NURSERY PRACTICE FOR PRAIRIE-PLAIXS PLANTING 99 



Out of a number of possible methods, hardwood (dormant wood 

 cuttings and root cuttings are most commonly used for propagation 

 outdoors. Neither requires bottom heat, shading, or the great care 

 which is essential for softwood (summer wood) cuttings. 



Recent discoveries in propagation have demonstrated that material 

 benefit may be obtained from the use of so-called growth hormones, 

 which have the effect of promoting root development, thus assuring a 

 higher percentage of rooted plants and better stock. The most sal is- 

 factory rooting stimulants found to date are indoleacetic acid and 

 indolebutyric acid. They react differently on the various specie-, 

 but either if used in excess may cause damage to the cuttings. The 

 general method in practical use is to obtain rut tings in early spring and 



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Figure 34. — Tamarix propagated in the nursery from cuttings. 



to soak the lower end for 1 or 2 days in a solution consisting of 5 to 

 20 mg. of the growth hormone dissolved in 1 liter of water. For some 

 species, concentrations as high as 50 mg. to 1 liter have been used, but 

 it is generally safer to use a lower concentration and to extend the 

 time of treatment. 



Hardwood cuttings are best taken in the fall or winter, preferably 

 from 1- and sometimes 2-year wood; 8 to 10 inches is a satisfactory 

 length. Tied into bundles of convenient size, the tops are dipped for 

 about an inch or so in a solution of whitewash as a convenient means 

 of ready identification, and the bundles are then placed in moist sand 

 storage at a temperature of 35° to 50° until planted, or buried in out- 

 door pits below the frost line, preferably in well-drained sandy soils. 



Cuttings taken in the spring have not always proved satisfactory 

 since they have a tendency to leaf out in advance of root ing and conse- 

 quently to exhaust their vitality and succumb before the roots have 

 become established. No doubt, hormone treatment of such cuttings 

 will aid in obtaining a higher percent of successful rooting. It remains 

 to be determined experimentally whether such treatment is justified, 

 however, in view of the fact that cuttings of tamarix. willow, and 

 poplar, taken in fall or early winter and stored in damp sandy soil, 

 have rooted quite successfully in the spring. 



