EXPERIMENT STATION REPORTS. 155 



danger Avliatever of spotting the fruit and it will be found more effectual 

 and far less expensive than the ammonia solution of copper carbonate, 

 or the Burgundy mixture which was formerly used. 



The amount required for spraying an acre of grapes will depend upon 

 the age and strength of the vines as Avell as upon the date of the appli- 

 cation. For the average vineyard of bearing age, fifty gallons per acre 

 will suffice during the early part of the season but, while many restrict 

 themselves to the use of this quantity, it will be found better to increase 

 the quantity where the vines are large and the growth is thick and in all 

 cases sixty to eighty gallons can be used to advantage for spraying an 

 acre of grapes after the fruit has set. Arrangements should be made to 

 carry a high pressure and, when traction outfits are used, it should be 

 so gauged as to produce a fine spray even when the team is moving very 

 slowly. In this Avay only will it be possible to do thorough and effectual 

 work. 



Particularly if the growth is very thick, and the conditions are favor- 

 able for rot, it will often pay after the grapes are half grown, in addi- 

 tion to using the stationary nozzles, to have two men follow the rig with 

 "trailers," or lines of hose with one or more nozzles, at the ends of short 

 extension rods, with which they make sure that every grape is coated 

 with the spraying mixture. 



While no definite rule can be given for the number of applications 

 that should be made under all conditions, results show that at least tAVO 

 applications will be well repaid from the benefit that will result against 

 the grape mildews, even though no rot appears and, in seasons when the 

 latter disease is troublesome, from five to seven sprayings can be given 

 with profit. At the very least, one treatment should be given before the 

 blossoms have opened and a second when the fruit is of the size of small 

 peas. In vinej^ards where the rot has been troublesome the previous 

 year the number of applications should certainly be increased. The first 

 spraying then should be given when the new growth is twelve to fifteen 

 inches long and another just before the blossoms open. The use of a 

 treatment with copper sulphate solution (two pounds in fifty gallons of 

 water) in the earh^ spring, also seems to be very helpful in vineyards 

 where rot has prevailed. 



After the fruit has set, the spraying should be continued if the Aveather 

 seems favorable for it, or if it is proving injurious in unsprayed vine- 

 yards. The treatment is necessarily preventive in its nature and spraying- 

 will be of no value to a grape after it has been attacked, hence the only 

 safe way is to make sure that the fruit and leaves are kept coated. The 

 disease is spread by means of spores which develop only in minute drops 

 of water and, as it generally takes tweh^e to fourteen days from the time 

 one crop of spores has developed until the next appears, it will suffice 

 if the vineyard is sprayed within ten days after a rain or period of muggy 

 weather. Ordinarily then from two to four applications after the fruit 

 has set will be sufficient although,, if rains are frequent and wet, warm 

 A\'eather continues into August, one or two other treatments, using the 

 Induced formula with the minimum amount of lime Avill be of value. 



Depending upon the convenience with Avhich Avater and the other spray- 

 ing materials can be obtained and the difficulties that may be met with 

 in preparing the mixture and making the application, from five to ten 

 acres may be s|)rayed in a day and the work done A^ery thoroughly. The 



