2014-15 Rapid Ag: Advancing Knowledge to Manage Goss’s Wilt of Corn

December 3, 2014

Principal Leader

Dean Malvick

Department

Plant Pathology

Funding Awarded

2014 Fiscal Year: $49,200

2015 Fiscal Year: $50,800

The Problem

Corn producers in Minnesota have historically had few significant problems with leaf diseases, but this has changed with the recent emergence of Goss’s leaf blight and wilt. This disease is now widespread in corn fields and more inoculum is available than ever before to increase the risk of disease. Management of Goss’s wilt is based on incomplete genetic resistance, although crop rotation and tillage are also important. Chemical sprays are not effective for disease management. Yield loss cannot be prevented where this disease occurs, and there is limited information available for assessing risk of this disease and to improve and tailor management practices for Minnesota for the short and long term.

Background

Corn is the number one crop in Minnesota in terms of acreage and cash value. Corn production in Minnesota now faces a new threat from the bacterial disease Goss’s leaf blight and wilt (“Goss’s wilt”), which can reduce yields over 35% on susceptible hybrids. Goss’s wilt was first confirmed in Minnesota in 2009, and has since been observed and confirmed in fields scattered across much of the corn production region in the state. 

Goss's wilt is caused by the bacterial pathogen Clavibacter michiganensis subsp. nebraskensis (CMN). This pathogen overwinters in infested corn residue, and preferentially infects plants that have been wounded by hail, sand-blasting, or heavy rain and wind, and is favored by planting corn on corn. However, we cannot predict where and when Goss’s wilt will occur or how much damage it will cause. Other challenges include the fact that corn hybrids with resistance to Goss’s wilt can reduce but not prevent yield loss; the pathogen population has variable aggressiveness and hybrids may not be equally resistant to all 2 pathogen types; and improved diagnostic methods are needed because disease diagnosis/misdiagnosis has been problematic. 

Objectives

  1. Determine distribution of the Goss’s wilt pathogen [Clavibacter michiganensis subsp. nebraskensis (CMN)] in Minnesota and the incidence and role of epiphytic populations on corn and weeds in infection, spread, and survival.
  2. Determine genotypic characteristics of CMN populations that influence pathogenicity and infection.
  3. Develop a specific and sensitive PCR assay for CMN to improve detection and diagnosis and to enable studies of resistance, infection, and survival of this pathogen.