352 EXPERIMENT STATION EECORD. 



A bibliography of the disease, consisting of some oHO titles, is appended. 



The infection of the grape with Plasmopara viticola, H. MtJLLEB-THURGAU 

 {CeniU. BaM. [etc.], 2. AM., 29 {1911), No. 23-25, pp. 6S3-€95, fig. Jf).— The 

 results are given of inoculation experiments with the eonidia of P. viticola on 

 the upper and lower leaf surfaces. In every instance no infection was obtained 

 fi"om inoculating the upper surfaces, while inoculations similar as to time, 

 inoculating material, etc., made on the under side of the leaves were very often 

 successful. 



In the .small dead areas on the older grape leaves large numbers of oospores 

 were found. 



The summer spraying of peaches, J. P. Stewart (Proc. State Hort. Assoc. 

 Perm., 52 {1911), pp. 181-195, figs. 3; Proc. Amer. Pomol. Soc, 32 {1911), pp. 

 281-292, pis. 2). — The results are given of experiments with various fungicides 

 as summer sprays for peach orchards, in which the author notes the meteoro- 

 logical conditions during the experimental period, and the effects of the various 

 sprays on the fruit, foliage, twigs, curculio, scab, brown rot, the carrying 

 quality of the peaches, and on the yield, soundness, and color of the fruit. 



The sprays used were as follows : Self-boiled lime-sulphur, 8 : 8 : 50, plus 2 lbs. 

 of arsenate of lead; lime-sulphur solution, specific gravity 1.003, plus 2 lbs. 

 of arsenate of lead; lime-sulphur solution, specific gravity 1.003, plus 2 pts. 

 of arsenite of lime solution; lime-sulphur solution, specific gravity 1.003, plus 

 2 lbs. of arsenate of lead, applied with a carbon dioxid gas sprayer; Sulfocide, 

 1 : 400, plus 2 pts. of arsenite of lime solution ; Sulfocide, 1 : 400, plus 2 lbs. of 

 arsenate of lead; Pyrox, 5:50; Bordeaux mixture, A : 6 : 50 and i : 6 : 50, 

 plus 2 lbs. of arsenate of lead. The amount of the arsenicals given in each 

 of the above sprays was added to every 50 gal. of the mixture. 



A summary of the spray injuries due to compounds of sulphur and arsenic 

 which developed from the experiments undertaken shows that (1) when used 

 in the proper dilutions most of the injury is due directly to the arsenical but 

 indirectly to the solvent action of the fungicide used with it, (2) that arseni- 

 cals containing soda are unsafe with certain lime-sulphur sprays, (3) that the 

 use of spray water containing appreciable quantities of sodium salts or the 

 use of commercial lime-sulphurs to which sodium or potash salts have been 

 added is especially dangerous in connection with arsenicals, and (4) that to 

 avoid lime-sulphur-arsenic spray injury, so far as it depends on the materials 

 themselves, it is necessary to eliminate the solvent action of the fungicide 

 by putting it out of solution, coupling this with the use of an arsenical of the 

 highest grade. 



It was found that the fungicidal properties of the lime-sulphur spray were 

 not lost by the precipitation of the sulphur when the spray was applied with 

 the gas sprayer. In the control of curculio the arsenate of lead was not very 

 effective while the arsenite of lime was remarkably so. 



Incidentally, the author notes the practical control of curculio on apple 

 trees, even when the first application of the arsenicals was from 10 to 15 days 

 after the petals had fallen and the second some 3* weeks later. 



All of the sprays except one (Sulfocide plus arsenate) increased the yields, 

 and all gave a greater percentage of sound fruit than the unsprayed trees, 

 ranging from as low as 53.1 per cent of sound fruit for the Sulfocide and 

 arsenate sprays to 73.9 per cent for the i : 6 : 50 Bordeaux mixture as compared 

 with an avei-age on the 2 checks of about 10 per cent of sound fruit, while the 

 lime-sulphur and arsenate mixture applied with the carbon-dioxid gas sprayer 

 gave 73.6 per cent of sound fruit. The effects of the spray on scab and brown 

 rot varied considerably, ranging from 22.8 per cent of scab for the Sulfocide 

 and arsenite to 6.57 per cent for the self-boiled lime sulphur and arsenate 



