Oct. 1, 1921 Influence of Period of Transplanting 43 



formation of an abundant lateral root requires a favorable water content 

 in the soil and a sufficiently high soil temperature. Although summer 

 soils are warm, yet, in spite of occasional irrigation, the greatest loss of 

 transplants from drought at Savenac Nursery occurs during July and 

 August, indicating that there is less available soil moisture during that 

 period, or at least that there is a smaller balance for growth when the 

 transpiration loss of the plant has been met. 



It seems, therefore, that in the foregoing series the plant organism 

 was most deeply disturbed by being transplanted in midsummer. This 

 appeared to be a consequence of the high evaporation and lack of moisture 

 in the soil, along with the greater topheaviness of the plant. The May 

 20 transplants gave evidence of having been most severely set back, a 

 result which must be attributed either to external conditions or to the 

 internal state of the plant. The Savenac Nursery weather records show 

 a precipitation of 2.16 inches in April, 1914, well distributed throughout 

 the month, with only seven clear days. In May, previous to the 

 twentieth, there fell 0.58 inch of rain, and 12 out of 19 days were cloudy 

 or partly cloudy. On May 20, the soil was well stored with water and 

 was favorable for the reception of plants. The maximum temperature 

 on that day was 72° F., and it and the eight days following were partly 

 cloudy. During the period from May 22 to 28, inclusive, 0.46 inch of 

 rain fell, every day yielding at least a trace. The weather and soil 

 conditions were, therefore, sufficiently favorable to convince the writer 

 that the reason for the marked checking of the growth of the May 20 

 lot lay in the developmental stage of the plant itself. One-year-old 

 western white pine seedlings, whose buds are just opening and whose 

 tiny new needle fascicles are less than i/io inch long, show a particular 

 sensitiveness toward removal and replanting. 



FIEI/D TESTS 



The influence of the season of transplanting upon the behavior of the 

 tree in the plantation is of special interest to the forester. One hun- 

 dred of the plants from each of the nine spring lots described above 

 were planted October 6, 19 15, on the Wallace experimental area, near 

 Wallace, Idaho. A northwest aspect — a typical white pine planting 

 site — ^was selected. One row was devoted to each lot, and the rows were 

 placed adjacent to each other and parallel, extending up and down the 

 slope. The place where each tree was to be planted was previously 

 marked by a cedar stake 16 inches long, whose top had been dipped in 

 white paint to make it conspicuous among native cover plants. Each 

 stake bore its lot number in black lumber crayon. The same man 

 planted all the rows, using a uniform method. 



