DIPPING AND FUMIGATION OF NURSERY STOCK 



13 



San Jose scale: Apple, 58 trees; peach, 58, and plum, 5. These trees had 

 just been dug from the nursery row. They showed weakness from the 

 effects of the scale, but were otherwise in excellent condition. A part of 

 these trees were treated with hydrocyanic-acid gas on April 10, 1917. 



In the spring of 1918 a small nursery was started on the experimental 

 grounds at Columbia for the purpose of obtaining trees to continue scale 

 control investigations. Both peaches and apples were grown and in the 

 summer of 1919 scale infested trees were placed with them and by fall the 

 stock was all heavily infested. In March 1920 these trees were used in 

 fumigating and dipping experiments. 



As has already been explained, one fluid ounce 66 Baume sulphuric 

 acid, 1 ounce potassium cyanide and three fluid ounces of water for 100 cubic 



Fumigating Box used at the Missouri Agricultural Experiment Station. Notice the cleats 

 against which the lid fits. These cleats are covered with felt to prevent the escape of gas. 



feet is most commonly used in fumigating nursery stock. Some of the 

 nurserymen of Missouri had complained of severe burning of the stock 

 when used this strong so two strengths of hydrocyanic-acid gas were used 

 in the work in 1916. The regular 1-1-3 formula was tried and a formula 

 just half as strong (%-%-!%) was also tried. 



A fumigating box was constructed from 1 inch cypress lumber. The 

 box was made 7 feet long, 3 feet wide and 2 feet deep, havirtg a total 

 capacity of 42 cubic feet. The top of the box was hinged on so as to form 



