1016] HORTICULTURE. 541 



fact that the nitrogen sprayed on the trees was dissolved and reached the 

 roots, whereas the nitrates spread on the ground were added in May when 

 the ground was dry, hence did not dissolve and reach the roots. In order 

 to secure benefit from the nitrates tliey should be applied during the early 

 l)art of March when the ground is sufficiently moist to dissolve them and also 

 before the trees come into bloom. Nitrogen applied at this time has been found 

 to cause a larger percentage of set of fruit in April, an important change in the 

 character of the foliage, and a stimulation of the wood growth. 



The experiments indicate that the stimulating effect of nitrate of soda is 

 more lasting in its effects than formerly believed and that its benefits will 

 extend over into the second season and perhaps longer. The best method 

 of applying nitrate of soda to orchards is to spread the dry crystals broadcast 

 on the ground under the trees and harrowing soon after applying. Six lbs. 

 of nitrate of soda, equal to about 1 lb. of actual nitrogen, applied to a mature 

 bearing tree is believed to be ample to restore seriously weakened trees to a 

 normal condition. This amount should be reduced one-half the second year, the 

 station's experiments showing that a full pound of nitrogen applied the second 

 year produced too much wood growth and too much fruit that was undercolored 

 and oversized. The cost of furnishing the required nitrogen at the rate recom- 

 mended was $15 an acre. 



The above amounts of fertilizer are recommended for use only on trees 

 which are in a somewhat run down condition as indicated by thin foliage, 

 weak wood growth, small fruit, and the presence of certain physiological 

 troubles, such as "fruit pit," little leaf, die-back, etc. 



Further experiments are to be conducted to confirm these conclusions as a 

 whole. 



The authors point out that nitrate of soda does not exert much influence 

 on the soil, and therefore in order to improve the physical condition of the soil 

 in many orchards it is necessary to add organic matter. During the last two 

 years those orchards which have used clover and alfalfa in the presence of 

 sufficient moisture have shown a strong improvement. The use of these legu- 

 minous crops should be dispensed with for a while and systematic clean culture 

 practiced when signs of over stimulation appear. 



Condition of root system, of apple trees in the Hood River district, R. W. 

 Allen {Oregon Sta., Rpt. Hood River Sta., 1915, pp. 20-24, figs. 2).— The results 

 are given of a preliminary investigation started in 1913 to determine in a 

 general way the condition of the root system of apple trees in orchards varying 

 in age and under different cultural treatment. 



In the orchards examined many of the fibrous roots of the trees were dead, 

 this condition being worse in old orchards kept under clean cultivation and 

 without irrigation. Sod culture without irrigation was very similar in result 

 to that of continuous clean culture, but the conditions, as a whole, were worse 

 where shallow implements of tillage had been used. Sod culture in which 

 clover had been grown with irrigation showed the soil and roots of trees to 

 be in very good condition. 



"Fruit pit" was found to be worse under the worst conditions of the soil 

 and upon trees having root systems in the most critical condition. In less 

 serious conditions of soil the roots of "pit" trees were either normal in vigor 

 or nearly so. Winter injury appeared to be most prevalent on soils of poor con- 

 dition, but no relation was found to exist between the seriousness of the trouble 

 and the condition of the roots of the trees. The investigation as a whole 

 strongly indicates that the weak and yellow condition of the trees, much of 

 63270°— No. 6—16 1 



