234 Journal of Agriculture, Victoria. [10 April, 1919. 



Later Investigations in the United States of America. 



Hereunder are a few extracts from Pliytopatliology, vol. 6, No. 2, 

 p. 162, 1916, " Investigation of a Troublesome Disease in Winter 

 Tomatoes," by J. C. Howitt and E. E. Stone, giving results of examina- 

 tions into the cause of tbe same mysterious disease : — 



" In 1914, tomato plants were forwarded which showed a marked 

 diseased condition of the leaves, stems, and fruit. Ten per cent, of the 

 plants in the house were attacked. The disease appeared in the same 

 house the following year. In August, 1915, the disease was observed 

 in field tomatoes in two localities." 



" Specimens showing symptoms of the disease were forwarded to 

 Professor A. D. Selby for examination. These Avere examined by Mr. 

 A. S. Orcut, who reported as follows : — ' Upon examining the tomato 

 material, and conferring with Professor Selby, it is our opinion that this 

 is the same trouble which was reported from this section in 1896.' " 



" The same disease apparently also occurs in the vicinity of Phila- 

 delphia. In January, 1915, diseased plants were forwarded to Messrs. 

 Howitt and Stone by Professor C. K. Orton, Plant Pathologist, Pennsyl- 

 vania State College. These, when carefully examined, were found to 

 have spots and lesions on the stems, leaves and fruits characteristic of 

 the disease as it occurs in Ontario." 



Symptoms of the Disease. 



" The disease affects leaves, stems, and fruits. Aifected leaves show 

 distinct brown and blackened areas scattered between the layer veins. 

 These are angular, or somewhat diamond-shaped, and are usually so 

 numerous and close together that a distinct pattern is seen when aifected 

 leaves are held up to the light. An examination with a hand lens reveals 

 the fact that discoloration is not confined to the mesophyll of the leaf, 

 but extends to the secondary veins of the vascular bundles, is clearly 

 evident. Aifected leaves do not develop normally. They at first appear 

 somewhat stunted, and, as the disease progresses, droop, and finally 

 wither and die. In most cases observed the disease appeared to start on 

 the upper younger leaves, and gradually work downward to the older 

 leaves. On the stems of affected plants brown lesions are usually seen. 

 These vary in size from 1 to 3 cm. long, and almost half as wide." 



Attempts to Discover tub Causal Organisms. 



'' When the diseased plants were received, a superficial examination 

 disclosed the blackening and browning of the vascular bundles of the 

 leaves. This symptom suggested that the trouble might be brown rot 

 of t-omato caused by Bacillus solanacearum, E.F.S. Microscopic 

 examinations were made, but no fungus or bacteria were found associated 

 with the lesions on leaves, stems, or fruit. 



" Dilution plate cultures were made, but nothing Avas found to which 

 the disease could be attributed. Fearing that in some way our technique 

 might be at fault, specimens of diseased plants were submitted for 

 examination to Dr. E. F. Smith, Bureau of Plant Industry, Washington, 

 D.C. ; Professor A. D. Selby, Agricultural Experiment Station, Wooster, 

 Ohio; Dr. E. A. Bessey, Michigan Agricultural College; and Professor 

 D, Jones, of the Bact<^riological Department of Ontario Agricultural 

 College. 



