18 



5. Why do fruit trees often stand still, making no sign of growth 

 for a Icng time after they liave been planted ? 



6. How long do root-hairs persist ? Do they die every year, every 

 second year, or do they last indefinitely ? Prove your answer. 



7. Why are forest trees commonly shallow rooted ? 



8. What influence might constant mulching have on the roots of 

 fruit trees ? 



9. Why do fruit trees injured by borer or whiffletree often bear 

 fruit earlier than sound trees ? 



10. How does ringing affect the part above the ring ? 



11. How does an injury to the stem of a tree affect the food 

 supply of the crown ? 



12. Does the trunk of a tree grow longer or shorter after the 

 head forms? 



13. How does an injury to the leaves affect the food supply ? 



372 



1 



