By Carl Bradley
Goss's wilt of corn often is most severe after fields are exposed to high winds and/or hail damage, because the causal bacterium, Clavibacter michiganensis subsp. nebraskensis, readily infects corn leaves through wounds.
With the recent storm activity across the state, growers should be on the lookout for the appearance of Goss's wilt symptoms. Goss's wilt lesions on the leaves generally have wavy margins with a water-soaked appearance on the edges of the lesions. Dark spots, known as "freckles", almost always can be found within the lesions.
The affected areas of the leaves will have a shiny appearance when observed in the sunlight, and bacterial exudates may be on the leaves that resemble drops of maple syrup.
Goss's wilt incidence was at an all-time high in the 2011 season, with over 30 Illinois counties having positive detections via samples sent to the University of Illinois Plant Clinic. This high incidence observed in 2011 means that the causal bacteria is present in the state and can cause infections again in the 2013 season if the conditions are favorable.
Fields that are at the most risk to Goss's wilt are those that have been grown to continuous corn, have been planted to a susceptible hybrid, and have received wind or hail damage. Because other diseases and disorders can resemble Goss's wilt, it is important that suspicious samples be sent to the Plant Clinic for the most accurate diagnosis.
Be cautious of results received from test kits designed for the related bacterial canker of tomato pathogen, Clavibacter michiganensis subsp. michiganensis, because these kits have been shown to give false positives.
Bradley is a crop disease specialist with the University of Illinois. This article was reprinted from The Bulletin. Click here for the full version, which includes discussion on treatment options.