RHIZINA INFLATA. 437 



healthy trees by contact between their roots and those of 

 diseased ones. 



3. Rhizina inflata, Quelet. 

 a. Description and Mode of Attack. 



This root fungus, also named 11. widulata, Fr., kills Scots 

 pines of various ages. As the malady spreads in a circle, 

 centrifugally from the point of infection, it is termed in 

 France " Maladie du roncl." It may be recognised by the 

 dying and falling of the needles of affected trees, from the 

 month of June. On digging up affected plants, the ground 

 around their roots is found bound together by numerous 

 hyphae, but there is no flow of resin, as in the case of the 

 honey fungus. From the bark of the pine-roots protrude 

 numerous white mycelial hyphae, like Rhizoctonia* which grow 

 to three or three and a half feet from the affected plants in a 

 richly branched, threadlike mycelium. Their whiteness is 

 due to drops of etherial oil, exuding from the fine hairs at the 

 ends of the hyphae. These hyphae spread in the soil, infect 

 neighbouring plants, and penetrate their wood. 



Massee states that the fungus is saprophytic on stumps and 

 on peat. It was so destructive to Scots pine, on a loamy soil, in 

 the Forest of Belleme (Orne), in France, that its cultivation 

 had to be abandoned. 



The sporocarps resemble morels, are from 1 to 5 cm. in 

 diameter, and of a dark chestnut or chocolate colour. They 

 occur in the ground, connected with the mycelium. 



I). Subjects of Attack. 



The fungus attacks plants of all ages, from four years old. 

 In Belleme, 50 years old trees were attacked. Besides Scots 

 pine, Weymouth pine, silver-fir, larch, Douglas fir and Sitka 

 spruce, also sweet chestnut have been attacked. It is sapro- 

 phytic on old felling-areas. 



c. Protective Rules. 



Mix broadleaved trees with conifers. Choose conifers 

 suitable for the locality. Isolate affected trees by trenches. 



* Rltizoctouia crocorum, D.C., forms a subterranean web of filaments, termed 

 " copper web," and attacking the crocus. 



