4 MASS. EXPERIMENT STATION BULLETIN 421 



Inspection of Nursery Trees for Trueness-to-Name 



It is the prevailing practice to inspect nursery trees for trueness-to-name in 

 midsummer. Experience has shown that, in general, varietal differences are 

 most apparent in trees that are in active growth. When growth slows down as a 

 result of drought, lack of nutrients, insect or disease attacks, or cool fall weather, 

 some of the useful distinguishing characteristics often become less apparent or 

 disappear altogether. However, there is no one time when all of the plant char- 

 acters used in variet}' identification are most obvious or valuable. It is often a 

 good plan to study trees throughout the growing season in order to observe the 

 degrees of variation in the prominence of the various distinguishing character- 

 istics. 



Nursery trees have been examined successfully for trueness-to-name through- 

 out the period from June to October, which demonstrates that inspection can be 

 done almost anytime during the growing season. However, since early-season 

 inspection gives opportunity to detect mixtures before bud wood is taken for 

 propagation and since the small size of the trees at this time and the relative 

 freedom from insect, disease, and other damage facilitate rapid inspection, the 

 writers and their colleagues have in recent years examined fruit tree nursery 

 stock for trueness-to-name during the month of July so far as possible. 



It is true that nursery trees often vary in appearance when growing in widely 

 separated localities. Nevertheless, experience has shown that when a plant 

 character is altered b>- environment, the several varieties usually maintain their 

 relative order for that character. Hence, the identification of varieties in the 

 nursery row is feasible no matter where the>- are grown so long as the trees are 

 making good growth. Insect and disease damage on the one hand and spray 

 or dust deposits on the other may. sometimes increase the difficulty of positive 

 variety identification, but only rarely have these factors obscured all distinguish- 

 ing characteristics. 



How Pear Varieties Differ 



There are many plant characters of importance in distinguishing one pear 

 variety from another. Sometimes a single character is sufficient for positive 

 identification of a v-ariety; more often several characters are considered. Those 

 found by actual experience to be most useful are briefl>- described. The ac- 

 companying pictures (Figures 1-12) show specimens which illustrate some of 

 the more important distinguishing characters. It should be emphasized that, 

 since we are dealing with living plants, the character in question will not usually 

 be equally prominent in all individuals or in all portions of a single tree. Yet 

 these are characters by which varieties of pears may be distinguished. 



TREE CHARACTERS 



The habit, of growth usually refers to the position and length of individual 

 shoots on two-year trees. Usually, the term upright-spreading fairly well de- 

 scribes the growth habit of pear varieties. Occasionally, it may be spreading 

 as in Winter Nelis or even spreading to drooping as in Bantam. On the other 

 hand, it may be essentially upright as in Wilder. Some varieties are typically 

 crooked growers and often require staking to produce salable trees. Bosc and 

 Ewart are apt to be more crooked than most varieties (Figure 1). 



The vigor of a single variety varies widely in different soils, localities, and 

 seasons. However, after this fact has been taken into consideration, it is still 

 evident that comparative tree height is an important varietal characteristic. 



