Have you been walking around the soccer fields, football fields, or just your own lawn lately and discovered that your shoes are covered with an orange dust? University of Illinois fans don’t mind this color, but most would like to know the cause. The orange dust is actually a mass of spores of the rust fungus that is prevalent on turf again. See issue No. 13 of this newsletter for more details on rust of turfgrass.
The rust fungus remains on the foliage. Whenever the weather favors mycelial growth and spore germination, the foliage becomes infected again. Favorable conditions for infection by this fungus include temperatures near 70°F and some leaf wetness. After infection, the fungus can thrive in temperatures from 68 to 86°F, especially on stressed turf. We see heaviest infection levels in drought-stressed lawns, areas of poor nutrition, and areas in which grass is growing slowly. Control measures for rust have been addressed in issue No. 13.