EXERCISES 265 



wounds larger than an inch and a half in diameter from 

 decay, it is well to paint them. Raw linseed oil and pure 

 white lead mixed to a thick paste make the best paint for 

 this purpose. 



In pruning large limbs in which there is danger of the 

 weight of the branch stripping the bark before the limb is 

 entirely sawed off, a cut is made on the under side of the 

 branch about a foot from the trunk, by sawing about a 

 third through the branch. The branch is then sawed off 

 from the upper side a short distance beyond this point. 

 The stub is then pruned away close to the trunk without 

 danger. The cleaner the cut, the more quickly it will heal, 

 hence in pruning large branches, it is advisable to trim 

 the cambium layer with a sharp knife after the branch is 

 sawed off. Tools that make sharp, clean cuts rather than 

 jagged wounds should always be used in pruning. 



EXERCISES 



1. Name the two mulching systems and give the advantages 

 of each. 



2. Is the practice of cover-cropping common in your locality? 

 What kinds of cover crops, if any, are used? 



3. Obtain roots of vetch, mammoth clover, peas, and beans, 

 and observe the nodules in which live the bacteria that have 

 the power of taking nitrogen from the air and giving it to the 

 nodule-bearing plants. 



4. How much seed would it take to sow a cover crop of winter 

 vetch in an orchard 384 feet long and 256 feet wide? When 

 should it be seeded and when should it be plowed under ? 



5. How are orchards usually fertilized in your section? 

 Are commercial fertilizers used ? 



6. What is the effect of nitrogen on plant growth? How 

 do potash and phosphoric acid affect fruit production ? 



