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Our original dust formulations were made on the basis of applying 35-40 

 pounds of dust per acre prepared by the trial and error method based on per acre 

 dosage rates of the materials when applied in spray form at about 400 gallons per 

 acre dilute. Other dusts such as 5% DDT were simply taken from the shelf and, of 

 course, do not figure out to be more than the aniount of DDT applied in a 200 gallon 

 per acre treatment. 



All dust mixture formulations are always given in terms of per cent actual 

 active ingredient content. For example, a 37o Phygon dust contains 6% of Phygon 

 XL which contains 50% active ingredient. The average per acre application rate 

 last season had dropped to 30 pounds and most of our formulations are now based 

 on 33 pounds per acre which very much simplifies the calculations involved, 

 Vermont talc has been the most commonly used inert dilutent. 



Two basic fungicide dusts are used for primary scab control: 37. Phygon 

 and 57, captan. Other fungicide dusts would include 47. Niacide M, ferbam and 

 elemental sulfurs or combinations of almost any of the above. A 27. Phygon dust 

 will be used this year by some growers. Phygon is seldom used beyond petal fall 

 for scab control and ferbam may be combined with Phygon or captan for rust control. 

 The elemental sulfurs are not used for primary scab control. The elemental sulfurs 

 will be added to Phygon or captan dusts by some growers this year for mildew con- 

 trol. The application of sulfur-containing dusts this next season presents a ■ 

 fire explosion threat which must be taken into account by the airplane operators. 



The two basic insecticide dust formulations are 57. DDT and 1%7, Parathion. 

 4% Halation dusts are also used for aphid control. Mixtures of any of the 

 foregoing in addition to dusts containing 157o aresenate of lead, 5% Methoxychlor, 

 47o Kelthane, 27. Thylate, 2%7o Mercury and Aramite have been used. Due to recent 

 tolerance restrictions this material cannot be used under our conditions, 



— C, Lyman Calahan 



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