Southern rust has been detected in southeast Missouri. University of Missouri State Extension Plant Pathologist Kaitlyn Bissonnette indicated that southern rust was first confirmed last week in Pemiscot County in southeast Missouri.
It has since been confirmed in additional counties up the Mississippi River in Missouri, western Kentucky and southern Illinois.
By mid- to late-July, the arrival of this disease generally coincides with beginning (VT) to late (R4-R5) reproductive stages. This year’s late planting range has potentially expanded the length of time that corn plants are at risk of yield loss for the region.
Continue monitoring corn at all development stages, especially those from VT to R4. In favorable conditions, southern rust can infect, produce spores, and spread rapidly, so close scouting is critical. Southern rust movement can be monitored through the new corn ipmpipe website.
Rusts follow what is referred to as the Puccinia pathway where spores blow up from the south as the “green” bridge of host plants produce inoculum.
You can look over Kaitlyn Bissonnette’s presentation on southern rust from the 2018 Regional Corn Meeting (Editor’s Note: it’s a PDF file and probably not easily viewed on a phone).
University of Arkansas Plant Pathologist Travis Faske also posted an article on management of southern rust in Arkansas.
In addition, you may want to check out the presentation from Dr. Carl A. Bradley, University of Kentucky on management of southern rust and frogeye leaf spot. He spoke at our corn meeting in 2017.