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Hartnett, David C. (ed.) / Proceedings of the Fourteenth North American Prairie Conference : prairie biodiversity : Kansas State University, Manhattan, Kansas, July 12-16, 1994
(1995)

Tiffany, Lois H.; Knaphus, George
Fungus pathogens of prairie plants in Iowa,   pp. 49-54 PDF (2.9 MB)


Page 51


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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