DISEASES OF PLANTS. 651 



2. ser., 3 (1009). pp. 283-307; t^iuz: l^prr. A<ir. ItnL, f,3 (1910), No. 2, pp. 185- 

 209). — After a brief discussion of the opinions of various investigators on this 

 quesrion, the author concludes from his experiments and observations that the 

 greater resistance of the American grape and of other plants to tlie attacks of 

 Oidium, Perouospora, and gall mites is due to the relative wildness and conse- 

 quent abundant acidity of these plants as compared with corresponding varieties 

 which have been for years in a high state of cultivation. It is claimed that 

 this greater initial resistance is only temporary and will gradually disappear 

 under the more or less intensive culture to which the vines will be subjected 

 year after year. 



Experiments with various sprays in combating the downy mildew (Pero- 

 nospora viticola) of the grape, A. Bretschneider (Ztsrhr. Laiulw. Vcrstuch^tir. 

 Ocstcrr., 13 (1910), No. 3, pp. 135-l-'i8). — In the experiments conducted the fol- 

 lowing sprays were used : 1 per cent Bordeaux mixture as a standard for com- 

 paring the efficiency of the other sprays; 1, 1.5, and 2 per cent solutions of the 

 trade compound Tenax, which is a soda-copper spray in which part of the copper 

 sulphate has been replaced by aluminum sulphate; Cucasa, a saccharine Bor- 

 deaux mixture of normal strength ; 2 and 3 per cent copper-sulphate-formalde- 

 hyde mixtures; and 1 and 2 per cent solutions of a trade compound known as 

 rational hydro-copper salt fungicide. The composition and preparation of each 

 spray is given, while the number of applications, dates of spraying, and the 

 results for each mixture are set forth in a table showing the comparative 

 results at four widely separated localities. 



A careful study of the effects of the sprays on the mildew gave the following 

 results : The formaldehyde, copper-sulphate-formaldehyde, and hydro-copper 

 salt solutions each proved of little value as a fungicide, and the two last named 

 injured the plants; both the Tenax and Cucasa controlled the mildew with no 

 appreciable injury to the vines, and may therefore be considered of value in 

 combating this disease. 



Experiments on the apple with some new and little-known fungicides, 

 M. B. Waite ([/. S. Dept. Agr., Bur. I'lntit Indus. Circ. 58, pp. 19). — A prelimi- 

 nary report is made on some experiments with 9 different fungicides in connec- 

 tion with a study of the spray injuries to apples caused by Bordeaux mixture. 



The main experiment (series 1) was carried out at Winchester, Va., during 

 1009, and was supjilemented by simil.-ir tests on 3 other orcliards. Three varie- 

 ties of ap]>les were used, viz, Ben Davis. Yellow Newton, and York Inii)erial. and 

 they were divided into 11 plats, as follows: (1) Control, nnsprayed ; (2) standard 

 Bordeaux mixture (3:3:50); (3) iron Bordeaux mixture (Bordeaux mixture, 

 3 : 3 : 50 plus 2 lbs. of iron sulphate) ; (4) standard Bordeaux mixture plus gyp- 

 sum (3:3: .50 plus 3 lbs. of gypsum) ; (5) standard Bordeaux mixture (3 : X : 50, 

 X equaling the lime added until the neutral point was reached as shown by the 

 litmus test); (6) self-boiled linu'-sulphur mixture (10:10:50); (7) "copper 

 suli)hid mixture No. 1" (self-boiled lime sulphur 10:10:50, plus 2 lbs. of cop- 

 per suli)hate) ; (8) " copper sulphid mixtiu-e No. 2 " ( Bordeaux mixture 3:3: 50, 

 plus 1 gal. of commercial lime-sulphur solution) ; (9) "iron sulphid mixture" 

 (self-boiled lime sulphur 10:10:50. i)lus 3 11)S. of iron sulphate: (10) arsenate 

 of lead (used alone), 2 lbs. to 50 gal. : .ind ( 11 ) control, nnsprayed. 



To each of these fungicides 2 lbs. of arsenate of lead in the form of i)aste 

 was added to every .50 gal. of spray mixture The sprays were applied with an 

 ordinary hand liarrel pump first on .May 11 and 12, shortly after the petals had 

 fallen iind while the calyxes were si ill open. The secon<l application was made 

 June 11 and 12, and the third .July 10. 



All the fungicides jirotected the trees almost compli'tcly frnm fungus diseases, 

 and since the arsenate of lead was combined with them they also controlled 



