119 



cuttings and our best liybrids are likely to be the stubborn ones. 

 Often ten jxt cent of a collection of cuttings of a certain variety 

 will root and perhaps 90 per cent of another variety, but seldom 

 do 100 per cent of a large collection respond according to our 

 wishes. 



In a study of the effect of factors governing response of 

 holly (Ilex opaca) we found many variables. First of all not all 

 the cuttings of a collection from any one tree will form roots. 

 A 60 to 70 per cent response is common for the best trees. Sec- 

 ond, when we compare one tree with another there appears to 

 be a regular variation for each tree. Whether the variation is 

 due to inherent causes of whether the possibilities for selecting 

 uniform cuttings is greater in one case than in another is not 

 known. The fact is that they vary. 



The best time to propagate holly is from August to January 

 I in this section of the country. Collections coming in after 

 Januar}- i have often shown frost injury and have done poorly. 

 Current growth about 4 to 5 inches in length is better than other 

 age wood though good results may be had with two-year-old 

 wood attached where there is a short growth of current year stem. 

 Even four- or five-yearold stems may be used but the percentage 

 of rooting will be less with such material. 



Cuttings of evergreen holly must have a few leaves to assist in 

 root production. Stems of material taken in October, 1928, were 

 ver}- low in starch but on December 15, when the cuttings were 

 rooting an abundance of starch was found. At the same time 

 starch is increasing reducing sugars decrease so that the end of the 

 experiments the amount of sugar is much less than at the begin- 

 ning. 



Extra light from 1,000 watt nitrogen bulbs for 6 hours each 

 night while the cuttings were in the medium greatly increased 

 root growth and in some varieties increased the percentage of root- 

 ing. There was an indication that the longer the illumination 

 period, the better for cuttings. Care must be taken, however, to 

 prevent drying since the electric lights have a tendency to lower 

 the humidity of the air over the cuttings. 



Temperature best for rooting holly cuttings ranges from 65° to 

 75° F. Some rooting can be obtained at higher or lower tempera- 



