280 Pflanzenkrankheiten. 



points in the direction that the disease is caused b}' improper nu- 

 tritive supply, and it seems probable that it is directh^ related to a 

 lack of balance between two or more soi) ingredients. The possibi- 

 lity of some relation to soil organisms is not entirely precluded, 

 but it is thought that the direct cause will ultimately be found in 

 some lack of balance in the nutritive supply, or possibly in some 

 toxic organic substances in the soil. 



There appears to be little doubt as to a difference in resisting 

 power toward rosette, but orchard records and observations tend 

 to show that this difference is usually manifested through the stock 

 rather than through the variety worked upon it. Good care and 

 fertilization are to be recommended, but the effects of lime should 

 be tested upon a few trees before using it on a commercial scale. 

 Pruning is of no avail as a remedial measure. Trees showing 

 only traces of rosette may be left in the orchard , but all advanced 

 cases should be cut out and replanted. On account of resistance 

 versus susceptibility of stock, the discarding of all rosetted nursery 

 trees is to be strongly advised. M. J. Sirks (Haarlem;. 



Rankin, W, H., Field studies on the Endothtac sinke r of 

 chestnut in New-York State. (Phytopathology. IV. p. 232 — 

 260. 1914.) 



Introducting this paper the writer gives a review of the distri- 

 bution of Ejtdothtaccinker in New-York State and of the condi- 

 tions in relation to disease-spreading during the j^^ears 1911 and 

 1913. The pathogenicity of Endothia parasitica (Murr.) Anders, on 

 Castanea dentata being beyond doubt, the author has made many 

 inoculation-experiments upon other plantspecies, as Qiiercus prinus, 

 Q. rubra, Q. alba and Q, coccinea, but none of them gave much 

 result; some inoculations only showed any advance into living 

 tissues. Inoculations on Castanea have also been made to investigate 

 the conditions of natural infection. The negative results with lenticel- 

 inoculations seem to prove that infection cannot be attributed in 

 any great percentage of cases to lenticel infection; neither the na- 

 tural cracks in the bark, although apparently exposing unprotected 

 tissues, are a common infection court for the fungus; the tree is 

 not naturally predisposed because of these seemingl}' morphological 

 defects in the bark. Artificial inoculation of injured parts of host- 

 plants showed in connection with the foregoing results, that the 

 fungus is strictly a wound parasite. Wounded tissues and a brief 

 saprophytic growth, sufificient to produce m5'celialfans are neces- 

 sary before living tissues can be invaded and infection accomplished. 

 The American chestnut is without regard to injurious effects of 

 environmental conditions perfecth^ susceptibk in the healthiest 

 condition. 



The following part of this paper contains measurements about 

 the rate of growth of cankers; in considering the results of these 

 records, it is apparent, that the rate of growth is less than one 

 would be led to believe from the previous litterature concerning 

 the rapidity with which limbs are girdled. A total growth of about 

 12 cM for the season can be cxpected. It would thus require a 

 period of about eight years for a Single canker to girdle the trunk 

 of a tree a feet in diameter. The concluding chapters give many 

 details and data about pycnidia, pycnospores, stromata, perithecia 



