DISEASES OF PLANTS. 153 



the use of iwtatoes for seed on which small black sclerotia (Rhhoctonia solani) 

 are found (best seen when the skin of the potatoes is moistened, and (2) re- 

 fraining from planting potatoes for from 2 to 3 years on land on which potatoes 

 nave grown which show a white covering on the stem (H. solani) or black 

 sclerotia on the tubers, or on land directly adjoining such fields. 



Infection experiments with Phytophthora infestans, L. Gakbowski (Centbl. 

 Bakt. [etc.'l, 2. Aht., 36 (1913), No. 19-25, pp. 500-508, pi. i).— In the effort to 

 find a nutritive medium of Icnown composition for the study of pure cultures of 

 P. infestans, the author experimented with infection material from potatoes in 

 decoctions of several closely related plants, also in various solutions of definite 

 chemical comiwsition. It is stated that Knop's solution with addition of glucose 

 fulfils the requirements of such medium for P. infestans. 



Pests and diseases of sugar beets, 1912, O. Faixada (dsterr. XJngar. Ztschr. 

 Zuckerindit^. a. Landw., Ji2 {1913), No. 1, pp. 19-33). — In addition to brief dis- 

 cussions of weather conditions and insect injuries, the author gives the results 

 of observations on various injuries, diseases, etc., of roots and leaves. Cercospora 

 beticola was found in connection with leaf spots. The so-called frog spawn 

 fungus (said to include Leuconostoc mesenterioides and Clostridium gelatino- 

 suni) takes considerable sugar from the- sap in the formation of its character- 

 istic zoogloea, which was studied under various conditions. 



Boot tumors, A. Stiff (Osterr. XJngar. Ztschr. Znckerindus. u. Landw., Jf2 

 (1913), No. 1, pp. 9-18, figs. 6).— Previous work (E. S. R., 27, p. 544) having shown 

 that two forms of beet tumor exist, one having slight connection and designated 

 as ligature tumor and the other having closer connection and designated as an 

 outgrowth, experiments were instituted to ascertain the chemical differences 

 between each form and the main body of the beet. The results were very 

 variable and unpromising. 



A dry rot of sweet potatoes caused by Diaporthe batatatis, L. L. Habtkb 

 and Ethel C. Field [U. S. Dept. Agr., Bur. Plant Indus. Bui. 281, pp. 38, pis. Jf. 

 figs. //). — A description is given of a dry rot of sweet potatoes, attention to 

 which was first called by Halsted (E. S. R., 2, p. 416). In this publication the 

 trouble was attributed to a pycnidial stage of the fungus, described as Phoma 

 batatw. The authors have succeeded in isolating the ascogenous form of the 

 fungus and have given it the name D. batatatis n. sp. (E. S. R., 28, p. 548). 



The disease is said to be principally a storage trouble, and is characterized 

 by a drying and shriveling of the potato. It also occurs in the hotbed and in 

 the field, although the organism is not a vigorous parasite and consequently 

 under ordinary conditions does not become evident until some time after har- 

 vesting. 



The different stages of the fungus have been investigated and both were de- 

 rived from the same isolation. Inoculations with pure' cultures of the pycnidial 

 stage have proved successful both in the greenhouse and in the field, and suc- 

 cessful infections were obtained from reisolations. 



The diseage is believed to be disseminated principally by means of the seed 

 and by the use of decayed potatoes for manure. Diseased potatoes should be 

 cooked before feeding to stock and should never be scattered on the field as a 

 fertilizer. Seed beds should be sterilized and potatoes to be used for seed care- 

 fully selected. 



Apple tree anthracnose, H. S. Jackson (Oregon 8ta. Bien. Crop Pest and 

 Hon. Rpt. 1911-12, pp. 178-197, figs. 9). — This is a preliminary report on a 

 study of the apple tree anthracnose, formerly attributed to Glceosporium mali- 

 corticis (E. S. R., 12, p. 58). The life history of the fungus is traced at length, 

 and the perfect form described under the name Neofabrwa malicorticis (E. S. R., 

 27, p. 649). 



