Golf courses and home lawns throughout the state have been experiencing sick turf recently. The symptoms include circular patches of bronzed or browned turf and patches or rings of straw- colored turf. The problems have been diagnosed as summer patch or take-all, two distinct fungal diseases that attack the roots and crowns of grass plants. Summer patch , once known as Fusarium blight , is caused by the fungus Magnaporthe poae.
Symptoms usually appear when typical warm summer weather begins.
This year, prolonged heat starting about 2 weeks ago has promoted disease development. In the Plant Disease Clinic, we wash out roots of plants from the margins of patches and examine them under a dissecting or compound microscope for the presence of superficial, dark-colored fungal growth called ectotrophic hyphae. In Iowa, we frequently see summer patch in home lawn situations where sod has been laid on heavy clay soil within the last few years. Many times, these sites occur in newer housing developments in which little topsoil has been allowed to remain. These sites seem to be prone to environmental stress during midsummer, and summer patch has often been linked to stressed turf.