126 "Black Neck" or Wilt Disease of Asters 



disease. The roots of infected plants are shrivelled and decayed, but 

 infected seedlings often produce new roots so postponing the effects 

 of the attack. 



This disease is prevalent wherever asters are grown, but a complete 

 study of it does not appear to have been made. It was first described 

 by Galloway 1 in America in 1896, an undetermined species of Fusarium 

 found upon the roots being named as the causal organism ; W. G. Smith 2 , 

 in this country, at a later date attributed a disease having similar 

 symptoms to a fungus possessing oval spores, which, however, were not 

 figured nor was the species identified. E. E. Smith 3 again in America 

 described the disease, associating it with a fungus which blocks the 

 conducting tissues of the vascular bundles, but as before the fungus 

 was undetermined. More recently Osterwalder 4 has given Fusarium 

 incarnatum as the cause of the disease, but having failed to see his 

 paper or an abstract of it I have no knowledge of the evidence upon 

 which his conclusions are based. Massee 5 has described a disease of 

 sweet peas, asters, and other plants which he attributed to Thielavia 

 basicola. He found that asters were always killed outright in the 

 seedling stage but no inoculation experiments upon seedlings were 

 described. In the present investigation Thielavia basicola has never 

 been observed upon diseased seedlings or older plants. 



On the other hand, Friend 6 in 1897 ascribed it to the attacks on 

 the roots by an organism which he named the Aster Worm (Eneliytraeus 

 parvulus). W. G. Smith 7 also found nematode worms living on the 

 decaying parts of diseased plants. Occasionally I also have observed 

 these worms on diseased roots, but the infection experiments described 

 below indicate that this is not the direct cause of the wilt disease. 



Among the saprophytic fungi present on the rotting roots and the 

 lower parts of the stem of badly diseased plants there is usually found 

 a species of Fusarium, and this fact seems to have led to its identification 

 as the causal organism of the wilt disease. Up to the present, however, 

 no account of any infection experiments with this fungus on living asters 

 has been given. The results of such experiments described in this 

 paper indicate that while the Fusarium may be a secondary or accessory 

 factor, it is not the primary cause of the disease. It has already been 



1 American Gardener, vol. 17, p. 518. 



2 Gardeners' Chronicle, July 1900, p. 75. :! Hull. Mass. Agric. Coll., 1902. 

 1 Landw. Jahrb. Schwciz., Bd. 24, 1910, pp. 247-8. 



5 Kew Bulletin, 1912. 



6 Gardeners' Chronicle, 1897 (August). 7 loc. cit. 



