DISEASES OF PLANTS. 151 



which sprayiiifj; with potassiiiui sulphid is advised ; a disease of sweet potatoes, 

 due to Fiisariion sp., which results in a wilt of the plants; and a disease of 

 apples, to which the name apple scurf is given. This apple disease is of fungus 

 ori.irin, although Jhe species has not been determined. It affects the bark, caus- 

 ing the appearance well described by the name given, and the characteristic 

 malformations have been repeatedly formed through inoculation experiments. 



The tobacco wilt is said to be the most important of the diseases luider inves- 

 tigation, and for its control the author has conducted experiments in soil treat- 

 ment as well as in the breeding of resistant races. A large number of chemical 

 substances were used in attempts to destroy the fungus in the soil, without 

 results that would be considered satisfactory in oi-dinary use. During the 

 progress of these investigations the susceptibility of a considerable number of 

 plants to this fungus was tested, and It was found that Irish potatoes and toma- 

 toes were subject to a disease which in all appearances was like the tobacco 

 wilt. Specimens of eggplant and peppers were similarly affected, but the iden- 

 tity of the diseases on these plants with tobacco wilt is not fully established. 

 Experiments with the electric current for sterilizing the soil were undertaken 

 without beneficial results. The most promising means of overcoming the Gran- 

 ville tobacco wilt is believed to be in the bi'eeding and selection of resistant 

 varieties or races. A considerable number of these have been experimented 

 with and marked differences in susceptibility to disease are noted. 



Notes on the watermelon wilt, and a brief account of experiments in breeding 

 by selection and hybridization for resistant varieties are given. These latter 

 experiments were in cooperation with the Bureau of Plant Industry of this 

 Department. 



The root-rot fungus, :m. C. Cooke {Ganl Chroii., 3. scr., J,l (1007), A'o. 1067, 

 p. 361, pg. 1). — x\ttention is directed to a disease due to Tliiclavia hasicola, 

 which attacks indiscriminately a great variety of cultivated plants, the account 

 being largely drawn from the report of the Connecticut State Station for 1906 

 (E. S. R., 18, p. 1138). According to the author this fungus has been reported 

 on peas, horse-radish, cyclamen, lupines, tobacco, sainfoin, senecio, violets, aralia, 

 and nemophila. It is shown that the fungus, which is usually saprophytic. 

 l)ecomes under favorable conditions an aggressive parasite. 



Take-all and its control, G. II. Robinson {Jour. Dcpt, Agr. Victoria, ,7 

 (1!)07), Xo. -'i, pp. :^53~2')6}. — A description is given of the disease known in 

 Australia as take-all, which is due to the fungus Ophiobohis f/rominis. For the 

 control of this disease rotation of crops, burning over of badly affected stubble, 

 early fallowing, and the substitution of crops not liable to disease are recom- 

 mended. 



Diseases, and injuries to beets in 1906, R. Schander (B1. Ziickcrriibcnbau, 

 l.'f {1007), No. 8, pp. 113-119). — The sunnner of 1900 is said to have been espe- 

 cially favorable to plant diseases in West Prussia, and brief accounts are given 

 of the more important fungi and insects observed as attacking beets. Among 

 the more important ones described are the beet-root rot {PJionia bct(c), a dry 

 rot, and a rot due to Rhizocfoiiia violacea, which were especially destructive. 

 Beet scab and the leaf spot caused by JJromyces betcc were not very prevalent 

 and the bacterial black rot was not observed. Among the more troublesome 

 animal pests were nematodes, wireworms, field mice, etc. Suggestions are 

 given for the control of all the serious pests. 



The zonal beet scab, A. Stift {Bl. Zuckcrriibcnbau, I'f {1907), No. 10, pp. 

 lo]-lo3). — A description is given of a form of beet scab that from its habit of 

 girdling the root is called zonal scab. This disease has l)een attrilmted by 

 different authors to various causes, one claiming that it is caused b.v attacks of 

 minute worms, species of Enchytneidte, followed by Oospora sp. (E. S. R., 10, 



