DISEASES OF PLANTS. 343 



Influence the time required for the spores to germinate, but such factors as 

 evaporation, surface tension, and diffusion of the drop containing the conidia 

 did not influence the percentage of germination. It was found that chilling had 

 a marked effect on the degree of infection secured, and it is thought that this 

 condition is an adaptation of the fungus to its environment. A fall of tempera- 

 ture which leads to the deposition of dew provides a favorable medium in which 

 the zoospores may develop. The experiments showed a close relationship be- 

 tween susceptibility and host vigor in that healthy plants were found to be more 

 susceptible than sickly or abnormal ones. 



Repeated infection experiments with conidia from the common radish were 

 made, and no marked differences in susceptibility in varieties of radishes were 

 observed. Other species of cruciferous plants were investigated, and infection 

 was secured with white mustard and cabbage, but at no time was it possible 

 to secure more than 50 per cent of infections of white mustard and still less 

 for cabbage. No infection could be secured on any of the other crucifers tested. 

 These included turnips, black mustard, ruta-baga, shepherd's purse, garden 

 cress, wild pepper grass, hedge mustard, candytuft, water cress, and wall 

 flowers. 



A bibliography is appended. 



Root knot and its control, E. A. Bessey (TJ. 8. Dept. Agr., Bur. Plant Indus. 

 Bui. 211, pp. S9, pis. 3. ffgs. 3). — This bulletin gives the results and conclusions 

 of studies made by the author on root knot due to Heterodera radicicola, which 

 is widespread throughout warm temperate and tropical zones of the world, and 

 is especially prevalent in this country in the South. It also occurs in the North- 

 ern States, and is a serious disease of greenhouse plants everywhere. 



The author records about 4S0 species and varieties of plants subject to the 

 attacks of this nematode, and describes the life cycle, conditions under which it 

 multiplies, and how it attacks the plant. Under methods of control in green- 

 houses and seefl beds the author describes sterilization by heating with steam, 

 removal of infested soil, destruction of nematodes by freezing, thawing, and 

 drying, and the use of formaldehyde. For the control of nematodes in the 

 field more difiiculty is experienced, but where perennial crops are to be planted, 

 preliminary to setting them, the ground may be freed by the use of carbon 

 bisulphid or flooding. Where these measures can not be used high fertiliza- 

 tion and constant cultivation will help the plants to outgrow the trouble. Where 

 the laud is devoted to annual crops, keeping it free from vegetation for 2 

 years, planting nonsusceptible crops, heavy use of fertilizers, flooding the land 

 for a period of several weeks, and protecting the infected land from washing 

 by the erection of embankments, ditches, etc., are advised. 



An extensive bibliography is appended. 



A Sclerotinia on apple, J. B. Demaree (Science, n. ser., 35 (1912), No. 889, 

 pp. 77, 78). — ^A description is given of apothecia of Sclerotinia found upon mum- 

 mied apples in November, 1911. The fruiting bodies differed materially in 

 some respects from those described by Aderhold as associated with Monilia 

 fructigena on the apple, and the author presents contrasting characters show- 

 ing that in nearly every respect the Sclerotinia described is smaller than that 

 mentioned by the German investigators. 



The author was unable to produce any growth from the ascospores; there- 

 fore there is no proof of any connection with a conidial form of Sclerotinia, but 

 it is supposed to be the perfect form of the fungus causing the brown rot of 

 apples in this country. 



On the chloranthy of Prunus mume caused by Caeoma makinoi, S. Kusano 

 iJour. Col. Agr. Imp. Univ. Tokyo, 2 (1011). No. 6, pp. 287-326, pis. 2, figs. 3).— 

 An account is given of the fungus C. niakmoi and its action upon the host. The 



