DISEASES OF PLANTS. 2(>5 



(lisease<l leaves than in the liealtliy ones. Peroxidase is always more i)revalent than 

 oxidase in the diseased leaves. Catalase seemed present in a majority < it" cases in 

 greater (juantity in the diseased leaves. 



Experiments in the prevention of Peronospora of grapes, F. Zweifler 

 {Wfinlaubc, 1901, No. 15, p. 176; abs. in Ceidbl. Agr. Chein., SO {1901), Xo. 13, pp. 

 818-820). — On account of the high price of copper sulphate, experiments have been 

 conducted with greatly diluted solutions of Bordeaux mixture and with other fungi- 

 cides in com])ating the downy mildew. The author reports upon his experiments 

 made with Bordeaux mixture of strengths varying from 2 per cent down to 0.1 per 

 cent. The results obtained where the vines were sprayed with 0.5, 0.75, an<l 1 per 

 cent .«olut i( ms were equal to those where the 2 per cent solution was used. The grapes 

 were well protected against disease, but where weaker strengths were applied there 

 was undoubted infection. The effect of the stronger solutions on the sugar and acid 

 content of the grapes was quite marked, containing much higher percentages than in 

 the case where weaker solutions were used. Experiments are also reported in wiiich 

 zinc sulphate, manganese sulphate, and alum, in combination with lime and soda, 

 were investigated, Imt these fungicides were all decidedly inferior to Bordeaux mix- 

 ture. The use of the 3 per cent solution of iron sulphate was tried, and when 

 sjirayed twice during July and August the leaves and shoots receiving this mixture 

 were decidedly injured. 



Coulure, or non-setting of grapes, E. H. Raixford {Queensland Atjr. Jour., 

 10 {1902), No. l,pp. 41,42, ph. 2). — This disease, which is known in this country 

 usually by the name of shelling or rattling, is described and is said to occur under 

 two forms — one the failure of the flower to set fruit in any or all parts of the cluster, 

 another in which the fruit sets increase in size for a time, after which they fall off 

 in greater or less quantity. The causes of the disease are said to be accidental and 

 constitutional. The accidental causes are adverse meteorological conditions at flow- 

 ering time, too great vigor of vegetation, and fungus attacks. Each of these causes 

 is described at some length, and hr'wi suggestions given for tlieir prevention so far as 

 means are known. 



The American gooseberry mildew in Ireland, E. >S. Salmon {Jour. Roy. Hort. 

 Soc. [London'], 2G {1902), No. 4, pp. 778, 779). — The first outbreak of the gooseberry 

 mildew {Splixrotheca mors-uvw) was reported in 1900, and in the following year the 

 disease appeared in the same locality and proved more destructive than in the pre- 

 vious season. The conditions seemed to indicate that the' fungus was becoming some- 

 what widely distributed throughout Europe, and the author reconunends spraying 

 the ])lants with a potassium .«ulj)hid solution at 10-day intervals, beginning as soon 

 as the buds begin tn unfold. 



Diseases of the tea plant, G. Delacroix {Jour. Ayr. Trop., 2 {1902), No. 9, pp. 

 67-72).— X list is given, together with brief descriptions cf the principal animal and 

 vegetable parasites which attack the tea plant. Among the insects are various borers, 

 leaf miners, and other leaf-eating insects, scale insects, red spiders, etc. The author 

 also describes attacks of nematodes upon the roots of plants, 2 species ( Tylenchus 

 acutocaudatus and Jleterodera radicicola) being described. Among tiie jjlaut diseases 

 described are the following: Blister blight, due to E.i'ohasidium vexans; anthracnose, 

 caused by Collelotrlclrain cameUiir; gray blight, due to PeMalozziaguepini; thread lilight, 

 caused by Stilbnm nomun; and root rot, due to attacks of RosellinUi. radiciperda. The 

 effect of the alga, ( 'ephaleuroii vire.scen-f, in producing what is known as red rust is 

 described, as well as the attack of a nuni])er of undetermined species of mistletoe 

 upon the plant. 



The parasites of the tea plant, A. Zimmermann {('entbl. Bait. n. Par., 2. Abt., 8 

 {1902), Nos. 1, pp. 16-23; 2, pp. 46-55). — A list is given of animal and plant parasites 

 destructive to the tea plant. Compiled notes are given regarding many species, and 

 a brief bil)liograi)hy is appended. 



