RESULTS 



Unthinned areas. --The three areas examined were overstocked (table 1). More than 

 90 percent of the conifer regeneration was western hemlock. The remaining conifer 

 regeneration was Sitka spruce. Considerable amounts of broad- leaf shrubs also occupied 

 the sites. 



All the western hemlock regeneration was infected by S. strobilinus (fig. 2) . 

 Infection was most severe on regeneration in the suppressed and intermediate crown 

 classes. Some of this regeneration showed severe top-killing (table 1) and a bushy, 

 broomlike growth form with no definitive terminal leader (fig. 3). It is likely that 

 earlier in the life of the stand, many of these individuals were dominants and codomi- 

 nants; the disease cost them their dominant position. All mortality attributed to the 

 disease (table 1) was in the suppressed and intermediate crown classes. 



Recent (1975 and 1976) leader kill in potential crop trees (fig. 4) was common. 

 The accumulative leader kill over a 6-year period was high (table 2). No mortality 

 or severe top-kill (fig. 3) was recorded for potential crop trees. Disease was more 

 severe in the lower crowns and least in the upper crowns in all trees examined. 



Analysis of variance showed a significant difference (P=0.05) in disease index 

 between areas and plots. We believe these differences are related to local environ- 

 mental factors not measured during the study (Wall and Magasi 1976). 



No infection of Sitka spruce was recorded on the plots examined. However, while 

 moving from plot to plot, an occasional infected Sitka spruce (fig. 5) was observed. 



Table 1 . -Stocking 3 infection, and mortality data/hectare for western hemlock and 



Sitka spruce regeneration, Thomas Bay, Alaska 



Area 



: Total 

 : trees 1 



Crop 

 trees 1 



: Infected 

 : trees 2 



: Dead 

 : trees 3 



: Top-killed 

 : trees 





No. 







Percent - - - - 





1 



59,500 



23. 1 



93.7 



10.5 



13.4 



2 



86,250 



18.8 



91. 9 



12.2 



34.8 



3 4 



55,000 



32. 7 



90. 9 



21.4 



20.5 



4 5 



1,663 



100. 



100. 







Includes Sitka spruce. 



Represents 100 percent of western hemlock. 

 All were in the intermediate and suppressed crown classes. 

 Fertilized May 1969; 464 kg Agricultural Grade urea/hectare. 

 Area thinned in 1975 to 2.4 x 2.4 m spacing. 



4 



