16 



CIRCULAR 6 2 7, U. S. DEPARTMENT OF AGRICULTURE 



32° F., and such fruit lost its capacity to ripen while still firm and 

 apparently sound. At higher temperatures (50° to 80°) the peaches 

 soften as they ripen. Blake and Davidson (10) designated three 

 degrees of ripeness with the pressure-test range characteristic of each. 

 Peaches testing 14 to 12 pounds 0i 6 -inch plunger on unpared surface) 

 were designated hard ripe; those testing 11 to 8 pounds were firm ripe: 

 and those testing 6 pounds or less were soft ripe or in prime edible 

 condition. Haller and Harding (27) indicated the soft-ripe condition 

 is attained in peaches testing about 2 pounds (with the skin removed). 

 Although methods of testing firmness of peaches have varied con- 

 siderably, it is usually considered that pressure-test readings are of 

 value in establishing color standards for picking peaches. These 

 standards may vary somewhat, depending on variety, condition of 

 tree, distance to market, refrigeration, and method of testing. As 

 with pears, the pressure test has not been found of value in following 

 ripening of peaches in cold storage. 



Table 4. — Pressure-test limits recommended for indicating color standards for 



picking peach varieties 



[Plunger, 5 Ae of an inch in diameter: penetration, He of an inch] 



Variety 



Pressure-test 



limits 



(pounds) 



State 



Remarks 



Litera- 

 ture 

 refer- 





Upper 



Lower 



ence 



Belle 



14 



12 



20 



18 

 I 16 



20 



18 

 i 18 



17 



20 

 { 14. 5 



17 



!' S 



1 20 

 I 15.5 



14 

 14 



12.5 



9 

 14 

 14 

 12 

 12 

 12 

 15 

 15 

 17 

 11 

 15 

 12 

 15 

 17 



11.5 

 11 



8 



Virginia 



do 



Pared 



(27) 





do 



(27) 





California. 



do 



(42) 



Earlv Elberta 



Utah 



California 





(14) 





Pared... ... . 



(42) 



Elberta 



Utah 



do 



do 



New Jersey 



do 



Virginia 



New Jersey 



Utah 



New Jersey 



do 



Unpared; trees weakly vigorous 



Unpared; trees moderately vigorous. 



Unpared; trees highly vigorous 



L T npared; for nearby shipping 



Unpared; for long-distance shipping. 

 Pared 



(W 

 (14) 

 04) 





(10) 

 (10) 

 (27) 





Unpared; for nearby shipping 



(10) 





(14) 



J. H. Hale 



Unpared; for nearby shipping 



Unpared; for long-distance shipping. _ 

 Pared. . . ... .. 



(W) 





(10) 





Virginia 



California . 



(27) 



Triumph . ... 



do 



(42) 



Tuscan (Tuskena) . 



.... do 



do 



(42) 











Plums 



The color and firmness of plums have been used as indexes of ma- 

 turity. As with peaches, the firmness is a better measure of the carry- 

 ing quality and is used largely to determine the color standard for 

 picking. Pressure-test standards for maturity of plums have been 

 determined only in the Western States. These standards are sum- 

 marized in table 5 and are for use in long-distance shipment to market. 

 It will be noted that when the fruit can be promptly cooled and 

 shipped under relatively low temperatures it can be picked in a con- 

 siderably softer and more mature condition, with a consequent im- 

 provement in dessert quality. 



