THE MONTHLY BULLETIN. 251 



RESULTS OF COMBINATIONS. 



Experiment No. 1. Ninety-five to 98 per cent of all vine hopper 

 mTiiphs present at time of spraying were killed. Close examination 

 eight to ten days after spraying showed that practically all hoppers 

 hatching since the spray was applied had been killed. The control of 

 mildew was complete and satisfactory, as no injury was caused by 

 mildew on this plat throughout the season. 



Experiment No. 2. Seventy to 75 per cent of vine hopper nymphs 

 present at time of spraying and practically all those hatching during the 

 next ten days were killed. Many of the larger forms which were prac- 

 tically full grown were not killed. ]\Iildew control was complete and 

 as satisfactory as in Experiment No. 1. 



Experiment No. 3. Results were about the same as on plat No. 2, 

 except that a few moi^e vine hoppers were killed. Results on Experi- 

 ments 2 and 3 show that 40 per cent nicotine at rate of 1 pint to 200 

 gallons of spray Js necessary when the nymphs are more than half grown. 



Experiment No. 4. The fish glue wa.s added to give greater spreading 

 and to ascertain if the results would warrant the extra trouble and 

 expense. It is difficult to make the ordinary spray solution spread over 

 the under surface of Emperor leaves. The results were entirely satisfac- 

 tory in that mildew was completely controlled and at least 99 per cent 

 of all vine hoppers present at time of spraying and most of those hatch- 

 ing during the next ten days were killed. ]\[ildew control was com- 

 plete and satisfactory, and no further treatment was required through- 

 out the season. 



At harvest time the results on plat 4 as contrasted with the rest of the 

 Emperor vines sprayed with soap and nicotine for control of hoppers 

 and dusted three times with dry sulphur for mildew control, were 

 very noticeable in that the vines sprayed one time with Atomic sulphur 

 and nicotine produced more grapes to the biuich all of which were more 

 uniform in size, free from mildew and brought from 15 to 35 cents per 

 crate more because of the absence of mildew and the uniform size and 

 better appearance of all grapes in the cluster. The cost of the treatment 

 with Atomic sulphur and Black leaf "40" was less than $5.00 per acre, 

 and the vines yielded a net return of from $25.00 to $35.00 per acre 

 more than was obtained from the rest of the vineyard where whale oil 

 soap and nicotine were used alone for hopper control and where three 

 applications of dry sulphur were applied for mildew control. There 

 were many small grapes, and mildew was present among the fruit 

 clusters by harvest time. 



As it happened, no mildew appeared in this particular vineyard 

 before blooming time, consequently no injury had been caused before the 

 spray was applied. Where mildew does not develop before this time, 

 the one application will be effective for both mildew and vine hopper 

 control during normal seasons under California conditions. In vine- 

 yards where mildew develops and causes injury earlier in the season, the 

 vines should be sprayed once before blooming to control mildew. 



A great deal of work was done by Mr. Roberts and Mr. Roullard in 

 the use of different kinds of soap alone and in combination with nicotine 

 for hopper control, and the writer takes the liberty of reporting briefly 

 herewith. One gallon of liciuid whale oil soap and one pint Black leaf 



5— 171.J4 



