PLANTING AND CARE OF THE ORCHARD. 43 



although the risk of permanent injury from this source is much 

 less than is generally supposed. 



g — Mulching sometimes causes great danger by fire. 



h — The mulch about plants may harbor insects, such as cur- 

 culio, etc., which might injure the trees. These are most easily 

 kept in check by clean cultivation; but where fruit trees are 

 mulched, pasturing hogs in the orchard will greatly help in check- 

 ing the spread of such insects as remain in the fruit after it 

 falls. 



Cover crops is a term used in connection with the growing 

 of crops in orchards. In a general way, the best fruit growers 

 are a unit in believing in the importance of clean cultivation for 

 orchards. However, as we have already noted, this is often 

 impractical on steep hillsides liable to wash badly. Clean cul- 

 tivation also leads finally to a poor condition of the soil which 

 can only be fully remedied by the addition of humus. This humus 

 may be added by the application of coarse stable litter or other 

 organic matter directly to the land. In this case the humus is 

 confined almost entirely to the few upper inches and is not dis- 

 tributed throughout the soil as it is by the growth of clover or 

 similar crops. The decaying roots of a cover crop leave humus 

 both in the sub-soil and in the surface soil, thus rendering the 

 whole mass more porous. 



Still other advantages of cover crops are (a) they protect the 

 soil to some extent from deep and sudden freezing and thawing; 



(b) they prevent the snow from blowing away in the winter; 



(c) such cover crops as clover and peas not only improve the 

 physical conditions of soils on which they grow, but actually 

 leave them richer in nitrogen. On this account plants of this 

 class are especially desirable for orchards, (d) They are some- 

 times helpful in checking the production of the wood in late sum- 

 mer by using up some of the plant food and moisture in the soil. 

 This checking of late growth in the fall ripens up the wood 

 earlier, leaving the tree in better shape to stand the winter. 



How to combine the advantages of cover crops and cultiva- 

 tion is often an important question for orchardists. In many 

 fruit sections, this may be done by the cultivation of the soil 

 during the summer and seeding down to some cover crop in the 



