APPLE POWDERY MILDEW. 27 



does not color properly. Ammoniacal copper carbonate is practically 

 as effective as Bordeaux mixture against this disease and leaves no 

 deposit on the fruit to hinder coloring; it is therefore preferable to 

 Bordeaux mixture for such use. 



(7) The results of mildew control are cumulative, and with the 

 establishment of adequate control the crops of fruit are substantially 

 increased. 



(8) These experiments have shown that the disease can be effec- 

 tively controlled by spraying in accordance with the following 

 schedule, which is recommended: 



First application. Spray with lime-sulphur solution diluted 1 to 50 when 

 the cluster buds have separated, but before the blossoms open — the " pink " 

 spray. 



Second application. Spray with the same material in combination with 

 lead arsenate for codling-moth control as soon as the petals fall and before 

 the calyx is closed. 



Third application. Spray witli ammoniacal copper cdrbonate in combina- 

 tion with lead arsenate for codling-moth control about three or four weeks 

 after the second application. 



If subsequent applications are necessary they should be made at 

 intervals not greater than four weeks, using ammoniacal copper car- 

 bonate as a fungicide. 



In spraying it is important to cover every part of the leaves and 

 twigs, and special attention should be given to the terminals. A 

 pressure of 200 to 250 pounds should be maintained, or sufficient to 

 drive the spray in a fine mist through the tops of the trees. High 

 pressure is especially important if spray materials are used which 

 have poor spreading qualities. Eddy-chamber nozzles of the " driv- 

 ing-mist" type should be used. 



(9) In the production of sulphur spotting of the fruit, high tem- 

 perature from burning sunshine is the determining factor. It is 

 believed that the injury is not the result of toxic chemical action of 

 sulphicls in solution at the time of spraying, but it probably is due 

 to the heating of the spray deposits to such a degree that death of the 

 adjacent cells occurs, the results being partly due to the physical 

 effects of the heat and partly to the chemical effects of volatilized 

 sulphur compounds. 



