SCIENTIFIC COMMITTEE, JUNE 9. 



clxiii 



SCIENTIFIC COMMITTEE. 



June 9, 1903. 



Dr. M. T. Masters, F.R.S., in the Chair, and seven members present. 



Larch, Diseased. — Mr. Massee, V.M.H., gave the following report 

 on branches sent by Mr. Elwes, F.R.S. : " The ample material sent 

 showed that the diseased condition was due to two distinct causes : 

 1. the yellow and bent leaves were caused by the aphis known as Chermes 

 laricis ; 2. the exudation of resin on the branches was due to the 

 presence of the fungus called Dasyscypha calycina (formerly Peziza 

 Willkommii). The relative immunity and susceptibility of trees growing 

 on varying kinds of soil, and occupying different positions in a plantation, 

 as pointed out in the letter accompanying the specimens, can only be 

 solved after an exhaustive examination of a number of plantations, 

 situated in different parts of the country, has been carried out. This 

 implies field work, and cannot possibly be solved in the laboratory." 



Diseased Plum trees. — Dr. M. C. Cooke, V.M.H., reported : " The 

 fungus will be found described in the Journ. R.H.S. vol. xxvi. p. 742, 

 fig. 313, where its ravages are depicted as a wound parasite affecting the 

 wood. The mature condition is Eutypella Prunastri, but the portions 

 sent me only exhibit the condition of conidia known as a species of 

 Cytospora. These appear on the bark of living trees. Later on, and 

 after the wood is quite dead, the mature pustules of the Eutypella are 

 developed. I have never seen the perfect fruit exhibited upon any but 

 dead wood. It is quite akin, and closely allied to the Valsa ambiens of 

 Apple-trees. I doubt whether any successful method can be adopted 

 when trees are once attacked, but preventive measures may be used by 

 spraying healthy trees with Bordeaux mixture, so as to kill external 

 germs which may be lurking to find admission. When branches are 

 seen to be attacked, it is better to prune off the branch below the 

 infection, and burn the diseased wood, at the same time taking care to 

 protect the wound caused by the amputation. The disease is liable to 

 spread from tree to tree throughout an entire orchard unless some such 

 heroic measures are adopted." See .Journ. R.H.S. xxvii. p. 691, fig. 173 ; 

 Ibid, xxviii. p. 4, figs. 2 and 3. 



Mangold diseased. — Mr. Massee showed pieces of roots cut up for 

 manure. They were badly attacked by the fungus Phoma rabitica, 

 which infests the Sugar Beets on the Continent. On inquiry he found 

 that one-half of the stored roots of the " Yellow Globe " were diseased. 

 It was the second year of the appearance of the fungus. 



Larch killed by salt spray. — Mr. Massee alluded to trees some twenty- 

 five miles inland, which were killed in the gale last March, and alluded 

 to other instances when salt was detected on the leaves of trees from 

 thirty to fifty miles distant from the sea. Dr. Masters mentioned the 

 remarkable case of a Japanese Maple on Messrs. John Waterer's grounds. 



