Methods of Control 



387 



Table 21 is used per 1,000 cubic feet of space, and if 

 the greenhouse to be fumigated contains 15,000 cubic 

 feet, then multiply the number of cubic feet con- 

 tained in the greenhouse by the amount of cyanid 

 to be used per 1,000 cubic feet, 1,500 times J/^ 

 equals 7.5 ounces cyanid. If there is the least doubt 

 as to the amount of gas the plant can stand without 

 injury the initial dose should not exceed one-fourth 

 ounce for each 1,000 cubic feet of house space. 



Table 20 



Amounts of Cyanid and Number of Fumigations 



Sufficient to Destroy Various Greenhouse Pests 



Insects 



•ApHids 



Azalea lacewing 



Thrips 



Greenhouse white fly ... . 



Long scale 



••Greenhouse orthezia. . , 



**Palm mealybug 



Palm aphis 



**Long-tailed mealybug . , 



Florida red scale 



Thread scale 



Aspidistra scale 



Soft brown scale 



Hemispherical scale 



Tessellated scale 



Florida fern caterpillar. . . 

 tCitrus mealybug 



Ounces per 



1,000 Cubic 



Feet 



H 



'^ 

 2yi 



2^ 

 2^ 

 2^ 

 2^ 



5 

 5 



Number of 



Fumigations 



Required 



I 



I 

 3 



3 



I 

 2 

 I 



I 

 3 

 3 

 3 



3 

 3 

 3 

 3 

 I 

 3 



Intervall 

 Between 



Days 



10 

 7 to 9 



31 to 38 



do, 

 do. 

 do, 

 do, 

 do. 

 do. 

 do, 



do. 



•For the most part aphids can be controlled with one-half ounce 

 of sodium cyanid per I, coo cubic feet, although there are a few 

 species which are quite resistant to this gas and not so readily killed. 



tThe greenhouse Orthezia and mealybugs around the roots of 

 plants are very difficult to kill, and this dosage is recommended only 

 for those occurring above the soil. 



