If your corn crop is affected by Goss’s wilt, don’t bother spraying, says a DuPont agronomist.
“This disease can overwinter in the soil and crop debris for a few years, so if growers have had a problem before, it could be an issue again this year,” DuPont Pioneer area agronomist Wilt Billing said in a release.
It said while Goss’s wilt remained isolated to eastern Manitoba in 2012, 2013 has already seen some intense storm systems that could cause it to emerge as a problem for corn growers in southern Manitoba.
Historically, infections in Western Canada have been limited to the Red River Valley in Manitoba. Depending on weather conditions and hybrid susceptibility, the disease may cause only minor problems or it may result in devastating damage, such as yield losses approaching 50 per cent, DuPont said.
It said several conditions must be present for Goss’s wilt to produce significant damage. If the bacterium is already present in the field and a susceptible hybrid is planted, the next main contributing factor is severe weather. Wind, sandblasting and hail create wounds for the bacteria to enter. Wet weather and high humidity are also needed for escalation of disease development.
Billing said scouting is important because the disease can also look like normal environmental stresses such as sun scald and drought stress, which makes scouting for it even more vital.
Mid-season 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.
“A fungicide application will not work on bacterial diseases such as Goss’s wilt. The best strategy is prevention in the off-season with selection of a hybrid containing native resistance to the disease and incorporating crop rotation and tillage to minimize survival of the bacteria,” Billing said.