12 GEAPE-SPRAYING EXPERIMENTS IN MICHIGAN IN 1909. 



vineyard from the other plats sprayed with this fungicide and can 

 hardly be compared with them, as the disease seemed to be more 

 easily controlled here. They were not far from the check, however, 

 and there is no ajjparent reason to doubt that but for the spraying the 

 grapes would have been as badly damaged as on plat G. In the three 

 plats, No. 14, sprayed five times with 4-3-50 Bordeaux mixture, 2 

 pounds of resin-fishoil soap being added the last time, was in the best 

 condition. Xo. 12, sprayed seven times, and No. 13, sprayed five 

 times with the same mixture without the soap, suffered somewhat 

 more damage from the rot. 



These results would indicate that it may not be necessary to spray 

 more than five times when soap is added at the last spraying to make 

 the mixture spread out and adhere more closely to the berries. More 

 work is necessary to determine this point, however. With the other 

 spray mixtures the results were not equal to those with the Bordeaux 

 mixture, as may be seen in Plates I and III. 



Of the two nonstaining compounds used throughout the season for 

 comparison, the neutral copper acetate seemed to be the most effective 

 fungicide. It, however, injured the vines considerably, in some 

 cases almost entirely defoliating them; consequently the fruit was 

 small and stunted, as shown in Plate III. figure 2, and did not ripen 

 well. It was sold as a poor grade of wine grape. Used as a non- 

 staining compound in the last spraying, the neutral copper acetate 

 seemed to have no ill effects. In the plat sprayed with ammoniacal 

 copper carbonate there was no injury to the foliage, but the damage 

 from rot was very great, as shown in Plate III, figure 1. Only a few 

 20-pouncl baskets of wine grapes could be picked from this plat. 



The lime-sulphur mixtures can hardly be considered good fungicides 

 for use on grapes. In the case of the self-boiled lime-sulphur there 

 was little injury to the foliage but a high percentage of rot, as may be 

 seen in Plate III, figure 3, and what few grapes survived were sold in 

 bulk. In the case of the commercial lime-sulphur the rot was not 

 controlled as w^ell as by the Bordeaux mixture and the vines were 

 badlj^ damaged. The growth of foliage was much less than in the 

 other plats, the leaves were small and browned, the shoots were short, 

 and the bunches of fruit were much undersized, ragged, and poorly 

 ripened. (See PI. Ill, fig. 4.) Twenty 8-pound baskets were all the 

 marketable grapes harvested from the Y>\at, the rest being sold in 

 bulk. The crop was not only badly injured for that season, but the 

 canes for the next season's crop were small and in poor condition. 

 Grape foliage seems to be extremely susceptible to injury from this 

 fungicide. 



A comparison of the grapes of the check with those of plat 14, as 

 shown in Plate I, figure 2, and Plate II, figures 1 and 2, gives us 

 a sharp contrast. In the check we have a loss of 90.7 per cent, as 



[Cir. 05] 



