Submitted to: Inoculum
Publication Type: Abstract Only
Publication Acceptance Date: 4/25/2005
Publication Date: 7/1/2005
Citation: Carris, L.M., Castlebury, L.A. 2005. Identification of species of Tilletia in U.S. wheat and grass seed exports. Inoculum. 56:12.
Technical Abstract: Tilletia controversa (dwarf bunt of wheat) is a quarantine pest with major impact on the worldwide movement of wheat and grass seed. Commonly used identification methods rely on morphological features of teliospores found in seed washes. However, teliospores of closely related species are difficult to identify based only on morphological features, and the source of spores in wheat and grass seed may be contaminating weeds. For example, in 2004 teliospores of T. bromi from Bromus tectorum (downy brome, cheatgrass), misidentified as T. controversa, were present in sufficiently high levels in some fields in the Pacific Northwest to prevent the export of that wheat to China. Similarly, shipments of Kentucky bluegrass seed (Poa pratensis) have been refused for import to China because they are contaminated with spores of T. bromi. In contrast, two putative new species of Tilletia have recently been intercepted by Chinese quarantine officials, one in seed of Puccinellia distans (alkali grass) from the U.S., and a second in Festuca rubra (fine fescue) from the U.S. and Lolium perenne (perennial ryegrass) from Australia. Species of Tilletia commonly encountered in wheat or grass seed shipments, including the new species from Puccinellia and Festuca/Lolium, are morphologically characterized and relationships among the weedy grass-infecting bunts and wheat bunt species are presented.