3075 Lane 51 1/2

WARM SEASON GRASSES: THE IMPORTANCE OF ORIGIN OF NAMED VARIETIES AND NATIVE HARVESTS

Situation:

Grasses can be categorized as either warm- or cool-season, depending upon their germination and growth temperature requirement. Warm-season grasses germinate in the late spring when soil temperatures are warmer, and grow during the heat of the summer. Cool-season grasses, on the other hand, germinate early in cool soils and grow in the spring and the fall. In general, cool-season varieties can be moved farther from their origin (the location from which the breeder originally collected seed) than can warm-season varieties.

Critical Considerations:

Current named varieties of native plants are selected ecotypes that exhibit superior performance for defined areas; each notice of release has an "area of adaptation" map. The experience of the Soil Conservation Service indicates that a warm-season ecotype can be moved about 300 miles north or 200 miles south of its origin without having serious problems of winter hardiness, longevity, and disease. Movement east or west is affected by changes in precipitation and elevation. Generally, an increase in 1,000 feet in elevation is equivalent to a move of 175 miles north, though one can't carry that rule too far in latitude, since the photoperiod changes as one moves north and south while it remains the same despite elevation changes.

Varieties developed from northern ecotypes are early maturing, shorter, lower in total forage production, and more susceptible to leaf and stem diseases when moved southeastward from their point of origin. Varieties developed from southern ecotypes generally are later maturing, taller, and produce higher yields of forage. These differences become more visible when moved north from the original area of collection. However, varieties moved too far north may not be winter hardy and stands may be reduced or completely lost during year of establishment or under stress conditions applied by climate or management factors.

Description of Technique:

When seeding native species, use certified, blue-tagged seed of selected varieties known to be adapted to your site. Certified seed assures proper identity and genetic purity of the selected variety. An alternative is to use seed harvested from range or native haylands within your zone of adaptation, though range-collected seed may be contaminated with noxious weeds. The guidelines for native species do not apply to introduced species; however, each introduced species and/or variety has a definite, though greater, range of adaptation.

WYOMING'S ONLY NATIVE SEED COMPANY