45 8 



Yearbook^ of Agriculture 1949 



not be reworked at the proper time to 

 keep the disease under control. A fur- 

 ther set-back resulted from accelerated 

 cutting of white pine that produced 

 about 11 billion board feet of lumber 

 for war use. The logging changed the 

 status of a large acreage from mature 

 stands to cut-over lands, much of 

 which now supports white pine repro- 

 duction and ribes. Viable ribes seed 

 stored in the forest-floor mantle during 

 the early formation of the mature 

 stands were released by the logging 

 disturbance and produced bushes 

 which must be removed to prevent loss 

 of the young pine crop. 



Thus at the end of the war came the 

 need for a large rework program and 

 for the removal of ribes from a large 

 unworked acreage. Because the annual 

 pine losses continue where ribes are 

 present, much of the work is urgent, 

 particularly in the younger stands. The 

 longer it is delayed, the greater the loss. 

 We think the most economical pro- 

 cedure is to establish the work on a 

 stable basis that would provide for all 

 the rework as it comes due each year 

 and for extending initial work to un- 

 protected stands as rapidly as possible. 



The blister rust fungus cannot be 

 eradicated but it can be controlled. 

 We must pay the cost of saving the 

 white pines. Past work and continu- 

 ance of the control program will as- 



sure white pine production on a large 

 part of the control area. In other parts, 

 the existing white pines will be lost to 

 the disease unless the areas are put in 

 condition to grow white pines by re- 

 moving the ribes. The selected acreage 

 can be enlarged by planting good sites 

 where ribes are absent or so few that 

 they can be easily eradicated. Increas- 

 ing application of forest-management 

 practices in the production of white 

 pine will help suppress ribes. The pros- 

 pect is good for finding a cheap chem- 

 ical for killing ribes that are resistant 

 to 2,4-D. Cooperating public and pri- 

 vate agencies and individuals are striv- 

 ing to control blister rust and there is 

 an active public interest in the prob- 

 lem. Thus, the outlook is favorable for 

 ultimately controlling the disease in se- 

 lected white pine forest areas. 



J. F. MARTIN is head of the Division 

 of Plant Disease Control,, Bureau of 

 Entomology and Plant Quarantine, 

 and directs the cooperative programs 

 for control of white pine blister rust 

 and stem rust of small grains. 



PERLEY SPAULDING is a pathologist 

 in the Division of Forest Pathology, 

 Bureau of Plant Industry, Soils, and 

 Agricultural Engineering. He per- 

 formed much of the early investiga- 

 tional work and research on the white 

 pine blister rust fungus. 



DWARF MISTLETOES 



LAKE S. GILL, JESS L. BEDWELL 



The dwarf mistletoes are serious 

 pests of western coniferous forests. The 

 losses they inflict in volume of timber 

 and quality of lumber have never been 

 accurately evaluated but are believed 

 to be exceeded only by the damage 

 done by heart rots. 



The dwarf mistletoes belong to the 

 genus Arceuthobium (it is also called 

 Razoumofskya) , a group of the family 

 Loranthaceae, of which all mistletoes 

 and some other parasitic plants are 



members. Among their next of kin, in 

 the genus Phoradendron, are the famil- 

 iar Christmas mistletoes, which attack 

 mostly deciduous trees and junipers. 

 In North America the junipers and 

 their relatives are immune to dwarf 

 mistletoes, although the generic name, 

 Arceuthobium, is derived from Greek 

 words meaning "juniper living," be- 

 cause juniper is the most common host 

 in the Mediterranean region, where 

 these plants were first described. They 



