Montana infected needles fell ai all seasons, while Wilson and 

 Wilson (70) reported that the needles were him aftei spores were 

 sheil. In the 1 i u 1 1 1 ol the present studies, it appears that both reports 

 are right. Needles are shed at all seasons in New York, but this is 

 a result ol weak infections and late infection ol Lammas shoots. The 

 majorit) ol infected needles are shed during the summer months 

 following ascospore discharge. 



Normal needle retention in Douglas-fir was observed b) Pease 

 (41) to average from three to nine years. Groom (21), Sargent (50), 

 ami Sudworth (57) all reported "about" eight years. Since infection 

 1)\ R. pseudotsugae eanses needle casting in one year, or two at the 

 most, there is an abrupt decline in photosynthetic capacity and 

 resulting lowered production of wood, even in young trees. 



The persistence of infected needles beyond one year has been 

 reported, but the value of such needles to the tree was questioned 

 61). Brown (7) stated that infected needles are less effective in 

 photosynthesis, since "their prodncing power is lessened in propor- 

 tion to the amonnt of necrotic surface area." 



I.os> ol water bv diseased needles has been reported to be instru- 

 mental in needle shedding (7, 37, 49). Galloway (18), who studied 

 Coleosporium rust of eastern white pine (Pin us strobus L.), reported 

 increases in evaporation of as much as one-fifth above the normal 

 rate as the fungus ruptured the needle tissue. This increase resulted 

 in "loss of turgidity and other physiological changes" and shedding 

 of needles. Brown (7) related the loss of water to the premature 

 casting of Rhabdocline-infected needles, but Van Vloten (63) found 

 that neither water loss nor degree of infection influenced needle fall. 



In New York, consecutive infections normally resulted in the 

 complete defoliation of twigs. Rohde (48), in comparing the two 

 needle cast diseases. A del opus gdumanni and Rhabdocline pseudot- 

 sugae, stated that the latter fungus invariablv left a certain number 

 of needles uninfected, even in epidemic outbreaks. In New York 

 plantations heavily diseased trees often have their lower branches 

 entirely devoid of needles except lot those of the current year. In 

 addition late frosts may kill many buds as the new needles are about 

 to emerge. This occurred sporadically in the spring of 1956, but vet \ 

 heavily in 1957. Hnbeit (23) remarked that defoliated trees in Mon- 

 tana had a moth-eaten appearance. This was tine with even mod- 

 erately infected trees in New York, especially when the new tips 

 had been frosted (Fig. 4). 



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