DISEASES OF PLANTS. 157 



season the supply of water is restored and the orchard irrigated, with tlie result that 

 in many instances distinct second growth is made which is inunature when winter 

 sets in, and the branches are either killed outright or severely injured. Second 

 growth is not always necessary for the appearance of the disease, as was shown by 

 examinations in a number of orchards. The soil is estimated to contain 1,820 lbs. of 

 common salt per acre, taken to a depth of 1 ft. In addition, sodium carbonate is 

 very abundant, and it is probable that these alkalis exert an injurious effect upon the 

 trees. Attention should be paid to the nature of the soil where the orchards are 

 planted, and irrigation water should be judiciously used to prevent the occurrence of 

 the disease. A number of instances are cited in which the Ben Davis apple suffered 

 severe injury due to applications of Bordeaux mixture. It is thought probable that 

 it will be necessary to modify the formula commonly recommended for spraying 

 trees of this variety. 



The })Iackberry-root disease, due to Rhizoctonia sp., has proved quite destructive 

 about the station. There appears to be no cure for the disease, and the destruction 

 of all affected plants is recommended as a preventive measure. 



The occurrence of the asparagus rust {Puccinia asparagi) is mentioned. Asters 

 planted in the college campus are said to have been almost entirely destroyed 

 by attacks of species of Fusarium. This fungus seems to have been jiresent in the 

 soil, and it is recommended that the beds be removed or the soil replaced with fresh 

 earth. 



The pea-root disease proved one of the most destructive of the diseases under 

 investigation during the season rej^orted upon. The author's attention was first 

 called to it in September, 1900. During the following winter soil from infected fields 

 was secured and greenhouse experiments conducted with it. Plants in the soil were 

 nearly always attacked by fungi on the roots and stems below ground, and although 

 attempts to cultivate the fungus artificially failed, the distinctive characteristics 

 showed that it belonged to the genus Rhizoctonia. A potato disease due to Rhizoc- 

 tonia sp. was under investigation at the same time, and inoculation experiments 

 were undertaken with the potato organism. While the experiments did not prove 

 conclusively that the Rhizoctonia disease of potatoes was the cause of the trouble 

 with peas, the indications pointed strongly to this conclusion. For the jirevention 

 of the potato disease and the stinking snuit of wheat treatment with corrosive subli- 

 mate or formalin solutions is recommended. 



Report of the botanists, G. E. Stone and R. E. Smith {Massachusetts Sla. Rpt. 

 1901, pp. 57-85, Jigs. 3). — During the season covered by the report a number of 

 species of fungi affecting shade trees have been observed. Among these are the 

 Ghwsporium nervisequum, which caused the partial defoliation of the white oak 

 throughout the State, Glceosporiuvi sp. on maple and sycamore, Dothidea ulmi on 

 elm, and Cercospora microsora on the European linden. The dying of cut-leaved 

 birches was quite prominent in the eastern part of the State during the summer. 

 The cause of the trouble was incidentally due to borers, but it is thought that the 

 drought of the previous season was the primary cause of the trouble. 



The chrysanthemum rust, which was first noticed in the State in 1896 and has 

 since extended over a large portion of the United States, is considered at some 

 length. The disease was most prevalent in 1897 and 1898, and during the past 3 

 years has shown a marked tendency to decrease. Various remedies have been tried 

 by different growers, and the practice of inside culture during the summer has 

 proved very beneficial in obtaining plants free from rust. Most growers now con- 

 sider the chrysanthemum rust of little consequence, and, so far as the authors' 

 observations go, the proper remedies lie in the judicious selection of healthy rust-free 

 stock and inside cultivation. 



The practice of desiccation, or drying of greenhouse soils by the aid of the heat of 

 the smiimer sun, has been followed for some time to observe the effect of such treat- 



8994— No. 2—02 5 



