6 EXPERIMENTS IN THE CONTROL OF GRAPE ANTHRACNOSE. 



In the spring of 1910 after the fungicide had been applied to plats 

 Nos. 1, 2, 4, and 5, a series of late frosts killed back the young growth 

 three different times. As this practically eliminated all possibility 

 of fruit for the season, the experiments were discontinued for the 

 year. The experiments were continued in 1911, as had been planned. 

 Plats Nos. 1, 2, 4, and 5 were treated while the vines were dormant, 

 as in 1910, except that a 4 per cent instead of a 10 per cent solution 

 of sulphuric acid was used on plat No. 4. The stronger solution 

 seemed to injure some of the buds. Plats Nos. 7, 8, and 9 were 

 thoroughly sprayed four times — once before the blossom, a second 

 application immediately after the blossom, and the other two appli- 

 cations at intervals of two weeks. 



The treatment of the dormant vines on plats Nos. 1, 2, 4, and 5 

 was continued in 1912 as in 1911. Plats Nos. 6, 7, 8, and 9, how- 

 ever, all received the same treatment in 1912. They were sprayed 

 five times with 4-3-50 Bordeaux mixture— once before the blossom, 

 once immediately after the blossom, and the other applications at 

 intervals of about two weeks. Two pounds of rosin-fishoil soap 

 were added to each 50 gallons of Bordeaux mixture in the last two 



applications. 



RESULTS. 



As there was no fruit in 1910 it was, of course, impossible to obtain ac- 

 curate data as to the effect of the various treatments. There seemed 

 to be less diseased wood in the plats which were treated than in the 

 others. In 1911, counts were made of the sound and diseased 

 berries on 1,000 average bunches of grapes from each control plat, 

 with the results shown in Table I. Much of the young wood in the 

 control plats was injured by the disease. A portion of a vine from 

 one of the control plats is shown in Plate II, figure 2, while a por- 

 tion of a vine showing the average condition in the treated plats is 

 reproduced in Plate II, figure 1 . There was practically no damage 

 from disease in plats Nos. 1, 2, 4, and 5, which were treated before 

 the buds swelled, while in the plats which received only the summer 

 spray there were a few diseased berries and some diseased wood. 



The results in 1912 were much the same as in 1911. The amount 

 of diseased fruit on plat No. 3, the control, was not as great as in 

 1911, according to counts made of the sound and diseased berries 

 on 1,000 average bunches of grapes, owing probably to weather 

 conditions and the pruning out of the diseased wood the previous 

 seasons. Considerable diseased wood was present in the control, 

 as in the season of 1911, and the foliage was somewhat damaged. 

 There was practically no evidence of disease in plats Nos. 1, 2, 4, 

 and 5, which were treated while the vines were dormant. In the 

 plats receiving only the summer treatment with Bordeaux mixture 



[Cir. 105] 



