Each plot consisted of lodgepole pines with 

 10 marked cankers and 10 marked branch shoots on 

 the same trees, and 10 comandra shoots in nearby 

 open areas. Length of marked shoots and occurrence 

 of spore-producing structures were recorded at least 

 once each month of the growing season. 



Analysis of these plots (fig. 15) tells us much 

 about the phenology of the hosts and parasite in the 

 Rocky Mountains. Comandra sprouts early in the 

 spring; it emerges through the soil soon after snow- 

 melt in mid-May or late May. Shoot growth is rapid 

 through June and into early July. Foraging by rabbits 



150 

 100 

 50 

 

 150 

 100 

 50 

 

 150 

 100 

 50 

 

 150 

 100 

 50 

 



150 

 100 

 50 

 



-1 1 1 1 1 r- 



TETON 



Lodg«pol« pin«^ 



^ Lodg«pol« pine^ 



BRIDGER 



-+- 



SAWTOOTH 



Comondr 



Lodg«pol« pine^ 



WASATCH 



31 15 30 15 31 15 31 15 30 15 



JUNE JULY AUG SEPT OCT 



Figure 15. -Phenology of C. comandrae and its 

 hosts in several National Forests in 1965. 

 The solid bars represent sporulation in 

 the various stages; A, aecial; U, uredinial; 

 P, pycnial; and T, tehal. The vertical 

 extent of the bar indicates frequency of 

 sporulation in relative terms; the hori- 

 zontal extent of the bar indicates dura- 

 tion on the time scale. The dashed line 

 shows seasonal growth of comandra with 

 reference to the scale of shoot length at 

 left. Growth of lodgepole pine is simi- 

 larly shown by the solid line. 



and ungulates reduces shoot height, and in autumn 

 after severe frosts, leaves dehisce and stems die. 

 Branch shoots of lodgepole pine begin growing in 

 early June and continue elongating through July. 

 Aecia of C. comandrae emerge about the same time 

 that lodgepole pine shoots begin growth and the aecia 

 remain abundant through early summer. Some aecia 

 continue dispersing spores well into autumn and, 

 rarely, new aecia form in early autumn. Pycnia exude 

 after the onset of aecia from late June through 

 August, some continuing into September. Uredinia 

 appear in July about the time comandra shoots attain 

 full height growth and the pines are dispersing pollen. 

 By early autumn, uredinia are inactive. Teha usually 

 appear a couple of weeks after the appearance of 

 uredinia and become plentiful in August. They 

 remain abundant until leaves and stems die in 

 autumn. 



Elevation 



To test the influence of elevation on rust 

 development, four additional plots were established 

 in the Uinta Mountains near the Upper Provo River. 

 All had southwest aspects and were located at eleva- 

 tional increments of approximately 1,000 feet in the 

 lodgepole pine zone of from about 7,000 feet to over 

 10,000 feet elevation. Comandra was not found 

 above about 8,500 feet in this vicinity even though 

 the rust occurred in cankers near the upper limit of 

 lodgepole pine. 



From the evidence of the plots, elevation has 

 a strong influence on phenology (fig. 16). Develop- 

 ment of rust was earhest and the season of develop- 

 ment was longest at the lowest elevation; with 

 increasing elevation, development of rust was delayed 

 and the season shortened. Since elevation was not so 

 clearly implicated as a factor in results from the other 

 plots (fig. 15), such conditions as aspect and local 

 weather also must affect phenology. 



Local Weather 



In order to find out more about annual vari- 

 ation in phenology and the influence of local 

 weather, we established plots in the Bear River Moun- 

 tains of Cache National Forest. Beaver Mountain plot 

 was located at 7,200 feet elevation on a southern 

 aspect in northern Utah, and Fish Haven plot was 

 established at 6,800 feet elevation on a southeastern 



17 



