. Cronartium comandrae in the Rocky Mountain States. Cronartium comandrae Rocky Mountains Region; Fungi Rocky Mountains Region. 24 hours (table 3). On the basis of both percent germination and length of germ tubes at 24 hours, germination seemed best between 13° and 23° C. and poor at 3° C. and at 28° C. or higher (fig. 6). Like aeciospores, urediniospores germinated equally well in low light (such as might occur on cloudy days) and in darkness, but did not germinate in bright sunlight. Urediniospores were also deposited on comandra shoots in the Cache National Forest plot mentioned earlier. I
. Cronartium comandrae in the Rocky Mountain States. Cronartium comandrae Rocky Mountains Region; Fungi Rocky Mountains Region. 24 hours (table 3). On the basis of both percent germination and length of germ tubes at 24 hours, germination seemed best between 13° and 23° C. and poor at 3° C. and at 28° C. or higher (fig. 6). Like aeciospores, urediniospores germinated equally well in low light (such as might occur on cloudy days) and in darkness, but did not germinate in bright sunlight. Urediniospores were also deposited on comandra shoots in the Cache National Forest plot mentioned earlier. In two trials in which 10 days of conditions unfavorable for infection followed deposi- tion, no shoots became infected. However, uredinia developed on shoots in two trials in which only 6 days of unfavorable conditions followed spore deposi- tion. Thus, even during short dry spells in a warm summer, dissemination of urediniospores can lead to infection of comandra. TELIOSPORES TeHa contain up to several hundred telio- spores bound firmly together as hairlike projections on comandra leaves (fig. 7) and stems. As soon as conditions are favorable, each teliospore may germi- nate in place and form a basidium and (usually) four basidiospores that are disseminated by air (Hedgcock and Long 1915). This process, referred to here as basidiospore casting, may lead to the dispersal of many hundred airborne basidiospores from each telium. Thus teHa and tehospores are not themselves disseminated, but produce the wind-disseminated spores that infect pines. Effects of Humidity on Germination To determine whether saturated air is neces- sary for germination of tehospores, telia were tested in petri-plate chambers in which humidity was con- trolled by saturated salt solutions or distilled water (table 4). Excised teha from comandra leaves were stuck by their basal ends to petrolatum on the inside of petri-plate covers, and glass shdes were placed beneath the teUa to catch dispersed basidios
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