SODIUM CYANID FOE FUMIGATION PURPOSES. 89 



cyanid. This revision is accomplished by using a high-grade sodium 

 cyanid with dosages one-fourth less than the amounts scheduled 

 for the potassium salt. Thus if a dosage recommended should read 

 that it requires 12 ounces of potassium cyanid to secure certain 

 results against a particular insect the same results could be accom- 

 plished with 9 ounces of a high-grade sodium product. In general 

 fumigation against the purple scale {Lepidosaphes heckii Newm.) 

 the writer has recommended a full schedule No. 1 of potassium 

 cyanid. 1 Should one desire to produce the same results against this 

 insect with sodium cyanid, he would use a schedule one-fourth less, or 

 dosage equal to three-fourths of the dosage amounts given in schedule 

 No. 1 of potassium. Such a three-fourths schedule with high-grade 

 sodium cyanid will produce practically the same amount of gas as the 

 full schedule No. 1 of potassium. 



Plate IX gives such a schedule, which is called schedule A for 

 sodium cyanid. 1 By using this schedule with a 124 to 130 per cent 

 cyanid of sodium practically the same results will be secured as with 

 full schedule No. 1, as given in Part I of this bulletin, with potassium 

 cyanid. 



These dosages are in ounces and are based on a knowledge of two 

 measurements of the tree — the distance around the bottom and the 

 longest distance over the top. Having secured these two distances 

 for any tree, the dosage for that tree may be found in that part of the 

 table where the lines for these measurements intersect. 



DOSAGES RECOMMENDED FOR SCALE PESTS. 



Purple scale. — In general fumigation for the purple scale (Lepido- 

 saphes heckii Newm.) use full schedule A of sodium cyanid (Plate IX). 

 With its use all insects and more than 99 per cent of the eggs are 

 destroyed on the leaves and branches. Exposure should last 1 hour. 



Bed scale. — For the red scale (CJirysompJialus aurantii Mask.) 

 use a three-fourths schedule (three-fourths of schedule A of sodium 

 cyanid [Plate X]). An exposure of 45 minutes is sufficient. 



Yellow scale. — For general work against the yellow scale (CJiry- 

 somphalus citrinus Coq.) three-fourths of schedule A of sodium 

 cyanid (Plate X) will prove satisfactory. The section in which the 

 yellow scale is most serious is about Redlands, San Bernardino County, 

 where a great acreage is planted on terraced land. Owing to the 

 irregular topography of terraced orchards the tents seldom he as 

 closely to the ground as on level land, and as a consequence there 

 usually is a greater amount of leakage. For terrace fumigation 

 full schedule A (Plate IX) should be used. Exposure should be 45 

 minutes. 



1 For detailed use of such schedule, as well as methods of measuring trees, see pp. 34-37, Part I, of this 

 Bulletin. 



