266 ELEMENTS OF AGRICULTURE 



plant lice or other sucking insects. There is no generally 

 used spray that combines the three purposes fungicide, 

 poison, and contact remedy for sucking insects. To be 

 successful in spraying, one must know what he is spraying 

 for, and apply the right spray at the right time. Apples 

 are commonly sprayed about three times, once just before 

 blossoming, once just after the petals fall, and once about 

 two weeks later. Bordeaux mixture and a poison are com- 

 bined. Potatoes are commonly sprayed about five times, 

 beginning when the plants are about six inches high and 

 repeating every one to two weeks, using Bordeaux and 

 poison. The particular treatment, of course varies in 

 different sections, because the weather and enemies differ. 

 For details in any section, one should apply to the State 

 Agricultural Experiment Station. 



QUESTIONS 



1. What are the worst ten weeds in the neighborhood? What is 

 the character that makes each one a bad weed, that is, able to live 

 in spite of man? How may each one be most easily controlled? 



2. What are the worst plant diseases in the region? How may each 

 of these be controlled? 



3. In how many ways do bacteria differ from the plants with which 

 you are most familiar? In how many ways do fungi differ from these 

 plants ? How do bacteria differ from fungi ? 



4. How do spores differ from seeds? 



5. In what ways may the spores of disease-producing fungi be 

 carried- to the plants which they infect ? 



6. Explain how spraying the leaves of the potato with Bordeaux 

 for late blight increases the yield of tubers. 



7. Explain why spraying pear and apple trees will not control 

 fire blight. Why is the removal and treatment of the hold-over cankers 

 the first step to be taken in controlling this disease? 



