DISEASES OF PLANTS. 1057 



Tlu- Sclemtinm disoase, which is due to an undeHcrihed species, has been very prev- 

 alent, tlie funfrns attackin^r the fruit and vines, rpright-growinf; i)arts of plants are 

 not affected, the disease seenii;i^ to attack those portions \u contact with the 

 ground. Upon the fruit the attack is very noticeal)le, the first sign of the presence of 

 the disease being a slight rotting on the underside of the melon, followed by the 

 formation of a white fringe of fungus mycelium surrounding the whole fruit. This 

 disease is difficult to control, but it is thought destroying affected i)lant8 and sj»raying 

 the vines and ground with Bordeaux mixture will give relief. 



The lettuce drop has proved quite destructive in some localities. The immediate 

 cause seems to be the fungus Sclerolhiia libcrtiava. ' The fungus is both an active and 

 a facultative para.site and spreads with great rapidity. Owing to the lateness of its 

 appearance, no experiments were conducted for its control, Imt subirrigation, removal 

 of the disease<l ]>lants, ami spraying are suggested as possible remedies. 



The strawl)erry blight {Sphnirlld frdfjdri.r) exists on the strawberry i)lants through- 

 out the year, so that there is no necessity for the production of winter spores. For 

 the j)rotection of the j)lants thorough and repeated sprayings with fungicides are 

 reconnnended. Marked differences are reported in the susceptibilty of different 

 varieties, and a brief list is given of varieties which appear nearly free from disease 

 an<l those which are t)a<lly affected. 



Notes on some plant diseases, \V. Lochhead ((hildrln Ai/r. Col. mul Expt. Farm 

 Rpt. lUOl, pp. JO-jo, tifjx. 6). — The life histories of grain rusts and the black rot of 

 grapes are given, ami suggestions offered for their jirevention so far as i)ractical means 

 are known. 



The more important fungus diseases of cultivated plants and means 

 for their prevention, K. Hotter (Die icichfigsirn PUzkrankhriteii der Iniufirirtlixrhrift- 

 liclicii Ct(/tiirgcirarhst' ui id if ire Bekampfung. Gratz, 1900, pp.60, figx. 48). — x\fter dis- 

 cussing plant diseases in general and their distribution and amount of injury caused 

 by them, a description is given of the structure and development of fungi, their life 

 history, relation between the fungus and host plant, etc. The fungus diseases are then 

 taken up and briefly described, being grouped together according to their relation- 

 ships. Suggestions are given for the prevention of these diseases and a chapter is 

 devoted to a discussion of the value of Hordeaux mixture as a fungicide. 



Some Helminthosporium species and the diseases produced by them on 

 barley and oats, K. P. Ravn {Vgeskr. Landm., 4& (1901), No. 18, pp. 1!)2-194). . 



A "foot" disease of cereals, (i. Delacroix {Exir. from Bid. Sor. Mgcol. France, 

 17 {1901), No. .2, pp. 9, figa. 2). — A description is given of the fungus Ophinfiohm 

 gr(imini.'< which is parasitic upon various cereals, attacking them in the lower inter- 

 nodes and causing the stems to fall over in a way sinular to that produced by the attacks 

 of the Hessian fly. Mangin has concluded that this disease was ' rimarily due to Lepto- 

 sphscrid lierpoiriclioidex and that the Ophiobolus is of secondai_, importance ( E. ^. 

 R., 10, p. 650). The author gives an account of a number of experiments in which 

 wheat was grown in pots that were infested with spores and the stubble of wheat 

 plants attacked ]>y both fungi. In comparing the results obtained by hiscidtures he 

 found that both fungi produce the same condition and that the density of planting 

 influences to a great degree the gravity of the disease. When sown thickly the foot 

 disease is of much greatt^r importance in causing the plants to lodge. Notes are given 

 in conclusion on the germination of the spores of Oj)hiobolns grami)ii.f, and its 

 perethecial stage is described. 



The downy mildew of grasses, V. Pe<;i,iox {Stnz. Sper. Agr. Ihd., 34 (1901), No. 

 o-O, pp. '>0>;-'i.l.', plx. .y). — An extended study is given of Scleroxporo grdininicoln, a 

 fungus nearly allied to Peronospora. The fungus was for a nundier of yeai-s only 

 known as occurring upon sjjecies of Setaria, but the list ol host plants as given by the 

 author includes wheat, oats, Areiid faliid, couch grass, canary grass, perennial rye 

 grass, and ree<l grass; and it probably occur.- on redtop, creeping soft grass, reed 



