Purdue News

August 7, 1998 Rusty grass gives homeowners orange soles, lawn blues WEST LAFAYETTE, Ind. -- If walking across your lawn turns your white tennies orange, it's not the detritus of a massive Chee.tos fest on your lawn. It's from a lawn disease called rust that is especially prevalent this summer in Indiana. According to Zac Reicher, Cooperative Extension Service turfgrass specialist at Purdue University, rust often occurs in Indiana in September. This year, however, the rust came early. The rust fungus is killed each year by Hoosier winters, but, in the southern regions of the country, rust never sleeps. "Rust infects Hoosier lawns late in the summer after it is blown in from the South on upper-level winds," Reicher said. "The unusual winter weather during the past year may have allowed rust to overwinter farther north, which in turn caused us to see infections much earlier than expected. "Plus the above-average rainfall and high humidity are creating conditions that are perfect for a rust outbreak." Rust appears on lawns as reddish-orange lesions or spots on the leaf blades and a rust-colored powder that you can rub off with your fingers. The fungus will rarely kill a turf area, but it can substantially thin a lawn, especially this year when it probably will stay active well into September. Because rust is most common on slow-growing, underfertilized lawns, the best control is an application of fertilizer, Reicher said. "This control method is fine for late August infections with the fertilizer applied in early September, when we recommend an annual fertilizer application anyway," he said. "If you have a minor rust outbreak on your lawn, consider just living with the disease and wait until September to apply fertilizer, following the manufacturer's guidelines." For homeowners with a serious rust problem who decide to treat the disease immediately, Reicher cautioned not to apply more than one-half to three-quarters of a pound of nitrogen fertilizer per 1,000 square feet of lawn. He also said that homeowners should use a fertilizer that is at least 30 percent to 50 percent slow-release nitrogen, such as sulfur or polymer-coated urea, urea formaldehyde, or natural organic fertilizers. "Apply the fertilizer on a cool day, early morning or late evening, and be sure to water it in immediately after application," Reicher said. CONTACT: Reicher, (765) 494-9737; e-mail, zreicher@dept.agry.purdue.edu; Web, https://www.agry.purdue.edu/agronomy/turf/turf.htm Compiled by Chris Sigurdson, (765) 494-8415; E-mail, sig@ecn.purdue.edu Purdue News Service: (765) 494-2096; e-mail, purduenews@purdue.edu To the Purdue News and Photos Page