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gal diseases are known to auack the adelgid, greenhouse and field studies in Quebec 

 have not identified a successhil control. The potential for control organisms fi-om 

 other locations is unknown (Schooley et at 1984). 



Scleroderris Canker 



Scleroderris canker is caused by the fungus Ascocalyx abietina (= Gremmmidla aUetina, 

 and infests various coniferous species in North America, Europe and Asia (Stilling et 

 al. 1986). The fungus usually causes tree mortality by producing cankers that girdle 

 a large number of branches. Two strains of the fungus are knovm in North America. 

 One, called the "North American" strain, has caused extensive damage in the Lake 

 States since at least 1950 (cf. Skilling et aL 1986). This strain is thought to be native 

 to the Rocky Mounuins, where it causes minimal damage to coniferous species, e.g., 

 lodgepole pine [Pinus amtorta) (Dorworth 1984). It attacks nursery stock, and young 

 plantations of red pine (ftnui rshruua). jack pine {P. barthsiana), eastern white pine 

 and the exotic Scots or Scotch pine {P. sylvestris). The fungus was spread by planting 

 infested nursery stock, and affected approximately two-thirds of National Forest planta- 

 tions in Michigan and Wisconsin by 1965. Approximately 40 percent of the seedlings 

 planted were killed. Fungicide treatment of nursery stock and silvicultural proce- 

 dures have now reduced the disease to manageable levels (Skilling et al. 1986.) 



In 1975, GremmenieUa abietina vas observed in New York, killing red and Scots pines of 

 all ages (Seiliff et al. 1977). Isolates were serologically identical to fungal isolates 

 found in Europe (Dorworth et aL 1977); hence the strain was called the "European 

 strain." Studies have shown that this strain has a wider range of hosts than the North 

 American strain and could infest fir (Abiei) and spruce (IHcea) species as well as pine. 

 The European strain presently occurs in northeastern North America and appears to 

 be spreading (LaFlamme and LaChance 1987, Moody 1992). Intermediate strains, 

 with the ability to attack trees of all ages, have been identified (Skilling el aL 1986.) 



The European strain can be controlled in nurseries by spraying fiuigicides and young 

 plantings by silvicultural practices. This strain, however, has the ability to attack 

 mature trees, so silvicultural control is less effective than with North American strain 

 infesuiions (Skilling el al. 1986). 



Larch Casebearer 



Eastern larch or tamarack {Larix lariana), and western larch (Larix ocddentalis) are in- 

 fested with larch casebearer ( Coleophora lancella). The moth was introduced into Massa- 

 chusetts in 1886. probably on imjjorted nursery stock from Europe (Tunnock and Ryan 

 1983. Ot\-os and Quednau 1984). Initially infesting tamarack, the casebearer spread 

 throughout the northeastern U.S. and southeastern Canada, reaching the Great Lakes 

 region in the 1950s. By 1970, it was present in southeastern Manitoba (Otvos and Qued- 

 nau 1984) . In the West, the insect was discovered infesting western larch in Idaho in 1957 

 and was considered lo be the spedes' most serious pest (Denton 1979). An outbreak oc- 

 curred in British Columbia in 1966 (Otvos and Quednau 1984), and by 1982, all the 

 U.S. range and most of the southern Canadian range of the western larch was infested 

 (Tunnock and Ryan 1983). The moth larvae feed on the internal needle tissue caus- 

 ing defoliation. Five years of defoliation can kill a tree or reduce potential growth by 

 as much as 97 percent (Tunnock el aL 1969). Younger trees growing in the open or 

 along the edges of openings suffer the highest mortality (Ttmnock and Ryan 1983). 



Control strategies relying on a combination of natural factors and introduced para- 

 sites have been successful in eastern and central Canada and the northwestern U.S. 

 (Ot\os and Quednau 1984. Graham 1949. Ryan et aL 1987). The control organisms 



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