82 MASS. EXPERIMENT STATION Rl'LLETlN 274 



trees tliat are inleriiiediate in appearance and it will be difficult to say which 

 variety they are. If, on the otiier hand, one can find no intermediate forms, 

 it is safe to say that a mixture has been found. Usually otiier trees like the 

 stray will appear on further examination. 



Atmospheric conditions are of some importance in examination of mixtures 

 in the nursery. The best condition is when the sun is lijrhtly clouded over 

 and casts no strong shadows. Under such conditions many varietal differ- 

 ences show u]i best. If the sim is shining it is well to face away from the sim 

 so that its liaht comes from the rear onto the trees and is reflected back to 

 the eye. 



The Age of the Tree 



Nursery trees are classed as one-year and two-year trees. Some so-called 

 two-year trees are really three years old, having been cut back severely at 

 two years old and nearly all the one-year growth removed. Such trees grow 

 a new top during the following summer and can be distinguished from true 

 two-year-old trees only by rather careful observation. So far as variety 

 identification goes they may be classed with two-year trees. 



Identification of one-year trees must depend solely on leaf and bark char- 

 acters and the size of the tree. In many cases a group of trees of an odd 

 variety are shorter or taller than the true variety or they are more slender 

 or more stocky. Uninjured leaves on these one-year whips are very character- 

 istic in size, serration, texture and pose. The color of the bark, the lenticels 

 and often the buds and general characteristics of node and internode are 

 distinct and characteristic of the variety. A stray tree or more especially a 

 group from a single bud stick can be seen from a considerable distance. It 

 is scarcely more difficult to identify varieties from one-year whips than from 

 older trees. 



In two-year trees there are present the additional characters of branch 

 angle and the entire growth habit of the variety not seen in one-year trees. 

 Also the shoulder or point of union of the branch and main axis often shows 

 characteristics peculiar to the variety. 



With increasing age of the tree after setting in the orchard, the tree takes 

 on the form of top characteristic of the variety, while the leaf and bark 

 characters of nursery trees still persist though to a less striking degree. Red 

 .\strachan develops a goblet shaped top, while Delicious develops an upright 

 straggling form. Wagener takes on a very narrow upright form. Jonathan 

 forms a round head, and Rhode Island Greening grows into a low, broad, 

 flat-topped tree. The form of the top may be modified in some degree by the 

 type of pruning followed, but only with very severe and persistent pruning 

 can the characteristic top of a variety be greatly modified. When the tree 

 begins to bear heavy crops, it spreads out and the form is naturally changed; 

 but with bearing, the emphasis changes to the fruit, and tree characters lose 

 their importance for identification purposes. 



Common Nursery Mixtures 



There are certain variety mixtures that occur more or less frecpiently and 

 so seem worthy of special mention. These come to light in orchards and so 



