34 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 177 



SUMMARY 



1. Hydrocyanic-acid gas did not in every case completely control the 

 San Jose scale. However, the gas used at a strength of 1-1-3 gave better 

 results than the weaker strength of %-%-!%. The 1-1-3 strength gave as 

 good results as the 2-2-6 strength. Sodium cyanide used at the strength of 

 1-1M.-3 killed 100 per cent of the scale. 



2. Hydrocyanic-acid gas was more effective when used upon dry 

 plants than upon wet. A larger percentage of the scale was killed. 



3. All strengths of the hydrocyanic-acid gas caused more or less 

 Injury to the plants. The stronger it was used, the more injury it caused. 



4. The 1-1-3 formula should always be used in fumigating nursery 

 stock, and the stock should be dry. There may be greater danger of in- 

 jury to the plants, but the scale will be more completely controlled, and 

 this is the most important factor. 



5. Carbon bisulphide did not control the scale and it caused a very 

 high percentage of injury. Its use as a fumigating material for the control 

 of San Jose scale on nursery stock should 'be discouraged. 



6. Lime-sulphur used at 1-9 and 1-7 strengths gave fairly good results 

 in controlling the scale. The 1-9 solution gave perfect results on pears and 

 plums. 



7. The sulphur dips injured the plants to some extent. The plants 

 dipped both tops and roots showed more injury than those dipped tops 

 only. 



8. The miscible oil gave the best results, 100 per cent of the scale 

 being controlled in every case but one and in this case the control exceeded 

 99 per cent. 



9. Miscible oil caused some injury to the plants. Those dipped tops 

 and roots were injured most. When treating nursery stock with miscible 

 oil the roots should not be dipped. 



10. Lemon oil or nicotine sulphate should not be used as dips for con- 

 trolling scale on nursery stock. 



11. None of the materials used completely controlled the San Jose 

 scale. 



12. All scale-infested nursery stock should be burned or destroyed in 



some other way. 







13. Nursery stock which has been subjected to infestation, but is not 

 infested should be treated before being placed on the market. 



14. The best results should be expected by treating the stock with 

 hydrocyanic-acid gas 1-1-3, or with miscible oil at the strength of 1-12 or 

 1-15, tops only. 



