Tukey • Horticulture is a Great Green Carpet that Covers the Earth 1 59 



distress has been experienced in south- the case no longer rests with chemical 

 ern sections in some seasons with analysis of the soil alone. Analyses of 

 delayed and scattered foliation and the tissues of the plant have been found 

 blossoming and attendant financial re- valuable to supply additional informa- 

 verses. The answer has been found in tion. The use of nitrogen has become 

 varying hours of chilling required by fairly well standardized with either fall 

 different varieties of peaches, so that applications orearly spring applications, 

 varieties which are adapted to the long But, as dependence has been placed 

 chilling provided by nothem winters do largely upon nitrogen, other materials 

 not break dormancy in southern regions, have been found of increasing impor- 

 Varieties of tree fruits for the South tance, such as phosphorus and potas- 

 are now catalogued as to the amount of sium. Various other deficiency troubles 

 chilling required to break dormancy. also have been identified, and have 

 The bulbing of onions, the tubering been corrected by the application of 

 of potatoes, the bolting of celery and specific materials, as the littlc-lcaf dis- 

 lettuce, and the adaptation of certain ease of citrus with zinc, and the inter- 

 floricultural crops and woody oma- nal corking of apples with boron, 

 mentals to various geographical loca- Perhaps the outstanding contribu- 

 tions are now better understood and tion to general orchard management 

 predictable. practices has been the use of mulches. 

 Another recent contribution to or- While first found beneficial in apple 

 charding has come from studies involv- orchards, they have since proved of 

 ing the growing of fruit tree rootstocks value for pears and to a limited degree 

 at controlled root temperatures. Until for peaches and cherries. Minor ele- 

 recently, there has been great difficulty ment deficiencies have tended to dis- 

 in determining the natural adaptation appear under mulch, potash and phos- 

 of several of the clonal Mailing apple phorus have become more readily 

 rootstocks. Now it is found that certain available, and moisture supply has been 

 of these rootstocks, such as Mailing increased. Associated with mulching 

 IX produce new roots even at root are improved soil structure, better 

 temperatures of 44° F., whereas they aeration, and increased penetration of 

 disintegrate in soil temperatures of 77° rain. 



F. and higher. On the other hand. As the appraisal of nutrition be- 



French Crab seedling rootstocks pro- comes more refined and more exact, 



duee no new roots at 44° F., but grow there is considerable interest in foliar 



luxuriously at 77° or higher; and Mall- sprays. Such deficiencies as manganese, 



ing VII seems adapted to a wide range magnesium, zinc, and boron have been 



of soil temperature, producing roots at corrected by foliage applications. Fur- 



55° F. as well as at 77° F. The results ther, it has been shown that bark ap- 



explain the growing popularity of Mall- plications may be effective under cer- 



ing IX in the North and of Mailing tain conditions. 



VII as a widely adapted apple root- Propagation and weed control.— 



stock in the United States, and the The propagation of horticultural plants 



abandonment of Mailing IX in south- by vegetative means has been greatly 



em regions in place of French Crab improved by research. Studies have 



rootstocks which will tolerate high soil shown the differences which exist in 



temperatures. plant parts used as cuttings which are 



Nutrition and fertilizers.— As re- taken from plants of var\ing age and 



gards fertilizers and fruit tree nutrition, composition. Plants in the so-called 



