PERIODICAI. I^ITERATURE 



•801 



FAIRLY SOFT. 



Salix — species. 

 Amelanchier rotundifolia. 

 Parthenocissus quinquefolia. 

 Rhamnus frangula. 

 Staphylea pinnata. 



HAKD. 



Prunus arium. 

 Prunus cerasus. 

 Prunus domestica. 

 Prunus padus. 

 Sorbus aucuparis. 

 Sorbus aria. 

 Sorbus domestica. 

 Cornus sanguinea. 

 Vaccinium myrtillus. 

 Aristolochia sipho. 

 Viburnum lantana. 

 Plantago major. 



It is not certain that some of the hard-leaved species were not at- 

 tacked through unnoticed wounds. In general it may be said that our 

 knowledge of the fundamentals of choice of host plants by parasitic 

 fungus is not very extensive. 



J. ROESER. 



M. Busgen. Omnivorie und Specialization Bci Parasitischen Pilsen. Zeits. 

 fur Forst und Jagdwesen, 51 :144-153j 1919. 



Juglans regia. 



Robinia pseudoacacia. 



Begonia sp. (occasionally immune). 



Sambucus nigra. 



Symphoricarpus racemosa. 



Lonicera — species. 



Urtica dioica. 

 Ulmus montana. 

 Ranunculus repens. 

 Pelargonium zonale. 

 Oenothera biennis. 

 Glechoma hederacea. 



This leaflet describes in popular terms the 

 Chermes Galls various species of Chermes affecting conifers in 

 on Conifers Great Britain. Two hosts are necessary, as a 

 rule, in the complete life cycle of the insects, 

 such as spruce-larch, spruce-silver fir, etc. The spruce generations are 

 gall-forming but on the secondary hosts no galls are produced. Injury 

 to spruce under 4 years is rare. On older trees it is of comparatively 

 sn]all importance to the individual but considerable in the aggregate. 

 Injury to larch, pine, silver fir and Douglas fir may take place in the 

 nursery due to destruction of the foliage and weakening of the plants. 

 Remedial measures consist in fumigation of nursery stock and spray- 

 ing with paraffin-soft soap, or nicotine-soft soap emulsions, or dipping 

 in soft soap emulsion, for which formulas are given. C. J. H. 



Chermes Attacking Spruce and Other Conifers. Forestry Commission, Great 

 Britain, Leaflet 7, 7 pp., 4 figs., 1921. 



