76 U.S. DEPT. OF AGRICULTURE MISC. PUB. 939 



moderate attack only. Larch cultivated outside its native range of 

 distribution often is very heavily attacked, susceptibility increasing, 

 broadly speaking, with sinking continentality of the culture spot and 

 varying, to a considerable degree, with provenance. 



These facts all considered, the following conclusion seems justified. 



Dasyscypha willkommii is a pathogen on Larix decidua. Though 

 of minor importance within the native range of the tree, it becomes 

 more important the more the culture conditions differ from those of- 

 fered by the home countries, unless climate and site are so unsuitable 

 to the tree that the cultures decline as a consequence of these adverse 

 conditions alone. 



Hosts (in Europe): Pinaceae Susceptibility 



Larix decidua Mill Great 



L. sibirica Ledeb. (including L. Great 

 suchaczewii Dyl.) 



L. leptolepis Gord None or low 



L. gmelini Pilger sens, lat Moderate to medium "\ Observation 



L. olgensis Henry Moderate to medium I material 



L. laricina Koch Great j relatively 



L. occidentalis Nutt Great J restricted 



L. decidua X L. leptolepis: Fi as a 

 rule greatly resistant, F 2 vari- 

 able. 



Intercontinental spread possible mainly through shipment of in- 

 fected trees or cuttings. 



Chances are great that, introduced into other areas of the world, the 

 disease will be important mainly to larches cultivated outside their na- 

 tive growth range, though the possibility cannot be excluded that some 

 larch species possesses a general susceptibility, just as L. leptolepis is 

 almost generally immune or very resistant. 



Literature: 



Hartig, R. Die Larchen-krankheiten, insbesondere der Larchenkreb- 

 spilz, Peziza willkommii m. Untersuchungen aus dem f orstbotani- 

 schen. Inst. Muchen : 63-87. 1880. 



Forestry Comn. Leaflet 16, London, Revised 1948. 



Hypodermella Needle Cast of Pine 



H. ROBAK 



Forest Research Institute of West-Norway, Stend, Norway 



Hypodermella sulcigena (Rostr.) Tub. A needle cast disease oc- 

 curring on two-needle pines in Europe. 



First symptoms occur in late summer and early autumn, the current 

 year's needles turning smoke grey to pale reddish violet, their basal 

 end often remaining green, sharply distinguished from the discolored 

 tissue. Only a few needles or all needles per annual shoot are attacked. 

 During autumn and winter, needle color changes to pale yellow brown, 

 interior resin exudations causing formation of dark dots or irregular 

 specks. Needles killed from the base are dropped. Withered needles 

 do not stiffen. 



