conditions alone do not provide the full answer because moist years or 

 periods, favorable for intensification and spread of the fungus, cer- 

 tainly must have occurred in the past. 



Evidently the fungus cannot perpetuate itself without the presence 

 of the alternate host. Accordingly, the epidemic may be accounted for 

 by a marked increase, perhaps an invasion, of chickweeds on areas adja- 

 cent to and within the affected fir stands. At least two of our common 

 and well-known chickweeds, Stellaria media and Cerastium vulgatum , are 

 exotics that now occur over most of North America. These two plants are 

 present on many of our mountain range lands. Changes have occurred in 

 the composition of forage plants on such lands and it is entirely pos- 

 sible that chickweeds are now more common than they were in the past. 



ECOLOGY OF CHICKWEEDS 



No special studies have ever been conducted on the ecology of 

 chickweeds. The available information on these plants is based largely 

 on observation. According to the Range Plant Handbook (11), chickweeds 

 are common and are found on a wide variety of sites, but the majority 

 of the species occur in moist or wet places. They also often concentrate 

 in shaded or partially shaded places. Stellaria jamesiana is a native 

 perennial species ranging over most of the West (11) . It is a common 

 plant in this region, occurring in the aspen and the fir-spruce belts. 

 This species has tuberous rootstocks which enable it to propagate vege- 

 tatively as well as from seed. For the most part chickweeds are small, 

 sparse in stand, and relatively unimportant as range plants (11). Graz- 

 ing animals, therefore, probably interfere little with the normal repro- 

 duction of these plants. 



CONTROL 



No attempt has been made to control the disease because it has 

 never been regarded as serious enough to warrant special attention. 

 Eradication of chickweed from the vicinity of the firs would ultimately 

 eliminate the disease, but chickweed is so abundant that this is consid- 

 ered as not feasible in either this country (_3) or Europe {$) . However, 

 the plants probably could be killed with some of the present-day herbi- 

 cides. 



Tests are now under way with fungicides applied to the witches' 

 brooms. If these materials should prove effective it probably would be 

 feasible to apply them on high value areas such as summer home sites, 

 campgrounds, and around ranger stations. Cutting the brooms from 

 branches in young trees might provide some measure of control of the 

 disease locally. A test of this kind is under way. 



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