14 BULLETIN 974, U. S. DEPAETMEISTT OF AGRICULTUKE. 



(8) Watering should be as infrequent as practicable, only sufficient to keep 

 the cutting bed moist but well aerated and the atmosphere in the box saturated. 

 If the glass fits tightly, the period between necessary waterings may extend over 

 several weeks.. 



(9) Place the box for a month in a temperature of 55° to 60° or 65° F., Ib 

 either darkness or indirect sunlight. At the end of a month the new healing- 

 over growth, called a callus, should have formed at the base of each cutting. 



(10) After the cuttings are callused the temperature in the cutting house 

 should be allowed to run down each night to a temperature of 35° F. or as near 

 that point as the weather permits, but the cuttings should not be allowed to 

 freeze. The day temperature should approach but not exceed 60°. Shade the 

 boxes from direct sunlight, but give them all the indirect light practicable. 



(11) After two months of this alternate chilling and moderate warming the 

 buds on many of the cuttings should have begun to push. It is then time to 

 raise the night temperature to 55°, keeping the day temperature at about 60° F. 



(12) After new twigs have developed from the upper buds (PI. XIII) 

 and their groT\i;h has been terminated by the browning and shedding of the 

 tips, and the new leaves have reached their full size and acquired the dark- 

 green color of maturity, the formation of roots is about to begin. (PI. XIV, 

 fig. 1, and PL XVL) 



(13) When all or most of the cuttings in the frame have begun to root, ven- 

 tilation of the box should be begun. The best superficial evidence that a cut- 

 ting has rooted is the development of secondary twig growth, either from the 

 apex of one of the first set of new twigs or from another bud lower down on 

 the old wood of the cutting. (PL XIV, fig. 2, and PL XV.) If secondary 

 growth does not take place, the development of a plump but dormant bud at the 

 apex of one of the leafy twigs is also good evidence that the cutting has begun 

 to root. Cuttings that are healthy but not yet rooted at the time ventilation 

 begins usually die from excessive transpiration. 



(14) Ventilation should be only slight at first and should be increased very 

 gradually, the transition to full ventilation extending over a period of several 

 weeks. If any of the sensitive secondary growth begins to wilt, reduce the ven- 

 tilation immediately until the wilting ceases. Be especially careful not to give 

 too much ventilation on windy days. By the time the tips of the secondary 

 shoots are browned and shed and their leaves are mature in size and color, the 

 cuttings have developed sufficient root growth to warrant full ventilation. 



(15) All cuttings that are dying should be removed from the bed at once. 

 Those injured by high temperature usually turn brown at the base first, the 

 dead area extending upward until the new growth collapses. Those otherwise 

 sound but suffering from excessive ventilation before they are rooted usually 

 indicate their bad condition by the marginal yellowing of their leaves before 

 they drop and the stems become withered. 



(16) The plants are best left in the cutting bed all winter, either indoors at 

 a temperature slightly above freezing, or outdoors mulched with leaves, pref- 

 erably oak leaves. In early spring, before the buds have begun to push, they 

 should be very carefully lifted and moved, with the whole root mat and ad- 

 hering soil intact (PL XVI), to a peat and sand nursery bed at a spacing of 

 about a foot each way or potted in the standard blueberry-soil mixture. 



KOOT CUTTINGS. 



The early experiments with root cuttings gave such a small per- 

 centage of rooted plants that further experiments in the greenhouse 

 were abandoned. At Whitesbog, N. J., however, in order that the 



