EXPERIMENTS IN THE CONTROL OF GRAPE ANTHRACNOSE. 5 



The following fungicides were tested in the experiments: 



(1) Iron sulphate, 13J pounds; sulphuric acid (commercial), 7 ounces; hot water, 

 3} gallons. 



(2) Iron sulphate, 6| pounds; sulphuric acid (commercial), 3^ ounces; hot water, 

 3| gallons. 



(3) Sulphuric acid (commercial), 10 per cent solution. 



(4) Sulphuric acid (commercial), 4 per cent solution. 



(5) Commercial lime-sulphur solution (1-10). 



(6) Self -boiled lime-sulphur solution (8-8-50). 



(7) Bordeaux mixture (4-3-50). 



(8) Bordeaux mixture (4-3-50) with 2 pounds of rosin-fishoil soap added. 



The mixtures were prepared as follows: 



For the iron-sulphate mixtures the required amount of crystallized 

 iron sulphate was placed hi a wooden tub and treated with the proper 

 quantity of sulphuric acid. The boiling water was then added and 

 the mixture stirred until the iron sulphate was all in solution. The 

 mixture was used immediately after preparation. 



The sulphuric-acid solutions were made by adding the requisite 

 quantities of the acid to the water hi a wooden tub and stirring. 



The concentrated lime-sulphur solution was prepared by mixing 

 1 gallon of commercial lime-sulphur solution, 32.8° Baume, with 9 

 gallons of water. 



The self-boiled lime-sulphur mixture was prepared as recommended 

 by Scott. 1 



The Bordeaux mixture and the Bordeaux mixture with soap added 

 were made in the usual way. 



Mixtures Nos. 6, 7, and 8 were used only as summer sprays, while 

 the others were applied only to the dormant vines. 



The vines in all the plats were pruned carefully each season during 

 which the experiment was in progress. All the canes on which the 

 disease could be readily recognized were cut away, and the primings, 

 together with the dead leaves and other debris, were removed from 

 the vineyard and burned. 



Plats Nos. 1, 2, 4, and 5 were treated before the buds opened, as 

 shown in Table I. In applying the mixtures to these plats it was 

 considered inadvisable to use a sprayer, because of the effect of the 

 sulphuric acid in mixtures Nos. 1, 2, 3, and 4 on the brass and iron 

 parts of the spray pump. Several methods were tried in applying 

 the mixtures, the best results being obtained by using common 

 whitewash brushes provided with short handles. With these brushes 

 the vines of plats Nos. 1, 2, 4, and 5 were thoroughly washed with 

 the fungicide. The summer sprays were applied with a traction 

 sprayer. 



i Scott, W. M. Lime-sulphur mixtures for the summer spraying of orchards. Circular 27, Bureau of 

 Plant Industry, U. S. Dept. of Agriculture. 1909. 



[Cir. 105] 



