152 



hybrid that brings together the greater 

 drought and frost resistance of the 

 knobcone pine and the rapid growth 

 and good form of Monterey pine. 

 Studies under way at the Institute of 

 Forest Genetics suggest that practical 

 methods of vegetative propagation 

 may be found to establish plantations 

 made up of superior clones of this 

 hybrid. 



California's infant paper industry 

 may in time derive much of its raw 

 material from plantations of this and 

 similar hybrids in the foothills sur- 

 rounding the great Central Valley, at 

 the lower border of the pine belt. Al- 

 though the area is known to favor ex- 

 cellent growth of ponderosa pine, it 

 has produced little pine timber in re- 

 cent years because of frequent fires and 

 rainfall conditions that are not often 

 favorable to the natural establishment 

 of ponderosa pine seedlings. 



Both Monterey and knobcone pines 

 carry their own fire insurance in the 

 form of cones that open after fires and 

 shower the burned-off areas with mil- 

 lions of seeds. The hybrid between 

 these species is highly fertile and has 

 "fire cones," which are produced abun- 

 dantly when the trees are little more 

 than 5 years old. 



Several hybrids between the so- 

 called yellow pines show great promise 

 for the semiarid West, although no cer- 

 tain cases of hybrid vigor have been 

 found. Ponderosa pine of the Pacific 

 slope is known to grow more rapidly 

 than the Rocky Mountain ponderosa 

 pine, but the ability of the coastal va- 

 riety to thrive in the Rocky Mountain 

 region or in the Southwest is open to 

 serious question. In tests in California, 

 however, the hybrids of these two have 

 caught up to ponderosa pine in height 

 growth at 5 years. A distinct possibility 

 is thereby offered to the forest planters 

 in the Rocky Mountain region and the 

 Southwest. An even more promising 

 hybrid has been made by crossing pon- 

 derosa pine with Apache pine, a close 

 relative from Arizona. The hybrid is 

 remarkable for its rapid root penetra- 

 tion and diameter growth, both of 



Yearbook^ of Agriculture 1949 



which greatly exceed those of ponder- 

 osa pine, and for the fact that it equals 

 ponderosa pine in height growth. 



Jeffrey pine, a native of California, 

 Oregon, Nevada, and Mexico, and 

 long thought to be closely related to 

 ponderosa pine, is generally of excel- 

 lent form but of slower growth than 

 ponderosa. A few years ago Jeffrey pine 

 was found to have crossed, in several 

 parts of its range, with Coulter pine, 

 a species found only in California and 

 Mexico. 



Coulter pine, under California con- 

 ditions, is one of the fastest growing 

 pines although it is limby and relatively 

 short-lived. Pollen from the natural 

 hybrid between these pines, applied to 

 flowers of Jeffrey pine, produced an 

 abundant crop of backcross hybrids. 

 In repeated tests these hybrids have 

 grown almost as fast as Coulter pine, 

 and have exhibited as good crown and 

 stem form as Jeffrey or ponderosa pine. 

 Elsewhere in this Yearbook, an account 

 is given of insect resistance of this in- 

 teresting hybrid, which may yet offer 

 stiff competition to pondersa pine, 

 heretofore the undisputed king of the 

 western pines. 



THESE RESULTS of research are en- 

 couraging. The principles and tech- 

 niques of pine breeding are reasonably 

 well worked out. Hybrids and strains of 

 superior growth rate, hardiness, insect 

 resistance, gum yield, and other quali- 

 ties have been produced with trees 

 from widely separated localities. The 

 superior forms so far produced should 

 be very useful, but they cannot be ex- 

 pected to grow equally well under all 

 climatic and soil conditions. As with 

 other crops, it will be necessary to breed 

 pines to fit the major climatic regions 

 and in some cases particular sites with- 

 in a region. 



The present status of pine breeding 

 might be likened to that of corn breed- 

 ing in the early 1930's. The principles 

 and techniques had been pretty well 

 worked out by various research work- 

 ers, and a number of high-yielding corn 

 strains had been produced. The next 



