Goss’s wilt was reported in a corn field at low incidence in Brown county. Goss’s wilt affects corn in two phases: the wilting phase and the leaf blight phase. The disease phase being observed at this time is the wilting phase (Figure 1). The wilting phase occurs when the bacteria infects young corn plants causing entire corn plant to wilt. The leaf blight phase develops when corn leaves are infected later in the growing stage, leading to large grayish-tan water-soaked lesions on the leaves. The leaf blight phase is the most common.
Figure 1. Corn plant with Goss’s wilt symptoms. Plants infected early in the season may have all leaves wilting.
Disease Development: Causal agent & risk factors
Goss’s wilt is caused by a bacterial pathogen, Clavibacter michiganensis subspecies nebraskensis (Cmn). The Goss’s wilt bacteria survive on infested corn residues (roots, stems, leaves) and also on several other hosts including grain sorghum, green foxtail, barnyard grass, shattercane, large crabgrass, and others. The pathogen can also survive on seed (very low levels, <0.5%) and therefore seed can serve as a source of inoculum, however, corn residues by far are the main source of the inoculum. Cmn is spread through rain splash but can also be carried by high winds for a considerable distance. The Cmn bacteria enters any part of the corn plant through wounds and natural openings. Infection is favored by rainy weather especially where high winds, hail and sand blasting occur. Hot and dry weather conditions slow infection and progress of Goss’s wilt.
- Plant corn hybrids with resistance to Goss’s wilt.
- Practice crop rotation. Rotation should be between broadleaf crops and small grains other than sorghum since sorghum is a host for Goss’s wilt
- For fields with a history of Goss’s wilt, tillage practices that bury the corn may speed up decomposition therefore reducing inoculum level.