the stem completely dies and turns brown. Affected plants often appear stunted.
Control None known at this time.