Hartnett, David C. (ed.) / Proceedings of the Fourteenth North American Prairie Conference : prairie biodiversity : Kansas State University, Manhattan, Kansas, July 12-16, 1994
Tiffany, Lois H.; Knaphus, George
Fungus pathogens of prairie plants in Iowa, pp. 49-54 PDF (2.9 MB)
FUNGUS PA THOGENS OF PRAIRIE PLANTS IN IOVA 51 Table 1. Fungal parasites of the most common tallgrass prairie grasses (Poaceae) of selected Iowa prairies. Prairies Host & Fungus 1 2 3 4 5 6 7 8 9 10 11 Andropogon gerardii (big bluestem) Rusts Puccinia andropogonis Uromyces andropogonis Smuts Sphacelotheca occidentalis Ergot Claviceps purpurea Tar spot Phyllachora luteo-maculata Leaf Spots Ascochyta agropyrina Ascochyta brachypodii Ascochyta sorghi Colletotrichunm caudatum Colletotrichum graminicola Septoria andropogonis Stagonospora simplicior Sphaerellopsis filum (On Puccinia andropogonis pustules) Schizachyrium scoparium (little bluestem) x x x x x xxx x x x x x x x x xx x x x xxx x xx xXx x x X x x x x x x x Rust Puccinia andropogonis x Tar spot Phyllachora luteo-nmaculata x x Leaf spots Colletotrichum caudatum Colletotrichunm gramninicola Stagonospora simplicior x Sphaerellopsis filum (On Puccinia andropogonis pustules) Sorghastrum nutans (Indian grass) Leaf spots Colletotrichum caudatum x Pseudoseptoria donacis Stagonospora simplicior x x Panicum virgatum L. (switchgrass) Rusts Puccinia emaculata x Uromyces graminicola Leaf spots Colletotrichunm gramninicola x Elsinoe panici x x x x x x x x xX X X x X a a xx x x x x x x x x x x x x x x xx x x x x x x x x x x x x x x x x x x x xx x x x x x x x x x a = host plant not collected it is also present on planted prairies elsewhere in the state. Another smut of big bluestem, Sorosporium provinciale, is present on native prairies only in southern Iowa and destroys the entire inflorescences of diseased host plants. Leaf spots, usually caused by species of imperfect fungi, occur on all of the prairie grasses. Some fungus species can parasitize several grass hosts, such as Stagnospora simplicior on leaves of Indian grass, big bluestem, and little bluestem (Table 1). Conversely, Elsinoe panici is a destructive leaf pathogen only on switchgrass. It does not parasitize other prairie species of Panicum, but can be lethal for its switchgrass host. Table 2. Fungal parasites of common legume (Fabaceae) hosts of selected Iowa prairies. Prairies Host & Fungus 1 2 3 4 5 6 7 8 9 10 11 Amorpha canescens (lead plant) a a Rust Uropyxis amorphae x x x x x x Desmodium canadense (tick-trefoil) Rust Uromyces hedysari-paniculati x x x x x x x Powdery mildew Microsphaera diffusa x x x x x Black mildew Parodiella hedysari x x x Leaf spots Cercospora desmodiicola x x x x x Gloeosporidiella desnmodii x Phyllosticta desmodii x x Ramularia desmodii x x x x Sphaerellopsis filum x (on Uromyces hedysari- paniculati pustules) Lathyrus venosus (bushy vetchling) a a a a a Rust Uronzycesfabae x x x x x x Downy mildew Peronospora trifoliorum x Leaf spot Cercospora lathyrina x Lespedeza capitata (bush clover) a a a a a Rust Uromyces lespedezae- procumbentis x x x x Tar spot Phyllachora lespedezae x X Pediomelum argophyllum (scurf pea)a a a a a a Rust Uromyces psoralea var. argopyllae x x x x Leaf spot Colletotrichum psoraleae x x x x a = host plant not collected Even though the black sclerotia of ergot are common in the florets of open-pollinated grasses such as western wheat grass, rye and brome, this disease is seldom present on the tallgrass prairie grasses. It has been collected once during this project, on big bluestem at Sheeder prairie. Although the smut fungi have been significant destructive parasites on agronomic grasses, the only smut fungus recorded on the native prairie grasses in this report is kernel smut of big bluestem, Sphacelotheca occidentalis. It occurs only in the native prairies of the northwestern portion of the state, although Rusts, species of Uromyces and Uropyxis, are the commonest parasitic fungi on the legume hosts (Table 2). Lathyrus venosus often is damaged severely by the extensive development of rust by mid-summer. However, two leaf-surface inhabiting fungi are the most destructive on tick-trefoil. Powdery mildew, character- ized by a grayish-white covering of fungus mycelium on the leaf surfaces, and black mildew, with a jet black, external, leaf covering, may severely inhibit the development of young leaves and stems. The resulting dwarfed plants struggle to survive.
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