DORMANCY IN BUDS 



245 



however, ethylene chlorhydrin proved most desirable; it is cheap, effective, 

 and has a relatively wide dosage margin between forcing action and tox- 

 icity. Fig. 94 shows ^ the effectiveness of ethylene chlorhydrin vapors in 

 forcing bloom in Azalea nudiflora. The plants are simply sealed in con- 

 tainers "with the required amount of ethylene chlorhydrin for 24 hours and 

 the chemical allowed to volatilize and enter the buds. From the figure it 

 is evident that 6.7 cc of 40 per cent ethylene chlorhydrin per 100 liters of 



FiGTJHE 95. Left: method of treating an individual dormant lilac bud with ethylene 

 chlorhydrin; a drop or two of the chemical is placed in the test tube and the tube sealed 

 over the bud with modelhng clay. Right: later growth of a bud treated in this way. 



space is adequate for forcing blooming and that 0.75 cc has some forcing 

 action. This treatment is effective in forcing both flower and foliage buds 

 of deciduous plants. Besides azalea, lilac, flowering almond, Bechtel's 

 crabapple, and Deutzia respond well to the treatment. Of those treated 

 only the snowball, Viburnum tomentosum, failed to respond. It is likely that 

 all deciduous forms can be forced by the proper concentration and time 

 of treatment or by the combination of a cold period followed by chemical 

 treatment. A more thorough study is needed of these and many other 

 forms in order to make the method highly useful to practical growers. 

 The chemical is toxic to leaves; consequently its use may be limited to 

 deciduous forms not in foliage. 



The seat of dormancy ^^ seems to be in the individual buds rather than 

 in the plant as a whole. Fig. 95 shows the method of treating an individual 

 dormant bud of lilac and the later gro'vvi^h of the treated bud. (Note that 

 the effect of the treatment is strictly local; the opposite bud on the same 

 stem one-fourth of an inch away remains dormant.) The roots and stems 

 of the plant are not dormant but are able to furnish the bud the necessary 

 water and other nutrients at any time that the bud is out of dormancy 

 and ready to grow. As we have already mentioned under Dormancy in 

 seeds, buds that are only partially after-ripened due to insufficient period 



