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MISCELLANEOUS PUBLICATION 1271, U.S. DEPARTMENT OF AGRICULTURE 



later season of grazing, and provide more alter- 

 natives in management strategy. 



The timely removal of shoot apices and seed- 

 heads of grasses with culmed vegetative shoots 

 promotes tillering and reduces summer dormancy. 

 Grazing practices for timothy (Phleum pratense 

 L.) have been defined in terms of shoot morpho- 

 genesis (20). Timothy has culmed vegetative 

 shoots and prominent crowns or proaxes (11). 

 Grazing is started when the leaves from the 

 crowns are well developed, but is stopped when 

 the young seedheads are 5 to 8 cm. above the 

 ground. Grazing is started again when the seed- 

 heads are exserting from the uppermost leaf 

 sheath, and when new tillers are beginning to 

 show; but this time the shoots are grazed down 

 closely. The pasture can be mowed after the sec- 

 ond grazing to stop all first-crop shoots, if uni- 

 formly close grazing is not attained. Thereafter, 

 the next crop of shoots develops basal leafiness 

 quickly, especially when properly fertilized and 

 watered; and the sequence, of graze, rest, graze 

 is repeated. Three crops of shoots and six periods 

 of grazing can be attained in a season. This mor- 

 phogenetic basis for rotation grazing is appro- 

 priate for many species. 



Growing seasons on semiarid rangelands are 

 generally short. Thus, limited regrowth oppor- 

 tunities must be defined carefully. Native and 

 introduced species may be integrated to improve 

 forage production and utilization. For example, 

 the introduced species crested wheatgrass ( Agro- 

 pyron desertorum (Fisch.) Schult.) can be 

 used to advantage with big bluegrass (Poa ampla 

 Merr.) and bluebunch wheatgrass (Agropyron 

 spicatum (Pursh) Scribn. & Smith) (23, 24). 



Big bluegrass has culmless vegetative shoots 

 and an intermediate percentage of shoots becom- 

 ing reproductive. Growth begins in March; leaf 

 heights are up about 12 cm. in early April; and 

 reproductive shoots head out in early May. The 

 main problem is weak rooting and extensive pull- 

 up. Thick stands are needed for high productiv- 

 ity, low percentage of reproductive shoots, and 

 greater resistance to pullup. The very early 

 growth, good regrowth from culmless vegetative 

 shoots, and good palatability of cured herbage 

 suggest a sprirtg-fall pattern of grazing. Pastur- 

 ing can be scheduled in April to utilize and stop 

 further development of reproductive shoots. 



Thereafter, the culmless vegetative shoots pro- 

 duce, in May and June, a good amount of leafy 

 regrowth that can be grazed in late summer and 

 faU. 



Crested wheatgrass, which is about 3 weeks be- 

 hind big bluegrass, has culmed vegetative shoots 

 and a large percentage of reproductive shoots. A 

 primary undesirable feature is the growth of stiff 

 culms that become unpalatable and interfere with 

 subsequent grazing. For good forage quality and 

 palatability, the first crop should be harvested in 

 May and June. The reproductive culms have 5 

 to 7 phytomers. The first elongated internode, 

 which generally remains less than 1 cm. in length, 

 matures, enlarges, and accumulates carbohy- 

 drates at an early time. When four leaf blades 

 are showing, the rudimentary seedhead is still 

 near the soil surface. Close clipping or grazing 

 at that time removes the leaf blades and causes 

 the culms to arise without leai replacement (7). 

 When five leaf blades are showing and the seed- 

 heads are up in the boot stage, all meristematic 

 tissues can be removed. Thereafter, regrowth is 

 composed of new tillers from axillary buds. 

 Greatest production of good quality forage can 

 be obtained by grazing to produce one crop of 

 shoots under the semiarid conditions of the sage- 

 brush-bunchgrass range. Pasturing should begin 

 when the seedheads are high in the boot and con- 

 tinue to full and uniform utilization by July. 

 Earliest satisfactory grazing can be obtained by 

 grazing to produce two crops of shoots. Pastur- 

 ing should begin when the leaves are 12 to 15 cm. 

 tall and continue (about 3 to 4 weeks) to full 

 and uniform utilization by the normal time of 

 head-in-boot development in late May. If second- 

 crop regrowth is sufficient to justify pasturing, a 

 second grazing can be scheduled after the second 

 crop of shoots has dried up. 



The herbage of bluebunch wheatgrass is largely 

 reproductive shoots, because the culmed vegeta- 

 tive shoots generally remain very small. A strik- 

 ing weakness is evident in culm growth. The low- 

 ermost elongated internode remains active for 

 several weeks, grows to a length of about 7 cm., 

 and is extremely slender and fragile until about 

 the time of seedhead exsertion. Weakness in the 

 lowermost internode makes the plant susceptible 

 to damage by grazing. The great susceptibility of 

 this species to spring grazing has been known for 



