- 9 



determine the pressure while running the sprayer with all nozzles 

 open. Then, with the help of tables supplied either by the Exten- 

 sion Service or the sprayer dealer, choose the nozzles required 

 for the output of 17.6 gallons per minute (8.8 gallons from each 

 side). About 85% of the total spray output should be from the top 

 two-thirds of the air outlet. Usually, this means that one small 

 nozzle is placed in the lower third of the air outlet, the top 

 nozzle outlet is closed, and the remainder of the nozzles are spaced 

 in the upper two-thirds of the air outlet with the larger nozzles 

 at the top . 



For 6X sprays to be applied at 2 mph , choose the nozzles re- 

 quired for a total sprayer output of 8.8 gallons per minute. We 

 try to use at least 6 or 7 nozzles on each side of the sprayer in 

 order to obtain good distribution of the spray in the air stream. 



Timing of the sprays is very important. My work with alternate 

 row spraying has been based on 7-day intervals between sprays (row 

 middles 1 and 3 one week, 2 and 4 the next week)but I would vary 

 this by one or two days under special conditions. We have applied 

 the spray under any conditions except heavy rain or wind above 8 mph 

 In hot, dry summer weather, we have done most of the spraying be- 

 fore 9 A.M. It is hard to get good spray deposit on a v&ry hot, 

 dry day. 



In most of the work with 6X sprays, we have mixed the chemi- 

 cals at 4X. This means 4 times the standard recommended amount of 

 each chemical. For example, the Pennsylvania spray program call'^ 

 for Captan SOW to be used at the rate of 2 lbs. per 100 gallons of 

 dilute spray early in the season. Mixing this chemical at 4X means 

 that it is mixed at 8 Ibs./lOO gal. early in the season and at b 

 later in the season (1.5 lbs. dilute). 



While mixing the chemicals at 4X has been successful in our 

 trials with an exception to be noted later, it should be clearly 

 understood that the amount of chemical used should be adjusted to 

 conditions. It vould be foolish to use a very low amount of miti- 

 cide or fungicide under conditions where maximum effectiveness vias 

 needed . 



In trying to obtain low cost pest control by using large air- 

 blast sprayers to apply moderate amounts of chemical from alternate 

 row middles, we control the type of eouipment used, the amount of 

 spray applied, the interval between sprays, and the kind and arount 

 of chemical. Such a program, properly supervised, has been suc- 

 cessful at 50 to 65 per cent of the cost of the present Pennsylvania 

 dilute spray program for apples. The principal dangers are (i) that 

 growers will attempt to cut chemical usage without the necessary 

 control of equipment and application method, (ii) that less than 

 about 30 gallons of spray per acre may not give control of powdery 

 mildew and (iii) that oil sprays of less than 100 gallons of snray 



