170 SIXTEENTH BIENNIAL REPORT 



tree, and is much better practice than to trim off so ruuch wood at the bottom. 

 Proper pruning, then tends toward better wood growth and greater fruitfulness. 



Cultivation. Tliis Operation first of all warms the soll in the spring so tliat 

 nitrifying l)acteria may start their work early and snpply the trees with that 

 eleruent which it needs most at the time ; namely, nitrogen. Cultivation sets free 

 plant food by breaking iip large soll particles into smaller ones and allowing 

 the smaller particles to become surrounded by film moisture. Tills moisture 

 acts as a solvent and carries the mineral elements needed for the growth of the 

 tree to parts above. 



Irrigation. Irrigation is absolutely necessary under arid conditions. The water 

 supply acts chiefly as a solvent and takes away that amount of food which is 

 immediately available to the upper parts of the tree. It is readily seen then that 

 Irrigation can not take the place of cultivation ; in fact, if cultivation is neglected, 

 the soil may become cold and soggy after Irrigation and spring growth be 

 actually retarded. 



Insect and Fungous Pests. It is well known that the presence of San Jose 

 Scale upon fruit trees will, in a short time, deplete their vigor to such an extent 

 that they are no longer fruitful. If the pest is left too long, the tree itself may 

 die. Apple tree anth'racnose, crown gall and numerous other troubles may 

 devitalize our trees. 



Cover Crops. These crops should be plowed under at the ordinary time of 

 plowing in the spring and before they deplete the moisture in the soil. Perhaps 

 their greatest function lies in keeping the soil well supplied with humus. Humus 

 adds directly to the water holding capacity of the soil, furuishes more air Spaces 

 in the soil and thus aids in warming it. With water and warmth, nitrifying 

 bacteria become active and nitrification takes place early in the season. It has 

 been frequently noticed by prune growers especially, that early plowing, on soils 

 that will permit it, eonibined with cover crops, favors the setting of large crops. 

 Again, certain kinds of cover crops, such as the legumes, afford us our cheapest 

 supply of nitrogen. Common vetch (A'icia satvia) contains 3.1 per cent of nitro- 

 gen in its dry matter. It may be stated here that a ton of vetch ordinarily 

 cured will contain about 1,500 pounds of dry matter or 45 pounds of nitrogen. 

 This is equal to an application of 300 pounds of nitrate of soda. 



Fertilizers. It is evident then that fertilizer is only one of the limiting factors 

 needed to produce good crops of fruit and is not a cure-all by any means. 

 In orchard management, a fertilizer is indicated only when other limiting factors 

 are brought up to par, and still the tree appears to lack vigor and refuses to 

 bear well and regularly. Because orchards seem to flourish year after year with- 

 out any fertilizers being applied or Avithout very much care, it is thought by some 

 that the orchard does not deplete the fertility of the soil. Such, however, is not 

 the case. The trees use up a great deal of plant food but get this by foraging 

 widely and deeply. Some observations by Dean I. P. Roberts, formerly of Cornell, 

 substantiate this point. He found that an orchard of mature trees between the 

 ages of 13 and 33 years used from the soil in making the roots, trunks, branches, 

 leaves and fruits, 1,336 pounds of nitrogen, 310 pounds phosphoric acid and 1,895 

 pounds of potash. That the fertility taken out of the soil by a wheat crop, both 

 grain and straw, in comparison for a period of twenty years. amounted to 425 

 pounds of nitrogen, 160 pounds of phosphoric acid and 110 pounds of potash. This 

 was estimated on a basis of a yield of 15 busheis to the acre of wheat and 7 

 pounds of straw to every three pounds of grain. 



Notwithstanding this heavy depletion of fertility by the orchards, we have 

 eastern state experiment stations including those of Geneva, Pennsylvania, New 

 Hampshire, New Jersey and others. that have been experimenting with fertilizers, 

 find they have found that fertilizing with potash and phosphoric acid very 

 seldom pays for the cost of handling the fertilizers, and sometimes there are 



