432 TUKEY 



Perhaps the outstanding contribution to general orchard-management 

 practices has been the use of mulches. While first found beneficial in apple 

 orchards, they have since proved of value for pears and to a limited degree 

 for peaches and cherries. Minor element deficiencies have tended to disappear 

 under mulch, potash and phosphorus have become more readily available, 

 and moisture supply has been increased. Associated with mulching are im- 

 proved soil structure, better aeration, and increased penetration of rain. 

 The mulching materials used are usually spoiled hay from a nearby farm, 

 bearing out the axiom that "it is an ill wind that blows nobody good." Mulch- 

 ing has proved "better than we know" and has been one of the major shifts 

 in orchard management in America. 



As the appraisal of nutrition becomes more refined and more exact, there 

 is considerable interest in foliar sprays. Such deficiencies as manganese, 

 magnesium, zinc, and boron have been corrected by foliage applications. 

 Further, it has been shown that bark applications may be effective under 

 certain conditions. Sprays of nitrogen, mostly in the form of urea, have proved 

 valuable supplements to soil applications. Urea is easily applied in the regular 

 spray program and may be absorbed in a few hours. It may be applied to 

 apple trees early in the spring in delayed dormant and pre-blossom sprays 

 when this element is needed to assist in fruit set. Additional sprays may be 

 made if the season so requires. Such a wait-and-see program tends to the 

 production of fruit of high color, since no excess of nitrogen is permitted as 

 maturity approaches. 



Not all plants respond equally well to sprays of urea. Apparently there is 

 a relation between toxicity to urea and response from it; that is, the peach, 

 potato, and cherry respond very little and will withstand concentrations of 

 10 to 20 pounds of urea to 100 gallons of water. The plum responds next in 

 order and will tolerate 8 to 10 pounds. The pear responds slightly less than 

 the apple and will withstand 6 to 10 pounds. For the apple, about 5 pounds 

 is correct. The grape and the cucumber respond readily and will tolerate only 

 3 to 4 pounds. 



An old bit of research, which still lays a heavy and controlling hand (some 

 might even say a dead hand) upon much horticultural thinking and practice, 

 is the so-called carbohydrate-nitrogen relationship. It is worth repeating 

 here because, though it may represent an oversimplification or only a partial 

 statement of the truth, it nevertheless is a good example of the synthesis of 

 research into a working hypothesis — more of which we today so badly need. 

 In American terminology we say "it works" and let it go at that. However, 

 this does give the opportunity at this point to stress that in our quest for 

 something new we in research have failed, too often, to put the pieces to- 

 gether into some framework of usefulness. The job is not done when the 

 experiment is completed. It is done when it is made intelligible to others 

 and can be used by them. This, then, is the excuse for introducing so elemen- 



