4 MASS. EXPERIMENT STATION BULLETIN 418 



Near standard or standard stocks: Mailing X — Not named 



XII — Not named 

 " XIII — Black Doucin 

 " XV — Not named 



" XVI — Ketziner Ideal 



The classification into very dwarfing, semi-dwarfing, and standard rootstocks 

 is to be taken only in a general way. The stock effect varies with the variety. 

 A given stock may produce small trees of some varieties and larger trees of other 

 varieties. 



Certain other rootstocks have been used to a limited extent. Mailing A, C. F, 

 and H are unnamed seedling selections. They are, with the exception of H, all 

 vigorous growing stocks and do not always root well in the stock bed. Trees 

 budded on these stocks have shown no distinct dwarfing effect. Mailing H is a 

 very wayward growing, thorny stock that seems to show no valuable qualities. 



Two rootstocks sent out by the U. S. D. A. have been tried to a limited extent. 

 One known as Spy 227 is derived from a seedling of Northern Spy and is resis- 

 tant to the woolly aphis, a quality of little importance in northern orchards where 

 the woolly aphis does little damage. This rootstock does not seem to be adapted 

 to a wide range of varieties. It is reported to have considerable dwarfing effect. 

 Another stock known as Vt. 323 is a vigorous stock inclined to produce many 

 short thorny growths from the stem. It seems to be of value when large vigorous 

 orchard trees are desired, but should not be used for growing semi-dwarf trees. 

 None of these rootstocks seem likely to come into general use in this region. 



It is not proved that the Mailing rootstocks are truly clons; that is, that each 

 is derived from one seedling tree; therefore, they are called types rather than 

 clons. All trees of a given type are alike insofar as the writer has been able 

 determine. This being so, it is remarkable if more than one seedling is repre- 

 sented in a given type when it is pure and unmixed. Among the hundreds of 

 cultivated varieties originating from seedlings and propagated in nurseries, all 

 of which are true clons, it is doubtful if there are any that cannot be recognized 

 and distinguished from all others in the nursery row. The writer is convinced 

 that the Mailing types are true clons. 



Formerly, both seedling and clonal rootstocks were largely imported from 

 Europe by American nurserymen, but since 1928 importation has been forbidden 

 on account of the danger of importing plant pests. Previous to this quarantine 

 order, many seedling stocks were grown, mostly in Kansas and in the Pacific 

 northwest, and sold to nurserymen in all parts of the country. These stock 

 growers have continued to supply nurserymen with seedling rootstocks since 

 importations were forbidden, and some have attempted to produce clonal stocks 

 by various methods. At the present time, owing to the increased demand for 

 dwarf and semi-dwarf trees, there is increased interest in growing clonal root- 

 stocks. It is more difficult and a little more expensive to grow clonal rootstocks 

 than seedling rootstocks, but the present high price of dwarf trees is due to the 

 relation between supply and demand more than to the increased cost of growing 

 trees on the dwarfing rootstocks. 



The clonal rootstocks now being grown in this country have come in part 

 from the importations by the U.S.D.A. and experiment stations previously re- 

 ferred to and in j)art from prequarantine importations by nurserymen. The 

 writer has seen many stocks descended from these earlier importations. All have 

 been Mailing II, III, or V, or often a mixture of two or all three of these. We 

 had some stocks many years ago under the name of French Paradise which were 



