Have you seen Goss’s wilt in your corn fields? Chances are you haven’t, unless you farm in Manitoba’s Red River Valley. Even then, the bacteria is not widespread, and a few environmental conditions have to converge in order to create conditions for the disease to thrive.
That said, the bacteria does lurk in Western Canada, and severe weather events that cause wind or hail damage, such as have happened over a large swath of the Prairies this year, creates an opportunity for bacterial infection should a corn variety be susceptible. Wet weather or high humidity following infection is also required. Damage by Goss’s wilt may be mild or devastating, causing up to 50% yield loss.
DuPont Pioneer recently sent out a press release to draw attention to the risk of Goss’s wilt in Western Canada, and to stress the importance of big-picture management of the disease, as in-crop control options are limited.
Identifying the disease is the first step in managing it going forward — this disease can also look like sun scald or drought stress, so it’s imperative to determine the exact cause of what’s stressing your corn plants. Early season infections can result in discolored vascular tissue within the stalk. Those cases show a buildup of bacteria in the vascular bundles that inhibits the plant’s ability to transfer water. Stunted growth and wilting as if drought stressed is another symptom to watch for, according to DuPont Pioneer agronomists. Midseason signs and symptoms include distinct dark green to black “freckles” within or just outside of leaf lesions. Shiny or glistening patches of dried bacterial ooze on the lesions, similar to a thin layer of varnish, can also be observed. Other signs of infection are water-soaked streaks accompanied by tan-to-gray lesions that run lengthwise on the leaves.
Because Goss’s wilt is a bacterial infection, fungicide applications are useless. Choosing a tolerant or resistant hybrid variety and adhering to a proper crop rotation are two cultural controls at farmer’s disposal. Any management that reduces corn residue quickly or more completely may also help in decreasing the survivability of the bacteria in the soil. Good weed control is very important because weeds such as green foxtail or barnyard grass are hosts for this bacterium, according to DuPont Pioneer. Harvesting and tilling infected fields last and then cleaning your equipment to help avoid spreading the pathogen to uninfected fields is also recommended.