GENERAL POINTS CONCERNING FRUIT TREE STOCKS 177 



nine trees out of a hundred are on mahaleb stock as there is less 

 loss. Cherry on mazzard should cost twice as much, but is worth 

 the price. Mahaleb is sometimes better than mazzard in shallow 

 or wet soil. Possibly this is the most inportant influence of stock 

 on cion, for through it many fruits, which would not thrive, in 

 some cases would not live, on their own roots, can be grown in 

 unfavorable soils. The use of stocks to overcome soil adversities 

 demands much more attention than has been given. 



3. Through the stock, plants may be made to endure incompatible 

 climates. It would be too much to say that hardiness as an in- 

 herent quality is transmitted from stock to cion, but it is very cer- 

 tain that increase in vigor imparted by some stocks gives greater 

 hardiness to grafted plants. In the case of late-growing apples 

 worked on Hibernal or Oldenberg stocks greater hardiness results, 

 because the cion matures earlier than it would upon its own roots 



FIG. 149 HEELING- IN TREES FOR WINTER STORAGE 



and is therefore better able to withstand the winter. Again, slight 

 obstructions to the sap flow imposed more or less by union of dif- 

 ferent tissues of stock and cion may cause the cion to ripen 

 earlier and thus bring about greater hardiness. Some V' an ts, as 

 peach, must have a warm soil ; therefore, peach does better on plum 

 in cold soils than on its own roots. 



4. Stocks, if diseased, may impart the disease to cions, as when 

 peach stocks infested with peach yellows or "little peach" are budded 

 with healthy buds. 



5. Productiveness of tree is often increased by stock, paradoxically 

 enough, either by increasing or by decreasing plant vigor. Trees 

 sometimes fail to fruit well because of too much wood growth, in 

 which case grafting on less- vigorous stocks checks growth and 

 makes for productivity ; thus we may explain the greater fruit- 

 fulness of some dwarf apples and pears. On the other hand, a 

 fruit may be too weak in growth to be fruitful, hence 

 grafting on a stock which imparts vigor may make it more pro- 

 ductive. 



6. Time of maturity of both wood and crop may be changed 

 somewhat by stock hastened on the one hand or retarded on the 



