DISEASES OF PLANTS. 547 



organism, particularly studying tbo possible relationship of the Cladosporium 

 and the Phouia. 



As a result of their investigations, the authors found that P. tabifica in their 

 cultures never produced any eonidial forms and that the Cladosporium occur- 

 ring on the young leaves did not result in a Phonia form. This is held to indi- 

 cate that the two fungi are quite distinct, and it contiruis the ob.<ervations 

 previously made that there are two distinct diseases, one being caused by Clado- 

 sporium attacking the young leaves, while the true heart rot is a result of the 

 presence of P. tabifica. 



The root rot of cassava, E. de Kruijff (Teysmannia, 21 {1910), No. 3, pp. 

 Uil-lJiO). — For several years cassava plants in Tasmania have suffered from 

 a root rot which causes the plants to shed their leaves and the tubers to rot slowly. 

 In the first stages of the disease the epidermis of the tubers turn a violet red. The 

 tubers then begin to rot at the tips, but often some of the tubers on a diseased 

 plant may remain entirely healthy. The diseased plants do not die, but later 

 in the year form new leaves and tubers. 



A microscopic examination of the diseased tissues showed the presence of 

 small bacteria which in pure cultures resembled in many points certain lactic 

 ferment bacteria. Inoculations of healthy plants with the isolated bacteria and 

 also with raw material from diseased tubers were made, but gave only negative 

 results. Old and young plants are alike attacked and irrespective of the weather 

 conditions, for the disease is as severe in wet years as in dry. 



Favorable results in checking the disease were obtained by the use of lime on 

 the soil. More resistant varieties from other regions are also suggested as a 

 possible remedy. 



Diseases of cotton, C. Maubi.anc {Agr. Prat. Pays Chauds, 10 (1910), Nos. 

 83, pi>. 105-1 11, pi. 1; So, pp. 295~30.'f). — An account is given of some of the 

 more important diseases of the cotton plant, among those described being cotton 

 wilt, root rot, damping off, Phoma and Fusarium diseases, angular leaf spot, 

 and boll rot. The data are largely drawn from publications of this Department 

 and of some of the experiment stations in this country. 



Tests of spray mixtures for Alternaria blight of ginseng, H. H. Wiietzel 

 and W. H. Rankin (Spec. Crops, n. scr., 9 {1910), No. 93, pp. 327-329. figs. /,).— 

 Attention is called to the frequent complaint of a failure of Bordeaux mixture 

 to protect ginseng against the Alternaria blight, and an investigation has been 

 conducted to determine the effect of different fungicides on the germination of 

 the spores of the fungus causing the disease. In these experiments about 20 

 different fungicide mixtures, together with Paris green, sulphur arsenate, and 

 other insecticides were tested. 



In comparing the germination results it appears that the fungicides most 

 effective against the Alternaria were full and half strength Bordeaux mixture, 

 Bordeaux mixture and Paris green, Paris green and milk of lime, Paris green 

 alone, milk of lime, suli)hur arsenate,, and possibly a lime-suli)hur mixture 

 applied as a summer spray. The Paris green and milk of lime, alone and in 

 combination, seem to be promising unless for some reason they should prove 

 injurious to the ginseng plant. The effectiveness of the Bordeaux mixture was 

 so complete that the addition of Paris green had no evident advantage. 



In conclusion the authors recommend the use of Bordeaux mixture, to which 

 Paris green may be added, and advise against the use of new mixtures which 

 have not been fully tested. 



The onion eel worm, W. Laidlaw and C. A. Price {Jour. Dcpt. Agr. Victoria, 

 8 {1910), No. 3, pp. 103-111. figs. .>).— I)escri|)tions are given of exi)eriments for 

 the eradication of the eel worm {Tylenchus dcva^tatrid), which has proved very 



