DISEASES OK PLANTS. 163 



meii!^, showing that this method can not be relied upon to secure inimnnity from 

 attack. 



Spraying potatoes, W. T. Macoun ( Canada Expt. Farms Rjits. 1902, pp. 117- 

 120). — -During the season covered by the report experiments were carried on to com- 

 pare the vahie of Bordeaux mixture, either in connection with Paris green or with- 

 out, and a patented fungicide and insecticide known as Bug Death. The comparative 

 efficiency of the different treatments is shown, from which it appears that Bug Death 

 is not nearly as economical for use as is Bordeaux mixture, with or without Paris 

 green. In 9 out of 11 tests the yield, where Bordeaux mixture and Paris green were 

 sprayed over the plants, Avas considerably greater than where the other fungicide was 

 used. There is no evidence to show that Bug Death has any value as a plant food, 

 as is claimed, and vines which had received this preparation were no more vigorous 

 than those sprayed with Bordeaux mixture and Paris green. 



The effect of black rot on turnips, E. S. Smith ( U. S. Depf. Agr., Bureau of 

 Plant Indmlry Bui. 29, pp. 20, pis. 14) ■ — This bulletin consists of a series of photo- 

 micrograjihs, accompanied by an explanatory text, and is in continuation of the pre- 

 vious papers published by the author on this disease (E. S. R., 9, pp. 847, 849). In 

 this paper attention is confined to the action of the parasite on the host plant, the 

 previous discussions treating of the morphology and cultural peculiarities of the 

 parasite. So far as the author is able to determine, the organism causing the l)lack 

 rot is capable of dissolving the cell wall proper, and this action is progressive, as 

 shown by the fact that many of the cell walls observed in the infected portion of the 

 plant are only one-third to one-fourth as thick as the walls of adjacent uninjured 

 cells. The action is probably enzymatic and proceeds rather slowly. 



Fungus diseases and other injuries, W. T. Macoun ( Canada E.fpt. Farms Rpts. 

 1902, pp. Ill, 112). — ^Brief notes are given on the occurrence of the sooty fungus or 

 fly-sjieck fungus of apples, which is caused by Lepiothyrium piomi, a rusting of apples 

 which is attributed fo improper spraying, a serious defoliation of trees, the cause of 

 which was not definitely determined, and the black rot of cabbage. Notes are given 

 on the preparation and use of fungicides and the value of these, particularly Bordeaux 

 mixture, in controlling certain plant diseases. 



Report on fungus diseases on cultivated fruits, F. W. Fa urot( if tssoun Fruit 

 Sta. Bid. 6, pp. 24, figs. 9). — Illustrated descriptive notes are given of a numbei; of 

 fungus diseases observed during the season of 1902 as affecting apples, peaches, pears, 

 plums, grapes, blackberries, and raspberries. Directions are given for preventing 

 the occurrence of these diseases, so far as known, together with the results of the 

 author's observations and experiments. 



Fungus diseases of the apple, pear, and quince, F. L. Stevens [Nortli Caro- 

 lina Sta. Bui. ISo, pp. 64-82, figs. 10). — Popular (lescriptions are given, with sugges- 

 tions for prevention, of apple scab, apple rust, rij)e rot, apple canker, black rot, and 

 powdery mildew of the apple; fire blight, anthraimose, rust, canker, scab, and leaf 

 spot of pear; and quince rust, fire blight, and fruit spot. 



On scab and mildew of fruit trees, and methods of combating these dis- 

 eases, J. Eriksson (A'. Laudt. Akad. ILnidl. och Tidskr.,42 {1903), No. 1, pp. 58-71, 

 j)l. l,figs. 10).~T\\ii diseases described are apple-tree sc-ab ( Venturiadendrilica), pear- 

 tree scab {V. pi/rina), and mildew of fruit trees {Monilia fructigena). For com- 

 bating the scab diseases the author recommends immediate removal and destruction 

 of fallen leaves from affected trees, and spraying or washing the bare trees with Bor- 

 deaux mixture or copper sulphate solution. In addition to this winter treatment, 

 2 or 3 sprayings during the spring and summer are advisable. The remedies 

 advocated for combating Monilia are to gather and burn all rotten or dried-up fruit. 

 On trees which have shown indications of disease all dried-up flower clusters are 

 removed before the following spring and the diseased parts are cut off and burned. 

 Affected trees, particularly the young branches, shouhl be sprayed at the beginning 



