PASTURE DISEASE MANAGEMENT

              Craig Roberts, Department of Agronomy
                         (573) 882-2001
          Jeanne Mihail, Department of Plant Pathology
                         (573) 882-1471
                 University of Missouri-Columbia

MISSOURI PASTURES
     Missouri has 17 million acres of forage crops, which include
many species. Nearly all Missouri pastures are comprised of grasses
and legumes. They are annuals, perennials, short-lived perennials,
and biennials. 

PRODUCER DECISIONS
     When making management decisions, forage producers must
remember that disease is only one cause of stand loss. Other causes
include sporadic or extreme temperature changes, drought, insect
damage, and overgrazing. Each one of these causes affects
individual forage species and cultivars differently. Therefore,
producers must manage with an understanding of which factors affect
each forage. Understanding each forage' s susceptibility will help
decide which cultivar to select, determine grazing periods, and
allow for reseeding.

CULTIVAR SELECTION
     Because most Missouri forages are perennials, producers expect
stands to persist longer than 1 or 2 years. They should look for
opportunities to establish disease-resistant cultivars. This is
especially important when planting crops such as orchardgrass.
Producers should explore new cultivars such as " Justus,"  a new,
rust-tolerant cultivar recently released by the University of
Missouri. If producers cannot identify a resistant cultivar of a
given species, they should consider planting a similar species that
has resistant cultivars. This principle holds true for both annuals
and perennials. For example, if producers intend to plant annual
lespedeza but anticipate disease problems, they should not plant a
Korean type, regardless of the cultivar. They should probably plant
a Kobe (common) type instead. Kobe types are resistant to many
diseases, but Korean types are not.

NATURAL RESEEDING
     When planting a disease-susceptible forage, producers must
manage the stand, not necessarily the plant. For example, if they
plant birdsfoot trefoil, a forage noted for susceptibility to root
and crown rot, producers should manage the crop as a biennial. In
so doing, they must be willing to accept considerable loss of
individual plants, yet at the same time, maintain a viable stand by
allowing new plants to be established through natural reseeding.
When planting an annual, they should select a cultivar noted for
high seed production and view hard seed count as a positive trait
for persistence against foliar diseases. Their stands of annual
lespedeza, for example, can be destroyed by tar spot but still
persist if hard seed from the previous year have not germinated.

OTHER CONSIDERATIONS
     Producers must recognize other factors that influence forage
persistence. They should examine environmental factors, such as
soil type or condition. If soil is sandy, the potential for
nematode infestation is high. If soil is water-logged, potential
for other diseases increases as well. If soil is deficient in
nutrients, fertilizing can improve disease resistance.
     In addition to the principles and recommendations listed
above, chemical treatments can also reduce disease problems. In
forages, fungicides and nematicides are normally applied in the
establishment year, but not other years. A list of some of these
chemical treatments is given in the GRASS AND PASTURES DISEASES 
menu option.

ADDITIONAL INFORMATION
     As stated earlier, understanding the disease susceptibility of
each forage is necessary in order to manage a pasture effectively.
Additional information regarding each of the major forages is
available through local University Extension offices. For specific
information, refer to the following MU Guides: Orchardgrass (MU
Guide 6710), Reed Canarygrass, Ryegrass, and Garrison Creeping
Foxtail (MU Guide 4649), Tall Fescue (MU Guide 4646), Bluegrass (MU
Guide 4610), Bermudagrass (MU Guide 4620), Big Bluestem, Indiangrass,
and Switchgrass (MU Guide G4673), Caucasian Bluestem (MU Guide G4674),
Crownvetch (MU Guide 4510), Annual Lespedeza (MU Guide G4515), Alfalfa
(MU Guide G4550), Red Clover (MU Guide 4638), White, Ladino and
Sweet Clover (MU Guide G4639), Birdsfoot Trefoil (MU Guide 4640),
Sclerotinia crown and stem rot of alfalfa (MU Guide G4558),
Alfalfa diseases in Missouri (MU Guide G4551).