688 EXPERIMENT STATION RECORD. 



ami iiciiiatnili's in tlic snil. Tlic author ))riefly describes a number of the more com- 

 mon <liscascs to which these })lants are subject, and p;ives an account of experiments 

 con(hicl(Ml with the object of ascertaining whether substances taken up by the roots 

 of the jihints would not render them immune to the attaciks of fungus parasites. 

 Among tlie various substances tested copper sulj^hate alone proved ada])ted to the 

 conditions of the experiment. 



Cucumber and tomato seed were sown, and the plants grown in the house having 

 a jnean temperature of 75° F. Three hundred seedlings of each kind were su1)jected 

 to the experiment, 50 of each being used as check plants. When the seedlings were 

 about 2 weeks old the cucumbers were grouped around a number of large cucumber 

 plants badly attacked with disease, and tomato seedlings in a similar way about 

 diseased tomato plants. At this period the treatment consisted of watering the plants 

 every tluT-d day with a solution containing 1 part of copper sulphate in 7,000 parts of 

 water. Tlie rlieck plants, which were not watered with the copper solution, were 

 indiscriminately mixed with the treated plants. 



After a month's treatment all the tomato plants were perfectly free from disease, 

 while one or both cotyledons of 34 of the cucumber plants showed symptoms of 

 disease. At the same time a considerable number of the untreated plants of both 

 kinds were affected. At this stage both treated and check plants were sprayed with 

 water containing spores, causing their resjiective diseases and under this treatment 

 all the check plants became badly diseased within 2 weeks. After 6 weeks' treat- 

 ment with solution of copper sulphate of the strength above indicated the solution 

 W'as increased to 1 part of copper sulphate and 6,000 parts of water and the soil about 

 the plants soaked every fourth day until the end of the experiment, which lasted for 

 11 weeks. At this time both cucumber and tomato plants were bearing good crops 

 of well-matured fruit. Not a single tomato plant treated with copi)er-sulphate solu- 

 tion showed a trace of disease and in the case of the cucumber 2)lants the disease 

 never progressed beyond the cotyledons, as noted above. An examination was 

 made of the fruits of both tomato and cucumber and only slight traces of copper 

 sulphate were present. 



The author calls particular attention to the fact that so far as his experiments have 

 been conducted the above method of treatment secures immmiity against fungus para- 

 sites when applied to cucumbers and tomatoes only. Upon other plants markedly 

 different effects were observed. Luffa ngyptiaca, a plant closely allied to the cucum- 

 ber, was killed by 2 waterings of a solution of 1 part copper sulphate and 6,000 parts 

 of water. On the other hand, barley remained perfectly healthy when treated with 

 a solution of 1 part in 500, and in addition became badly affected by the grass mil- 

 dew, Erysiplie graminis. As a proof that the solution of copper sulphate is absorbed 

 by the plants, the author quotes experiments with garden nasturtium, where the 

 effect of too strong a solution was shown by the bleaching of the tissues surrounding 

 the water stomata. Grasses similarly treated showed a like bleaching of the tips of 

 the leaves. 



Danger arising from the presence of fungi or nematodes in the soil may be guarded 

 against ])y sterilizing the soil with gas lime. 



Tomato leaf spot, D. McAlpine (Jour. Dept. Agr. Victoria, 3 {1903), No. 1, pp. 

 70, 71, pi. 1). — A description is given of the tomato leaf spot due to attacks of Septoria 

 lycopersici. This disease has become quite prevalent in parts of Australia, occasioning 

 considerable loss. Its effect as produced upon the host plant is described, and based 

 on suggestions given in Alabama Bulletin No. 108 (E. S. R., 12, p. 569), spraying with 

 Bordeaux mixture is recommended for its prevention. 



An apricot blight, W. Paddock {Colorado Sta. Bui. 84, pp. 14, ph. 3,fig.'^. 2). — 

 The author's attention was called to a disease of apricots in the fall of 1902, the injury 

 greatly resembling that caused by the common pear blight. A careful examination 

 of the diseased tissues and inoculation experiments showed that the ai)ricot blight 



