§78 EXPERIMENT STATION RECORD. 



if neglected would probably prove serious in the nurseries. The treatment of 

 the plants with Bordeaux mixture and the removal of the dead leaves are 

 recommended. 



The effect of different soils on the development of the carnation rust, J. L. 

 Sheldon (Bot. an:.. \0 (1905), No. 3, pp. 225-229). — The author reports the 

 results of investigations to determine the effect of different kinds of soil on 

 the development of the carnation rust. Previous inoculations of asparagus, 

 onion. Dianthus, and Gypsophila with asparagus and carnation rusts seemed 

 to indicate that the conditions which were favorable for the development of 

 the host were also favorable for the development of the rust. 



In the experiments reported upon a considerable number of inoculations were 

 made on asparagus and Dianthus. in which plants of different ages were used 

 and kept in the greenhouse under control from other infection. The results 

 show that the plants that were making a vigorous growth were more sus- 

 ceptible to artificial infection than those that were making no apparent growth. 

 Some carnations which were inoculated 5 or 6 times at intervals of 20 days 

 did not show any trace of disease. These plants had grown very slowly, were 

 slender, and produced only 1 or 2 small blossoms. 



The varying susceptibility of varieties of carnations to rust is commented 

 upon, and the author notes the difference in the period of incubation of the 

 rust on the green and glaucous-leaved species which were inoculated at the 

 same time. 



A lack of susceptibility to inoculation is reported for seedling onions inocu- 

 lated with the asparagus rust. These inoculations were made as soon as the 

 seedlings appeared above ground and were repeated at frequent intervals 

 until the seedlings were two months old. After this time almost every inocu- 

 lation was successful. 



The author attributes the failure on the part of other investigators to a lack 

 of susceptibility of the host at the time the inoculation was made, and not to a 

 failure of the spores to germinate or to the way the inoculation was made. 



As a means of testing the effect of different soils on the period of incubation 

 of the rust, a green-leaved pink which was known to be susceptible to carnation 

 rust was selected. Rooted cuttings were planted in 5 different kinds of soil, 

 ranging from almost pure sand to soils containing little sand, being made up 

 mainly id" organic matter and clay. The plants were arranged in series, and of 

 170 plants inoculated only o failed to show rust pustules in 16 to 21 days, the 

 majority showing in IT to 19 days. 



The author summarizes the results of his investigation, the details of which 

 are to be published later, stating that the intensity of color in the plants was 

 directly proportional to the amount of clay in the different soils. The growth 

 of the host was directly proportional to the amount of organic matter, nitrogen, 

 and silt in the different soils. The period of incubation of the carnation rust, 

 while not uniform in every instance, was in general inversely proportional to 

 the amount of organic matter, nitrogen, and silt in the different soils, and to 

 the growth of the host: it was directly proportional to the amount of gravel 

 and sand in the different soils. Those soils that were found favorable for the 

 development of the host plant also favored the development of the rust, namely, 

 those containing the most organic matter combined with silt and clay and a 

 small amount of sand — soils which had a high-water retentivity and which 

 were rich in nitrogen. 



A new parasite of oxalis, L. Tbabut {Bui. Apr. Ahjrrle ci Tunisie, 11 

 (1905), No. 8, pp. 1GS, 169). — According to the "author a number of species of 

 ornamental oxalis were observed parasitized by the broom rape (Phelipcea 



